# Anvilfield - HVAC field guides

External static pressure, CFM, duct leakage, charging, balancing, and commissioning notes.

Hub: https://anvilfield.com/field-guides/hvac/

Field guides (126):
- https://anvilfield.com/field-guides/hvac/retro-commissioning-existing-buildings/ - Retro-commissioning is the process of commissioning an existing building that was never commissioned or has drifted out of tune, getting the equipment already installed to work as intended. It is the highest-return energy measure because most fixes are no-cost and low-cost operational corrections, not new equipment. ASHRAE guidelines and a commissioning authority frame the work.
- https://anvilfield.com/field-guides/hvac/predictive-maintenance-condition-monitoring/ - Predictive maintenance (PdM) watches a machine's own condition, its vibration, heat, and oil, to catch a failure developing and fix it just before it fails. It sits above reactive run-to-failure and scheduled preventive maintenance because you act on evidence, not a guess. Rank assets by criticality, trend against a baseline, and act in the P-F window.
- https://anvilfield.com/field-guides/hvac/indoor-air-quality-monitoring-sensors/ - Indoor air quality monitoring is the continuous, real-time measurement of the air people breathe indoors, the sensors plus the dashboard plus the alerts. Unlike a one-time investigation that diagnoses a complaint, monitoring watches the air all the time. The value is the response. A reading nobody acts on is just a number on a screen.
- https://anvilfield.com/field-guides/hvac/construction-warranty-management-closeout/ - Construction closeout is the final phase that transfers a finished, operable building to the owner along with the records: the as-builts, the O&M manuals, and the warranties. The work being done is not the job being done. Start collecting closeout documents on day one, and let the contract, the warranty terms, and the AHJ control.
- https://anvilfield.com/field-guides/hvac/warranty-reserve-cost-management/ - Warranty cost management is pricing, reserving for, and reducing the callbacks and rework that land after a job closes. Every job carries a warranty obligation, and honoring it costs real money after you already booked the profit. Set aside a reserve from your own history and kill the root causes. This is general education, not accounting or legal advice.
- https://anvilfield.com/field-guides/hvac/value-engineering-construction/ - Value engineering is a structured method to improve a project's value, where value is the function a system delivers divided by its life-cycle cost. The team analyzes what each element must do, then finds another way to deliver that function for less without losing performance. It is not line-item cost-cutting, and the owner decides.
- https://anvilfield.com/field-guides/hvac/service-truck-inventory-van-stock/ - Service truck inventory is the stock of parts each service vehicle carries so the technician fixes the job on the first trip without a supply-house run. It decides first-time fix and margin. Stock from usage data, set min and max par levels per truck, and bill every part off the work order.
- https://anvilfield.com/field-guides/hvac/service-dispatch-technician-scheduling/ - Service dispatch is assigning and sequencing jobs across your technicians, deciding who goes where and when, so the right tech arrives with the right parts and information. Good dispatch raises billable hours and first-time fix rate. Bad dispatch wastes non-billable windshield time and sends the wrong skill. Match skill to job, cluster work by area, and reserve capacity for emergencies.
- https://anvilfield.com/field-guides/hvac/service-agreements-recurring-revenue/ - A service agreement is a recurring contract where a customer pays a set fee for scheduled maintenance and priority service, turning one-time jobs into predictable revenue. It smooths the slow season, retains customers, and pulls through repair and replacement work. Price each tier for profit, schedule and deliver the visits, and your business is worth more at sale.
- https://anvilfield.com/field-guides/hvac/respiratory-protection-program-osha/ - A respiratory protection program is the full set of OSHA 1910.134 requirements an employer runs when workers wear respirators: hazard assessment, respirator selection, medical evaluation, fit testing, training, and maintenance. A mask off the shelf is not compliance. OSHA cites the missing program, not just the missing respirator, and engineering controls come first.
- https://anvilfield.com/field-guides/hvac/refrigerant-oil-return-long-line-sets/ - Oil return is keeping the compressor's lubricating oil moving with the refrigerant and back home, because the oil leaves with the discharge gas and a system that does not bring it back runs the compressor dry until it fails. On long runs and tall risers, velocity carries the oil. The equipment manufacturer sets the limits.
- https://anvilfield.com/field-guides/hvac/overhead-recovery-bid-markup-strategy/ - Overhead recovery is charging every bid its share of the cost of running the company, then a profit on top, through the markup. The trap is markup versus margin: markup is on cost, margin is on price, so a 20 percent markup is only a 16.7 percent margin. Price from your own numbers.
- https://anvilfield.com/field-guides/hvac/natatorium-indoor-pool-dehumidification/ - A natatorium is an indoor pool room, and its HVAC has to remove the moisture that warm pool water evaporates, hold the space humidity below the point where the building sweats, keep the room under negative pressure so chloramine-laden air stays in, and exhaust those fumes at the deck. ASHRAE, the dehumidifier manufacturer, and the design control the targets.
- https://anvilfield.com/field-guides/hvac/mold-remediation-iaq-iicrc-s520/ - Mold remediation is the controlled removal of mold growth and the correction of the moisture source that fed it. Clean the mold without fixing the water and it returns. Done to IICRC S520 and EPA guidance, the work means containing the area under negative pressure, removing porous materials, HEPA-cleaning the rest, and verifying with a third-party professional.
- https://anvilfield.com/field-guides/hvac/laboratory-fume-hood-exhaust-ventilation/ - A laboratory fume hood is the primary device that protects a worker from toxic, flammable, or corrosive fumes, pulling air in across the sash opening and exhausting it outside. The hood, dedicated exhaust, fan and stack, and negative-pressure room form a life-safety system, but ANSI/AIHA Z9.5, the project engineer, and the AHJ control the design.
- https://anvilfield.com/field-guides/hvac/jobsite-logistics-site-planning/ - A site logistics plan is the layout and rules for moving people, material, and equipment on and around a jobsite: laydown and staging, access and haul routes, crane and hoist placement, temporary facilities, deliveries, and phasing. On a tight site it matters as much as the schedule, and it changes as the building grows.
- https://anvilfield.com/field-guides/hvac/indoor-air-quality-investigation-testing/ - An indoor air quality investigation is a structured hunt for the cause of an air complaint, starting with the people, the complaint pattern, and the building history, then a walkthrough, with the meter last. Check carbon monoxide first for safety. Most causes trace to ventilation or moisture, not the air itself, and health calls go to an industrial hygienist.
- https://anvilfield.com/field-guides/hvac/hydronic-balancing-valves-circuit-setter/ - A hydronic balancing valve sets and verifies the water flow (gpm) to each coil, terminal, and branch so close loads do not hog the flow and far loads do not starve. A manual circuit setter is set by hand and read at its ports; a PICV holds flow regardless of pressure. Balance to design flow.
- https://anvilfield.com/field-guides/hvac/hvac-service-maintenance-agreement/ - An HVAC service maintenance agreement is a recurring contract where the customer pays a set fee for scheduled maintenance in exchange for priority service and repair discounts. It turns one-off repair calls into predictable recurring revenue and pulls through bigger repair and replacement work. Price it from the true cost of the visits, and put the scope in writing.
- https://anvilfield.com/field-guides/hvac/hiring-onboarding-field-technicians/ - Hiring and onboarding field technicians is the work of finding, screening, paying, and keeping skilled techs, and in a labor shortage it sets the ceiling on how much work a shop can take. Recruit constantly, hire attitude and train skill, run a structured first 90 days, and pay a path people stay for; classification rules follow the law.
- https://anvilfield.com/field-guides/hvac/healthcare-hospital-hvac-ventilation-ashrae-170/ - Healthcare HVAC is the ventilation that performs infection control in a hospital, not comfort alone. It holds operating rooms positive so clean air flows out, isolation rooms negative so pathogens stay in, and delivers the air changes, filtration, and humidity each space needs. ASHRAE Standard 170 and the FGI Guidelines set these as requirements.
- https://anvilfield.com/field-guides/hvac/fire-smoke-damage-odor-restoration/ - Fire and smoke damage restoration stabilizes and cleans a building after a fire, matching the cleaning method to the smoke residue type and surface, removing odor at its source, and drying the suppression water. The acidic residue corrodes within hours, so the work runs against a clock. IICRC S700 practice, the product manufacturer, and the AHJ govern the scope.
- https://anvilfield.com/field-guides/hvac/fire-extinguisher-use-classes-pass/ - Fire extinguisher readiness means matching the extinguisher class to the fuel, using PASS (pull, aim at the base, squeeze, sweep), and fighting only a small fire with an exit behind you. Water on grease or energized electrical makes it worse. Inspect monthly, recharge after any use, and let OSHA, NFPA 10, and the AHJ govern.
- https://anvilfield.com/field-guides/hvac/customer-financing-options/ - Customer financing lets a homeowner pay for an HVAC replacement as a monthly payment, not a lump sum, while a third-party lender funds it and pays you up front. It removes the price wall and raises the average ticket, but it costs a dealer fee and carries compliance, so price the fee in and let the lender handle the loan.
- https://anvilfield.com/field-guides/hvac/contractor-succession-exit-planning/ - Succession and exit planning is the multi-year work of building a contracting business that runs without you and choosing how you leave it, whether family transfer, a management or employee buyout, or a sale. Every owner exits. The value you get depends on years of preparation, not the day you decide. This is education, not legal, financial, or tax advice.
- https://anvilfield.com/field-guides/hvac/commercial-refrigeration-walk-in-systems/ - Commercial refrigeration keeps food and product cold in walk-in coolers and freezers, reach-ins, and supermarket racks. It runs the same vapor-compression cycle as air conditioning, but at lower temperatures, with defrost, under near-continuous duty, and against food-safety rules. The manufacturer data, EPA refrigerant rules, and the food code control the limits.
- https://anvilfield.com/field-guides/hvac/commercial-kitchen-equipment-installation/ - Commercial kitchen equipment installation is mostly coordination: getting gas, electric, water, drain, and ventilation to land where each appliance goes, then hooking them up to code. The cookline restrains its gas, drains run to a floor sink through an air gap, and the hood and makeup air stay balanced. NSF listing and the health department control.
- https://anvilfield.com/field-guides/hvac/commercial-ice-machine-installation-service/ - A commercial ice machine is a refrigeration system that freezes water into cube, nugget, or flake ice for food service and healthcare. It runs the same cycle as any cooler, but the water side, the filtration that fights scale, the air-gapped drain, and the cleaning that fights mold decide whether it lasts. The manufacturer, NSF, and local code control.
- https://anvilfield.com/field-guides/hvac/combustion-analysis-flue-gas-tuning/ - Combustion analysis puts a calibrated analyzer probe in the flue to measure oxygen, carbon monoxide, flue temperature, and draft, then reads excess air and efficiency to confirm a gas appliance burns clean, safe, and efficient. Carbon monoxide is a life-safety hazard, so the manufacturer's targets, the fuel-gas code, and the AHJ govern every limit.
- https://anvilfield.com/field-guides/hvac/cold-storage-refrigerated-warehouse-design/ - A refrigerated warehouse is a building-sized cold box for cooler or freezer product. Scaling up from a walk-in adds two failures a small box never has: the freezer floor freezes the ground and heaves the slab unless sub-floor heat keeps it warm, and the inward vapor drive ices the panels at any breach. IIAR, ASHRAE, and OSHA control the limits.
- https://anvilfield.com/field-guides/hvac/cleanroom-hvac-contamination-control/ - A cleanroom HVAC system holds the air clean enough to make semiconductors, drugs, and medical devices by pushing HEPA- or ULPA-filtered air through the space at a high air-change rate, holding a pressure cascade from clean to dirty, and controlling temperature and humidity. It is certified to an ISO 14644 class by particle count, not by looking clean.
- https://anvilfield.com/field-guides/hvac/chiller-plant-sequencing-optimization/ - Chiller plant sequencing is the control logic that decides how many chillers run, which ones, and at what setpoints. Most of a plant's energy is won or lost here, not in the hardware. Staging too many machines at part load or holding setpoints at the design minimum can double kW per ton. Equipment limits and the project sequence govern it.
- https://anvilfield.com/field-guides/hvac/change-order-management-scope-control/ - A change order is the written, priced, and approved record of any change to the agreed scope, price, or schedule of a job. The customer asks for extras, the field finds hidden conditions, the design shifts. Get the change signed before you do the work, or you eat it. Verbal handshakes never get paid.
- https://anvilfield.com/field-guides/hvac/centrifugal-chiller-surge-control/ - Centrifugal chiller surge is a flow reversal in the compressor. A centrifugal machine develops head, not displacement, so when the lift it must make exceeds what it can produce at that flow, refrigerant reverses and slams back with a bang. High lift causes surge. Clean tubes, purge non-condensables, and never run a chiller through repeated surge.
- https://anvilfield.com/field-guides/hvac/building-automation-fault-detection-diagnostics/ - Fault detection and diagnostics, FDD, is software that reads a building automation system's trend data automatically to find faults, energy waste, and comfort problems, then diagnoses the likely cause and ranks them by cost and comfort. The value is the detect, diagnose, dispatch, verify workflow, not the dashboard. The platform and the facility control the scope.
- https://anvilfield.com/field-guides/hvac/bid-proposal-closing-sale/ - A winning HVAC proposal turns the estimate into a clear document the customer can say yes to: three good-better-best options, the value behind the price, the scope in writing, and a monthly payment. The cheapest bid does not always win. The clearest, most-trusted one does, and most contractors lose jobs by quoting and never following up.
- https://anvilfield.com/field-guides/hvac/apprenticeship-training-program/ - An apprenticeship and training program is the structured path that turns a green helper into a licensed journeyman: paid on-the-job hours, related classroom instruction, and competency milestones a mentor signs off. You cannot hire your way out of the skilled-trade shortage, so the shops that build techs win. Hours and licensing follow the DOL, your state, and the licensing board.
- https://anvilfield.com/field-guides/hvac/air-side-economizer-fault-detection/ - Economizer FDD is the logic that compares an economizer's expected state to its actual state and flags the fault when they disagree. A broken economizer runs mechanical cooling instead of free outside air and rarely throws a comfort complaint, so the waste goes unseen. Adopted energy codes now require FDD on many units; the equipment and the code edition control.
- https://anvilfield.com/field-guides/hvac/waterside-economizer-free-cooling/ - A waterside economizer, or free cooling, makes the plant's chilled water with the cooling tower alone when the outdoor wet-bulb is low enough, so the chiller compressor runs unloaded or shuts off. A plate heat exchanger between the tower water and the chilled-water loop is the common arrangement. The climate, the wet-bulb, and the design control the hours.
- https://anvilfield.com/field-guides/hvac/vav-cav-air-distribution-systems/ - A VAV (variable air volume) system holds the supply air at a constant cold temperature and varies the airflow to each zone through VAV boxes, while a CAV (constant air volume) system holds the airflow steady and varies the supply temperature. VAV saves fan energy and zones better; the project design controls the choice.
- https://anvilfield.com/field-guides/hvac/thermostat-types-installation-smart-controls/ - A thermostat senses room temperature and switches the HVAC equipment on and off to hold a setpoint. The thermostat has to match the equipment it controls: the number of heating and cooling stages, whether it is a heat pump, and low-voltage 24 V versus line-voltage. A mismatched thermostat is the common install error.
- https://anvilfield.com/field-guides/hvac/steam-pressure-reducing-valve-station/ - A steam pressure reducing valve station drops high-pressure distribution steam to the lower pressure a building or process needs. It is the reducing valve plus isolation valves, strainer, separator and drip trap, downstream safety relief, upstream and downstream gauges, and a bypass. The valve senses downstream pressure and modulates to hold the setpoint, with the manufacturer and ASME governing.
- https://anvilfield.com/field-guides/hvac/steam-heating-system-fundamentals/ - Steam heating makes steam in a boiler, lets it flow out on its own pressure to radiators and coils where it condenses and releases its large latent heat, then returns the condensate to the boiler to boil again. No pump moves the steam. Distribution rides the steam's own pressure, and the condensate comes back by gravity or a feed pump.
- https://anvilfield.com/field-guides/hvac/snow-melt-system-hydronic-electric/ - A snow-melt system embeds heating elements, either hydronic PEX tubing or electric resistance cable, in a driveway, walk, ramp, or stair to melt snow and ice automatically. Hydronic uses a boiler, a glycol loop, and a heat exchanger for large areas at lower operating cost; electric suits small areas. An automatic snow sensor runs it only when snowing and cold.
- https://anvilfield.com/field-guides/hvac/refrigeration-cycle-fundamentals/ - The refrigeration cycle moves heat from where you do not want it to where you do not care, using a refrigerant that changes state. Four parts run it: the compressor, condenser, metering device, and evaporator. The refrigerant boils in the evaporator to absorb heat and condenses in the condenser to reject it.
- https://anvilfield.com/field-guides/hvac/refrigeration-accessories-filter-drier-sight-glass/ - Refrigeration line accessories are the components plumbed into the refrigerant lines that protect the compressor and metering device: the liquid-line filter-drier removes moisture, acid, and debris, the sight glass shows the liquid charge and moisture level, and parts like the accumulator and receiver manage liquid. The filter-drier matters most. The manufacturer governs selection.
- https://anvilfield.com/field-guides/hvac/refrigerant-types-a2l-transition/ - An A2L refrigerant is a low-toxicity, mildly flammable refrigerant under ASHRAE Standard 34, the class now replacing high-GWP R-410A in new residential and light-commercial equipment. R-454B and R-32 lead the swap, driven by the EPA AIM Act HFC phasedown. A2L is hard to ignite but not nonflammable.
- https://anvilfield.com/field-guides/hvac/refrigerant-metering-devices-txv-orifice/ - A refrigerant metering device is the restriction between the high-pressure liquid line and the low-pressure evaporator that drops the pressure and meters liquid into the coil at the rate the load needs. A fixed orifice meters a set amount; a TXV or EEV modulates flow to hold evaporator superheat. The data plate and manufacturer set the match.
- https://anvilfield.com/field-guides/hvac/refrigerant-line-brazing-nitrogen-purge/ - Brazing a refrigerant line joins copper tubing with a high-temperature filler while dry nitrogen flows through the pipe to keep the heat from forming copper-oxide scale inside. That scale breaks loose and plugs the metering device and damages the compressor. Recover the refrigerant first, then pressure test the joints before you pull the vacuum.
- https://anvilfield.com/field-guides/hvac/refrigerant-evacuation-vacuum-dehydration/ - Evacuation is pulling a deep vacuum on a refrigeration or air conditioning system with a vacuum pump to remove air, moisture, and other non-condensables before charging. It is measured in microns on an electronic micron gauge, with a common target of 500 microns or below, proven by a standing decay test. The equipment manufacturer sets the number.
- https://anvilfield.com/field-guides/hvac/radiant-floor-hydronic-heating-design/ - Hydronic radiant floor heating warms a building by circulating warm water through PEX tubing set in or under the floor, so the floor surface itself radiates low-temperature heat upward. Supply water typically runs about 90 to 120°F, well below baseboard temperatures, but the floor covering, the design load, and manufacturer data set the actual number.
- https://anvilfield.com/field-guides/hvac/pump-cavitation-npsh-diagnosis/ - Pump cavitation is the collapse of vapor bubbles inside a pump, which happens when the suction pressure falls below the water's vapor pressure and the water flashes to vapor at the impeller. It sounds like gravel, erodes the impeller, and means NPSH available has dropped below NPSH required. Fix the suction side, not the pump.
- https://anvilfield.com/field-guides/hvac/ptac-pthp-package-terminal-units/ - A PTAC (packaged terminal air conditioner) is a self-contained heating and cooling unit that slides into a through-the-wall sleeve. A PTAC heats with an electric resistance strip; a PTHP heats with a heat pump and falls back to electric strip in the cold. Both fit a standard 42 by 16 inch sleeve that must pitch to drain.
- https://anvilfield.com/field-guides/hvac/psychrometric-chart-reading-field-guide/ - A psychrometric chart plots the properties of moist air. Measure any two, usually dry-bulb and wet-bulb, find where they cross, and read relative humidity, dew point, humidity ratio, enthalpy, and specific volume. The line between two points shows the heat and moisture change.
- https://anvilfield.com/field-guides/hvac/kitchen-exhaust-grease-duct-nfpa96/ - A commercial kitchen exhaust system is the hood, welded grease duct, and rooftop fan that pull grease-laden cooking vapor out of the building. The grease that collects inside is a major fire hazard, so NFPA 96 governs the construction, clearances, and periodic cleaning to bare metal. The adopted code edition and the AHJ control the specifics.
- https://anvilfield.com/field-guides/hvac/hydronic-expansion-tank-air-separator/ - A hydronic expansion tank absorbs the water that expands when a closed heating or cooling loop heats up, holding system pressure steady so the relief valve does not lift. A paired air separator strips the entrained air that would otherwise block flow and corrode the loop. The tank pre-charge and sizing follow the manufacturer's data.
- https://anvilfield.com/field-guides/hvac/hvac-zoning-systems-dampers-thermostats/ - HVAC zoning splits one heating and cooling system into separately controlled areas, each with its own thermostat and a motorized damper in the duct. A zone control panel reads the thermostat calls, opens dampers to the zones that need conditioning, and runs the equipment. ACCA Manual Zr and the equipment data govern the design.
- https://anvilfield.com/field-guides/hvac/hvac-vibration-isolation-equipment-mounting/ - Vibration isolation separates rotating or reciprocating HVAC equipment from the building structure with resilient mounts, so the equipment's vibration and structure-borne noise do not transmit into occupied spaces. It works when the isolator's natural frequency sits well below the equipment's operating frequency. The manufacturer's selection and the project design govern the deflection.
- https://anvilfield.com/field-guides/hvac/hvac-ventilation-rate-outdoor-air-ashrae-62/ - The ventilation rate is the amount of outdoor air a building brings in to dilute indoor contaminants, set as a minimum by ASHRAE Standard 62.1 for commercial spaces. Too little air means poor indoor air quality and a code violation. Too much wastes conditioning energy. The adopted code edition controls the actual minimum.
- https://anvilfield.com/field-guides/hvac/hvac-unit-heater-gas-electric/ - A unit heater is a self-contained heater, a gas burner or electric element plus a fan in one hung cabinet, that blows warm air straight into the space it heats with no ductwork. It heats garages, warehouses, shops, and loading docks. Gas units need combustion air, venting, and a CO check; the manufacturer data and the gas code control.
- https://anvilfield.com/field-guides/hvac/hvac-test-instruments-gauges-meters/ - HVAC test instruments are the meters and gauges a technician uses to measure a system instead of guessing: a manifold gauge set and thermometers for refrigerant charge, a micron gauge for vacuum, an anemometer and manometer for airflow and pressure, a combustion analyzer for gas safety, and a multimeter for electrical. Accuracy depends on calibration.
- https://anvilfield.com/field-guides/hvac/hvac-temperature-split-delta-t-diagnostics/ - The air-side temperature split (delta-T) is the return-air temperature minus the supply-air temperature across the cooling coil. A rough screening range is 16 to 22°F dry bulb, but the split shifts with indoor humidity, so read it against the return wet bulb. The split screens airflow and capacity. It does not set the charge.
- https://anvilfield.com/field-guides/hvac/hvac-system-types-overview/ - HVAC systems are sorted by how they make heating and cooling, how they distribute it (air, water, or refrigerant), whether the equipment is packaged or split, and whether it is one central plant or distributed per zone. The families include residential split systems, rooftop units, VRF, chilled-water plants, and boilers. The building load and design control the choice.
- https://anvilfield.com/field-guides/hvac/hvac-preventive-maintenance-program/ - HVAC preventive maintenance (PM) is scheduled inspection, cleaning, and service performed on a calendar interval to keep equipment efficient and reliable before it breaks, not after. Reactive breakdown repair typically costs three to five times more. The manufacturer's instructions and ANSI/ASHRAE/ACCA Standard 180 set the minimum tasks and intervals.
- https://anvilfield.com/field-guides/hvac/hvac-infrared-radiant-tube-heater/ - An infrared radiant tube heater warms people, the floor, and equipment directly with infrared energy, like the sun, instead of heating the air. That makes it efficient in high-bay, drafty, and open or outdoor spaces. A gas burner fires a steel tube and a reflector aims the heat down. Clearance to combustibles and venting control the install.
- https://anvilfield.com/field-guides/hvac/hvac-fan-array-fanwall-systems/ - A fan array, also called a fan wall, is a grid of small direct-drive plenum fans inside an air handler that does the work one large belt-driven fan used to do. The array gives N+1 redundancy, better part-load efficiency, a shorter cabinet, and more even airflow. The manufacturer's selection and the project design govern the capacity.
- https://anvilfield.com/field-guides/hvac/hvac-estimating-bidding/ - An HVAC estimate prices a job by adding five buckets: the equipment takeoff, the sheet-metal ductwork, the piping, the install labor in labor units, and overhead and profit. HVAC is equipment-heavy and labor-heavy at once. The project documents, the supplier quotes, and your own job-cost history control the number, not a rule of thumb.
- https://anvilfield.com/field-guides/hvac/hvac-duct-insulation-wrap-liner/ - Duct insulation slows heat gain and loss through the duct wall, stops a cold supply duct from sweating, and, applied as internal liner, cuts fan and airflow noise. Two methods do it: external wrap, a fiberglass blanket with a sealed FSK vapor jacket on the warm outside, or internal acoustic liner bonded inside. Code sets the R-value by location.
- https://anvilfield.com/field-guides/hvac/hvac-duct-cleaning-nadca-iaq/ - Air duct cleaning is the physical removal of accumulated dust, debris, and contamination from the whole HVAC system, supply, return, coil, blower, and plenum, to restore cleanliness and airflow. The EPA does not recommend routine cleaning. Clean when there is visible mold, verified vermin, or debris discharging from the registers, using NADCA source removal.
- https://anvilfield.com/field-guides/hvac/hvac-desiccant-dehumidification-systems/ - Desiccant dehumidification removes moisture by adsorbing water vapor onto a desiccant material, not by cooling air below its dew point on a coil. That reaches very low dew points a refrigerant coil cannot economically hit, but the process air leaves dry and warm, so most systems add post-cooling, and the manufacturer sets the target.
- https://anvilfield.com/field-guides/hvac/hvac-coil-types-cleaning-maintenance/ - An HVAC coil is a finned-tube heat exchanger that moves heat between the air and a refrigerant or water flowing inside the tubes. The main types are DX evaporator, condenser, chilled-water, hot-water, steam, and preheat coils. A dirty or damaged coil loses capacity and runs up energy use, so the manufacturer's cleaning and service instructions govern.
- https://anvilfield.com/field-guides/hvac/hvac-bas-ddc-controls-fundamentals/ - A building automation system, or BAS, is the network of digital controllers, sensors, and actuators that runs a building's HVAC automatically to a written sequence of operations, with a front-end for monitoring, trending, and alarms. Direct digital control, DDC, is the digital controllers inside it. The sequence and the point-to-point checkout decide whether it works.
- https://anvilfield.com/field-guides/hvac/hvac-air-distribution-diffusers-grilles-registers/ - Diffusers, grilles, and registers are the terminal devices that deliver supply air into a room and pull return air back. A grille is a faced opening with no damper, a register is a grille with a damper, and a diffuser spreads and mixes supply air, usually at the ceiling. Manufacturer performance data governs throw and noise.
- https://anvilfield.com/field-guides/hvac/heat-pump-reversing-valve-defrost/ - A heat pump reversing valve is a four-way valve that flips the direction of refrigerant flow, swapping which coil is the condenser and which is the evaporator. It lets one system both heat and cool, and it runs the defrost cycle by switching to cooling to melt frost off the outdoor coil. A small pilot solenoid shifts the main slide.
- https://anvilfield.com/field-guides/hvac/heat-pump-fundamentals-cop-defrost/ - A heat pump is an air conditioner that runs both directions: it moves heat instead of making it, so one refrigerant system heats and cools. In heating it pulls heat from outdoor air, even cold air, and pumps it inside. A reversing valve flips the cycle. Because it moves heat, output beats the electricity it draws.
- https://anvilfield.com/field-guides/hvac/gas-furnace-operation-troubleshooting/ - A gas furnace burns natural gas or propane to heat air, and a blower pushes that warm air through the duct system. A thermostat call starts a timed sequence: inducer, draft proving, ignition, gas valve, flame sensing, then the blower. Combustion safety and the adopted fuel-gas code govern every step and setting.
- https://anvilfield.com/field-guides/hvac/fire-smoke-damper-installation-testing/ - Fire and smoke dampers are devices in HVAC ducts and openings that close to stop fire, heat, or smoke from spreading through a rated wall or floor where the duct breaks the barrier. Fire dampers close on heat, smoke dampers on a signal, combination dampers do both. Install per the listing; NFPA 80, NFPA 105, and the AHJ control.
- https://anvilfield.com/field-guides/hvac/fan-laws-affinity-airflow/ - The fan laws (affinity laws) predict how a fan's airflow, pressure, and power change with speed. Airflow varies directly with RPM, static pressure with the square of RPM, and shaft power with the cube of RPM. Slow a fan 20 percent and it draws roughly half the power, which is why variable speed saves so much.
- https://anvilfield.com/field-guides/hvac/fan-belt-drive-sheave-alignment/ - A belt-drive fan uses a motor turning one sheave, a fan turning a second sheave, and a V-belt between them. Fan speed equals motor speed times the motor sheave pitch diameter divided by the fan sheave pitch diameter. Belt tension and sheave alignment set belt and bearing life; the manufacturer's data controls the numbers.
- https://anvilfield.com/field-guides/hvac/evaporative-cooling-swamp-cooler-systems/ - Evaporative cooling lowers air temperature by evaporating water, which pulls heat out of the air and drops the dry-bulb toward the wet-bulb. A swamp cooler does this directly and adds humidity, so it works in hot dry climates and fails in humid ones. The local climate, the design wet-bulb, and the manufacturer's rating control the result.
- https://anvilfield.com/field-guides/hvac/ductwork-types-sheet-metal-flex-ductboard/ - Ductwork carries conditioned air from the air handler to the rooms, and the type you pick sets the leakage, the friction, the insulation cost, and where the duct fits. Galvanized sheet metal is the durable commercial standard. Round and spiral lose the least to friction and leakage. Flex and fiberglass ductboard cost less but suffer field abuse.
- https://anvilfield.com/field-guides/hvac/duct-leakage-testing-sealing/ - A duct leakage test pressurizes a sealed section of ductwork with a calibrated fan and orifice, then measures the airflow needed to hold the test pressure. That airflow is the leakage, compared against the SMACNA allowable from the duct's leakage class. ASHRAE 90.1 requires the test on duct operating above 3 in. w.g.
- https://anvilfield.com/field-guides/hvac/dedicated-outdoor-air-system-doas/ - A dedicated outdoor air system (DOAS) is a separate unit that conditions only the ventilation outdoor air, drying it to a low dewpoint to carry the building's latent load, while a parallel system handles the room sensible load. Decoupling ventilation from cooling fixes the part-load humidity a single mixed-air system cannot hold.
- https://anvilfield.com/field-guides/hvac/cooling-tower-types-operation/ - A cooling tower rejects building or process heat to the air by evaporating a small fraction of its water, cooling the condenser water a chiller dumps heat into. It can cool that water close to the ambient wet-bulb temperature but never below it. The design wet-bulb, the project specification, and the load control the selection.
- https://anvilfield.com/field-guides/hvac/condensate-neutralizer-condensing-appliance/ - A condensate neutralizer is a tube or chamber of media, usually calcium carbonate or magnesium oxide, that raises the pH of the acidic condensate a high-efficiency condensing furnace, boiler, or water heater produces before it reaches the drain. Many codes and manufacturers require it, especially on cast iron, concrete, or septic systems.
- https://anvilfield.com/field-guides/hvac/compressor-types-scroll-screw-reciprocating/ - A compressor is the pump of the refrigeration cycle. It raises low-pressure vapor to high pressure and moves it through the system, which is what makes heat flow. The four common types are reciprocating, scroll, screw, and centrifugal, each suited to a size range. The system, not preference, picks the type.
- https://anvilfield.com/field-guides/hvac/chiller-types-selection-centrifugal-screw-scroll/ - A chiller makes chilled water for a building or process. Chillers split two ways: by compressor (centrifugal, screw, scroll, reciprocating, or heat-driven absorption) and by heat rejection (air-cooled or water-cooled). Centrifugal water-cooled machines lead at large tonnage and efficiency, but the load, the energy source, and the manufacturer's certified rating control the pick.
- https://anvilfield.com/field-guides/hvac/chilled-water-vs-dx-cooling-comparison/ - Chilled water and DX are the two ways commercial buildings cool. DX (direct expansion) cools air directly with refrigerant in a coil in the airstream. Chilled water makes cold water at a central chiller and pumps it to coils. DX fits small to mid buildings; chilled water wins at large scale, but the load and the design control the choice.
- https://anvilfield.com/field-guides/hvac/chilled-water-pumping-primary-secondary-variable/ - Chilled water pumping configuration sets how water moves through the chillers and out to the coils. Primary-secondary runs a constant-flow loop through the chillers and a variable-flow loop to the coils, joined by a decoupler. Variable primary flow uses one variable-speed pump set through both, with a minimum-flow bypass protecting the chiller.
- https://anvilfield.com/field-guides/hvac/chilled-water-low-delta-t-syndrome/ - Low delta-T syndrome is when chilled water returns to the plant colder than design, so the temperature difference across the coils is too small. The plant pumps more water and often runs an extra chiller to move the same cooling, wasting pump and chiller energy and capping capacity. The cause sits at the coils and valves, not the plant.
- https://anvilfield.com/field-guides/hvac/building-pressurization-control-makeup-air/ - Building pressurization is the air pressure inside a building relative to outdoors, set by the balance of air coming in against air going out. Slight positive, often 0.02 to 0.03 in. w.c., is the common design intent, but project documents, the space type, and the adopted code control.
- https://anvilfield.com/field-guides/hvac/boiler-water-treatment-chemistry-blowdown/ - Boiler water treatment is the chemical and mechanical control of the water in a boiler or hydronic loop to stop scale, corrosion, and fouling. Treatment chemicals plus blowdown hold the water in spec. A steam boiler with constant makeup needs heavy treatment and steady blowdown; a closed hydronic loop usually needs only a one-time inhibitor dose.
- https://anvilfield.com/field-guides/hvac/boiler-types-fire-tube-water-tube-condensing/ - A boiler heats water or makes steam for heating or process loads. The types split by how heat and water are arranged: fire-tube runs hot gas through tubes in a water shell, water-tube runs water through tubes in the fire, cast iron bolts up in sections. Condensing models recover flue-gas latent heat when return water stays low.
- https://anvilfield.com/field-guides/hvac/air-handling-unit-ahu-components-operation/ - An air handling unit (AHU) is the indoor central air handler that conditions and moves air through a building's duct system. Air flows in as return plus outside air through a mixing box, filters, heating and cooling coils, then the fan into the supply duct. The manufacturer's data and the project design govern the sizing and setpoints.
- https://anvilfield.com/field-guides/hvac/air-curtain-door-heater-systems/ - An air curtain is a unit mounted over a doorway that blows a controlled high-velocity stream of air down across the opening, forming an invisible barrier that separates inside from outside while the door is open. It holds conditioned air in and keeps infiltration, insects, dust, and fumes out. The stream has to reach the floor to work.
- https://anvilfield.com/field-guides/hvac/water-source-geothermal-heat-pump/ - A geothermal (water-source) heat pump moves heat between the building and a buried ground loop or well water that stays near 45 to 70°F year round, so it runs at a higher COP than air-source and lasts longer. The loop type, length, flow, and antifreeze are sized to the soil and the manufacturer's data, not a rule of thumb.
- https://anvilfield.com/field-guides/hvac/vrf-system-commissioning-startup/ - VRF (variable refrigerant flow), also called VRV, runs one or more variable-speed inverter compressors feeding many indoor units through a shared refrigerant network, modulating capacity to each zone. Commissioning it is a documented procedure, not a startup switch, because the long piping, the weighed-in charge, the deep vacuum, and the auto-addressed controls all have to be proven.
- https://anvilfield.com/field-guides/hvac/vav-box-commissioning-airflow/ - A VAV box throttles supply air to a zone to hold its temperature, modulating the inlet damper between a minimum and a maximum airflow setpoint. Commissioning sets and verifies those setpoints and the control sequence so the zone stays comfortable and meets its ventilation minimum. The project specification and the ASHRAE Guideline 36 sequence control the setup.
- https://anvilfield.com/field-guides/hvac/steam-heating-system-trap-commissioning/ - Steam heating distributes heat by sending steam from a boiler to terminals, where it condenses and gives up its large latent heat, then returns as condensate. A steam trap passes condensate and air but holds live steam. Commissioning proves every trap works, the system vents, and warm-up makes no water hammer, with the manufacturer and ASME governing.
- https://anvilfield.com/field-guides/hvac/split-system-condenser-lineset-install/ - A split system is a central air conditioner or heat pump split into an outdoor condensing unit and an indoor evaporator coil or air handler, joined by a refrigerant lineset and control wiring. Install a matched AHRI-rated pair, braze under flowing nitrogen, pressure test, evacuate to about 500 microns, then verify charge by subcooling and superheat.
- https://anvilfield.com/field-guides/hvac/sheet-metal-duct-fabrication-installation/ - Sheet metal duct fabrication is building ductwork to hold its operating pressure without leaking, bulging, or drumming. SMACNA's HVAC Duct Construction Standards set the gauge, seam, joint, reinforcement, and seal from the duct's pressure class. The design sizes the duct; construction and the project spec decide whether the air reaches the room.
- https://anvilfield.com/field-guides/hvac/rooftop-unit-rtu-installation-startup/ - A rooftop unit (RTU) is a packaged HVAC system, DX cooling plus gas, electric, or heat-pump heating with its own fans and often an economizer, set on a roof curb. Startup verifies the curb seal, condensate trap, compressor rotation, refrigerant charge, airflow, and gas temperature rise, but the manufacturer's instructions govern every setpoint.
- https://anvilfield.com/field-guides/hvac/refrigerant-piping-line-sizing-design/ - Refrigerant line sizing sets the suction, liquid, and discharge pipe diameters so each line carries the charge with low enough pressure drop to protect capacity and high enough velocity to drag oil back to the compressor. Too small kills capacity; too large starves the compressor of oil. The equipment manufacturer governs the size.
- https://anvilfield.com/field-guides/hvac/refrigerant-leak-detection-recovery/ - Refrigerant leak detection is the process of locating where charge is escaping a sealed system, and recovery is pulling the remaining charge into a cylinder before you open it. Venting refrigerant is illegal under EPA Section 608. Find the leak, recover the charge, fix it, evacuate deep, then recharge.
- https://anvilfield.com/field-guides/hvac/refrigerant-charging-subcool-superheat/ - Charge a fixed-orifice or piston system by superheat and a TXV or EEV system by subcooling, because that reading is what tells you the charge is right for the metering device. Superheat is suction temperature above saturation; subcooling is liquid temperature below it. The equipment data plate and charging chart set the targets.
- https://anvilfield.com/field-guides/hvac/makeup-air-unit-kitchen-ventilation/ - A makeup air unit (MAU) is the supply fan that replaces the air a commercial kitchen hood exhausts, so the building does not go negative. Codes require makeup air once a hood exceeds 400 CFM, and the IMC has it run with the exhaust and stay within 10 degrees F of the space. Project documents and the adopted code control.
- https://anvilfield.com/field-guides/hvac/kitchen-hood-suppression-semiannual/ - A commercial kitchen hood suppression system is a wet-chemical fire system that protects the cooking appliances, hood, plenum, and exhaust duct from a grease fire. NFPA 96 requires a trained technician to inspect and service it every 6 months, replacing fusible links, confirming each nozzle still aims at its hazard, and testing actuation. The AHJ and manufacturer govern.
- https://anvilfield.com/field-guides/hvac/hydronic-system-balancing/ - Hydronic balancing sets the water flow in gallons per minute (GPM) through every coil and circuit to its design value, so each zone gets its heating or cooling, then documents it in a TAB report. Circuits are set with balancing valves, but the project specification and the manufacturer's valve flow data control the targets, not a rule of thumb.
- https://anvilfield.com/field-guides/hvac/hydronic-pump-installation-replacement/ - A hydronic pump, circulator or base-mounted, moves water through a heating or cooling loop, sized to deliver a design flow in GPM against the system head in feet. Select it so the duty point sits near the pump's best efficiency point, never oversized, with the manufacturer's curve and the project specification controlling the choice.
- https://anvilfield.com/field-guides/hvac/hydronic-makeup-water-glycol-treatment/ - A hydronic loop fails from what the water carries, not from the pipe: air, corrosion, scale, and freeze. The water side keeps it healthy with a make-up water assembly, an air separator, an expansion tank, glycol for freeze protection, and a corrosion inhibitor. Project specifications and the fluid manufacturer control the targets.
- https://anvilfield.com/field-guides/hvac/humidification-dehumidification-control/ - Humidity control keeps a space within a target moisture band, using humidification to add water vapor and dehumidification to remove it. In a data center, control dew point, not relative humidity, and hold the ASHRAE TC 9.9 recommended band. The project specification and equipment requirements set the actual limits.
- https://anvilfield.com/field-guides/hvac/fan-coil-unit-fcu-installation-commissioning/ - A fan coil unit (FCU) is a small terminal unit, a fan and a coil, that heats or cools one zone using hot or chilled water or direct-expansion refrigerant. Commissioning means flushing and balancing the water, setting the fan and airflow, proving the condensate drain and overflow, and stroking the valve against the thermostat.
- https://anvilfield.com/field-guides/hvac/energy-recovery-ventilator-erv-commissioning/ - An energy recovery ventilator (ERV) transfers heat and moisture between a building's exhaust air and the incoming outdoor air, so ventilation air arrives pre-conditioned and the cooling or heating load drops. Commissioning means balancing the outdoor and exhaust airflows and verifying measured effectiveness against the AHRI 1060 rating, not just confirming the wheel spins.
- https://anvilfield.com/field-guides/hvac/economizer-demand-control-ventilation/ - An air-side economizer uses cool outside air for free cooling when conditions allow, and demand-control ventilation modulates that outside air to match real occupancy. Both cut energy, and both fail silently when nobody commissions them. The high-limit setpoint, the minimum outside-air floor, and sensor calibration control whether they actually save.
- https://anvilfield.com/field-guides/hvac/ductless-mini-split-multi-zone-install/ - A ductless mini-split is an inverter heat pump split into an outdoor condensing unit and one or more indoor heads joined by a refrigerant lineset, with no ductwork. Connect the heads with flared, torqued joints, evacuate to about 500 microns, add charge for lineset over the factory length, and slope the condensate so it drains.
- https://anvilfield.com/field-guides/hvac/duct-design-friction-rate-manual-d/ - Manual D is ACCA's residential duct design procedure: it sizes every duct so the blower delivers each room its design airflow within the equipment's available static pressure. The friction rate, available static pressure times 100 divided by total effective length, in inches of water per 100 ft, is the budget you size every run against.
- https://anvilfield.com/field-guides/hvac/cooling-tower-commissioning-water-treatment/ - A cooling tower rejects building heat by evaporating water, cooling the condenser water the chiller dumps heat into. Commissioning proves it makes its thermal performance, measured as approach to the wet-bulb, while the water management plan keeps it from scaling up and from growing Legionella. The project specification and ASHRAE 188 control the program.
- https://anvilfield.com/field-guides/hvac/cooling-heating-load-calculation-manual-j/ - A Manual J load calculation is ACCA's room-by-room accounting of the heat a building gains in summer and loses in winter, in Btu per hour, that sets the equipment size. It separates sensible from latent load and replaces the square-feet-per-ton rule of thumb that oversizes systems. The project specification and adopted code edition control.
- https://anvilfield.com/field-guides/hvac/condensate-drain-trap-management/ - Condensate is the water a cooling coil pulls out of the air as it dehumidifies, and managing it means trapping the drain, sloping the line, and protecting against overflow. The drain must beat the coil's static pressure, run downhill to an approved point, and shut the unit down before a clog floods the space.
- https://anvilfield.com/field-guides/hvac/commercial-exhaust-fan-ventilation/ - Commercial exhaust ventilation removes odor, moisture, heat, and contaminants from spaces like restrooms, garages, and equipment rooms, and holds the building's pressure relationship by pulling stale air out so fresh air comes in. ASHRAE 62.1 and the mechanical code set minimum exhaust rates by space, but the adopted code edition and project documents control.
- https://anvilfield.com/field-guides/hvac/chiller-plant-startup-commissioning/ - Chiller plant startup and commissioning brings a water-cooled chiller and its chilled-water plant online and proves it makes its rated capacity in tons and its efficiency in kW per ton. The chiller's first start is run by the manufacturer's factory-authorized technician, which the warranty requires, after the contractor has proven water flow, power, and controls are ready.
- https://anvilfield.com/field-guides/hvac/chilled-beam-active-passive-commissioning/ - A chilled beam is a ceiling-mounted water coil that cools a space by convection with no fan in the room, doing sensible cooling only. Passive beams cool by natural convection; active beams induce room air across the coil with primary ventilation air. The chilled water stays above the room dew point, and a dedicated outdoor air system handles humidity.
- https://anvilfield.com/field-guides/hvac/boiler-startup-commissioning/ - Boiler startup and commissioning fires a commercial hot-water or steam boiler for the first time and proves the combustion, the water side, and the safety chain before it runs unattended. A boiler is a fired pressure vessel, so the startup tests the limits, the low-water cutoff, and the relief valve, while the manufacturer's procedure and the jurisdictional boiler inspector govern.
- https://anvilfield.com/field-guides/hvac/air-filtration-merv-iaq/ - Air filtration captures particulate to protect the coil and the people breathing the air, rated by MERV under ASHRAE 52.2 on a 1 to 16 scale. A higher MERV catches finer particles but adds pressure drop and fan energy, so the project spec and the equipment's static rating control the choice, not a default number.
- https://anvilfield.com/field-guides/hvac/air-balancing-report-procedure/ - Testing, adjusting, and balancing (TAB) measures and sets an air system so every space gets its design airflow, then documents it in a report the engineer and owner accept. Outlets are commonly balanced within plus or minus 10 percent of design, but the project specification and the TAB standard control the tolerance, not a rule of thumb.
- https://anvilfield.com/field-guides/hvac/duct-static-pressure/ - External static pressure (ESP), or total external static pressure (TESP), is the resistance the blower fights as it pushes and pulls air through everything outside the cabinet, measured in inches of water column (in. wg). Many residential PSC systems are rated for about 0.5 in. wg, but read the equipment's blower table, not the rule of thumb.

Calculators (12):
- https://anvilfield.com/calculators/air-changes-per-hour-cfm-calculator/ - Find the airflow for a target air change rate: CFM = room volume x ACH / 60, from floor area and ceiling height.
- https://anvilfield.com/calculators/ashrae-ventilation-rate-calculator/ - Find the breathing-zone outdoor air a space needs: Vbz = Rp x Pz + Ra x Az.
- https://anvilfield.com/calculators/cooling-tons-btu-calculator/ - Convert a cooling load to tons of refrigeration: tons = BTU per hour divided by 12,000.
- https://anvilfield.com/calculators/dew-point-calculator/ - Find the dew point from air temperature and relative humidity, and the surface temperature condensation forms at.
- https://anvilfield.com/calculators/duct-equivalent-diameter-calculator/ - Convert a rectangular duct to its equal-friction round diameter: De = 1.30 x (a x b)^0.625 / (a + b)^0.250.
- https://anvilfield.com/calculators/fan-pump-affinity-laws-calculator/ - Scale fan or pump flow, pressure, and power for a speed change using the affinity laws: flow with speed, pressure with the square, power with the cube.
- https://anvilfield.com/calculators/hvac-duct-airflow-calculator/ - Solve duct airflow and velocity from the duct size using continuity (Q = V x A): enter a round or rectangular duct and either the CFM or the velocity, and get the other.
- https://anvilfield.com/calculators/hydronic-load-gpm-delta-t-calculator/ - Find the heat load of a hydronic loop from flow and temperature difference: BTU/hr = GPM x 500 x delta-T, and tons = GPM x delta-T / 24.
- https://anvilfield.com/calculators/mixed-air-temperature-calculator/ - Find the mixed air temperature from the outdoor and return temps and the outdoor-air percentage.
- https://anvilfield.com/calculators/npsh-available-calculator/ - Find the net positive suction head available to a pump: NPSHa = atmospheric + static - vapor pressure - friction head.
- https://anvilfield.com/calculators/pump-brake-horsepower-calculator/ - Find pump brake horsepower from flow and head: BHP = (gpm x head x specific gravity) / (3960 x efficiency).
- https://anvilfield.com/calculators/sensible-heat-airflow-btu-calculator/ - Find the sensible heat an airstream carries: BTU/hr = 1.08 x CFM x the temperature difference.

Readiness checks (11):
- https://anvilfield.com/quizzes/cold-storage-facility-readiness/ - A 2 minute check on whether your refrigerated warehouse handles the floor heave, vapor drive, and ammonia risk a walk-in never faces, before the slab cracks or a leak shuts you down.
- https://anvilfield.com/quizzes/contractor-succession-exit-readiness/ - A 2 minute check on whether your business is built to transfer for real value, before the day you want out arrives and you find out it is worth less than you hoped.
- https://anvilfield.com/quizzes/epa-608-certification-practice/ - Ten questions across the Core section and all four certification types, the way the real EPA 608 exam splits the work.
- https://anvilfield.com/quizzes/hvac-commissioning-startup-readiness/ - A 2 minute check on whether an HVAC system will actually pass commissioning and run as designed, before the Cx agent and the owner find the problems.
- https://anvilfield.com/quizzes/iaq-monitoring-readiness/ - A 2 minute check on whether your IAQ monitoring uses good sensors, watches the right things, and triggers a real response, or just shows numbers.
- https://anvilfield.com/quizzes/kitchen-exhaust-nfpa96-readiness/ - A 2-minute check on whether the grease path, its fire protection, and the records are actually ready before the fire marshal walks it.
- https://anvilfield.com/quizzes/predictive-maintenance-readiness/ - A 2 minute check on whether your maintenance catches failures developing on the critical equipment, or just reacts after they break.
- https://anvilfield.com/quizzes/refrigerant-brazing-readiness/ - A two-minute check that catches the setup gaps that seed scale, hide leaks, and leave moisture in the system.
- https://anvilfield.com/quizzes/retro-commissioning-readiness/ - A 2 minute check on whether your existing building is tuned to work as intended, or quietly drifting and wasting energy.
- https://anvilfield.com/quizzes/rtu-startup-readiness/ - A 2-minute check that catches the curb, trap, rotation, airflow, charge, and rise gaps before you sign the startup sheet.
- https://anvilfield.com/quizzes/warranty-management-readiness/ - A 2 minute check on whether you track warranties, catch defects before they expire, and triage callbacks, or let the warranty year drift.

Comparisons (12):
- https://anvilfield.com/compare/air-side-vs-water-side-economizer/ - Air-side economizer vs Water-side economizer
- https://anvilfield.com/compare/centrifugal-vs-screw-chiller/ - Centrifugal chiller vs Screw chiller
- https://anvilfield.com/compare/chilled-water-vs-dx-cooling/ - Chilled water vs DX (direct expansion)
- https://anvilfield.com/compare/ducted-vs-ductless-mini-split/ - Ducted system vs Ductless mini-split
- https://anvilfield.com/compare/fire-tube-vs-water-tube-boiler/ - Fire-tube boiler vs Water-tube boiler
- https://anvilfield.com/compare/gas-vs-electric-furnace/ - Gas furnace vs Electric furnace
- https://anvilfield.com/compare/heat-pump-vs-gas-furnace/ - Heat pump vs Gas furnace
- https://anvilfield.com/compare/rtu-vs-split-system/ - Packaged RTU vs Split system
- https://anvilfield.com/compare/txv-vs-fixed-orifice/ - Thermostatic expansion valve (TXV) vs Fixed orifice (piston)
- https://anvilfield.com/compare/vav-vs-cav/ - VAV (variable air volume) vs CAV (constant air volume)
- https://anvilfield.com/compare/vrf-vs-split-system/ - VRF system vs Split system
- https://anvilfield.com/compare/water-cooled-vs-air-cooled-chiller/ - Water-cooled chiller vs Air-cooled chiller

Offline field apps (12):
- https://anvilfield.com/subapps/blowercfm/ - Airflow and commissioning checks for HVAC work.
- https://anvilfield.com/subapps/gaugegatedc/ - Duct gauge, leakage, layout, and balance records.
- https://anvilfield.com/subapps/hood-suppress-semiannual/ - Wet-chemical kitchen-hood semi-annual packets with nozzle maps, link clocks, cylinder date checks, signatures, and AHJ exports.
- https://anvilfield.com/subapps/chargeright/ - Offline superheat and subcooling calculator giving HVAC/R techs a charge PASS, ADD, or RECOVER verdict.
- https://anvilfield.com/subapps/dryerairflowproof/ - Measures commercial dryer airflow, static pressure, and lint restriction and prints a condition report.
- https://anvilfield.com/subapps/dryplans500/ - Sizes air movers and dehumidifiers for water-damage restoration with S500-derived room-by-room math.
- https://anvilfield.com/subapps/foodeq-gasket-finder/ - Measures and matches cooler and oven door gaskets and exports a clean parts-desk order list.
- https://anvilfield.com/subapps/fryergaspressurelog/ - Logs fryer, range, and oven gas manifold WC readings against targets with a before/after proof sheet.
- https://anvilfield.com/subapps/loopwright/ - Offline hydronic radiant design from room heat loss to loop lengths, GPM, and circulator match.
- https://anvilfield.com/subapps/shaftline-dc/ - Turns dial readings and machine dimensions into shim and slide moves for millwright shaft alignment.
- https://anvilfield.com/subapps/staticdoctor/ - Field app for residential and light-commercial HVAC airside service and install.
- https://anvilfield.com/subapps/titratesuite-dc/ - Converts drops to ppm, sizes loops and pumps, and charges chilled-water loops for water-treatment techs.

Printable pack: https://anvilfield.com/field-guides/hvac/pack/ - every HVAC threshold, spec, and code in one PDF

Field notes (17):
- https://anvilfield.com/blog/hvac-data-hall-humidifier-canister-drain-tempering-valve-overflow-pan-float-supply-strainer-cabinet-label-and-bms-alarm-point-photo-record-before-winter-turnover/ - A field record for tying a data hall steam or electrode humidifier cabinet, canister condition, water supply strainer, drain tempering valve, overflow pan float, labels, BMS alarm point, humidity status, exceptions, and winter turnover release together.
- https://anvilfield.com/blog/hvac-heat-pump-outdoor-unit-snow-stand-service-clearance-defrost-discharge-path-disconnect-label-and-pad-drainage-photo-record-before-winter-turnover/ - A field record for documenting a heat-pump outdoor unit before winter turnover, including snow stand height, service clearance, defrost drainage, roof drip exposure, disconnect label, pad drainage, and release limits.
- https://anvilfield.com/blog/hvac-filter-bank-differential-pressure-record-before-coil-freeze-up-review/ - A useful HVAC filter-bank packet ties the unit, filter stage, filter identity, installed condition, measurement points, gauge, fan mode, differential pressure, trend history, coil evidence, open causes, and release decision together before a frozen-coil review becomes a blame note.
- https://anvilfield.com/blog/hvac-hydronic-reheat-valve-command-and-coil-leaving-air-temperature-trend-record-before-ceiling-closeout/ - A useful hydronic reheat closeout packet ties the VAV box tag, controller address, valve command, actuator response, coil leaving-air sensor, BAS trend, hot-water readiness, access photos, exceptions, and retest notes together before ceiling access disappears.
- https://anvilfield.com/blog/hvac-static-pressure-before-duct-changes/ - A useful HVAC record ties the complaint, equipment, blower setting, filter, coil, measurement points, static readings, and after-change result together.
- https://anvilfield.com/blog/hvac-refrigerant-line-set-insulation-uv-jacket-wall-sleeve-condensate-drip-point-and-labeling-photo-record-before-owner-turnover/ - An HVAC field record for refrigerant line sets before owner turnover covers insulation continuity, exterior UV protection, wall sleeves, drain drip evidence, labels, and holds.
- https://anvilfield.com/blog/hvac-economizer-damper-status-record-before-free-cooling-complaint-review/ - A useful economizer packet ties the unit, complaint, outside-air conditions, enable logic, damper command, actual position, sensor values, BAS trends, actuator/linkage checks, alarms, overrides, photos, and release decision together.
- https://anvilfield.com/blog/hvac-kitchen-hood-exhaust-fan-and-make-up-air-interlock-functional-record-before-health-inspection/ - A useful health-inspection packet ties each hood, exhaust fan, make-up air unit, interlock, temperature control, balance report, failed condition, retest, photo, and release boundary together.
- https://anvilfield.com/blog/hvac-air-handler-freeze-stat-capillary-placement-setpoint-and-reset-access-photo-record-before-winter-operation-release/ - Before winter operation release, the record should identify the air handler, coil boundary, freeze stat model, capillary placement, support and bend condition, setpoint, manual or automatic reset type, reset access, BAS alarm response, damper and valve response evidence, exceptions, and release decision.
- https://anvilfield.com/blog/hvac-condensate-neutralizer-media-cartridge-label-ph-sample-drain-route-and-overflow-pan-photo-record-before-owner-turnover/ - A turnover record for condensate neutralizer media, cartridge labels, pH samples, drain routing, pump safety switches, overflow pans, photos, holds, and owner handoff.
- https://anvilfield.com/blog/hvac-make-up-air-unit-discharge-air-low-limit-sensor-freeze-alarm-and-outside-air-damper-photo-record-before-winter-startup/ - Before winter startup, the make-up air unit record should prove the discharge-air low-limit sensor, freeze alarm, outside-air damper, actuator, BAS trend, reset status, exceptions, and release decision are visible enough for operations to trust.
- https://anvilfield.com/blog/hvac-rooftop-unit-economizer-minimum-outdoor-air-damper-proof-and-actuator-linkage-photo-record-before-shoulder-season-operation/ - Before shoulder-season operation, the RTU economizer record should show the unit, served area, minimum outdoor-air command, damper proof, actuator and linkage photos, sensor trends, controller status, alarms, exceptions, and release decision.
- https://anvilfield.com/blog/hvac-duct-leakage-before-balancing/ - A useful pre-TAB leakage packet ties the test scope, pressure, allowable limit, measured flow, repairs, retest, and release status together.
- https://anvilfield.com/blog/hvac-vav-box-damper-command-and-airflow-pickup-tube-photo-record-before-ceiling-tile-install/ - A useful VAV pre-ceiling packet ties the box tag, controller address, damper command, observed stroke, airflow pickup tubes, high and low tubing, BAS readback, TAB status, photos, exceptions, and retest notes together before access disappears.
- https://anvilfield.com/blog/hvac-chilled-water-valve-command-and-coil-delta-temperature-trend-record-before-comfort-complaint-closeout/ - Before a comfort complaint is closed, trend the chilled-water valve command beside coil entering and leaving air or water temperatures, discharge air, space temperature, setpoints, fan status, chilled-water supply, alarms, timestamps, exceptions, and the closeout decision.
- https://anvilfield.com/blog/hvac-condensate-drain-trap-and-overflow-safety-switch-photo-record-before-ceiling-closeout/ - A useful ceiling closeout packet ties the air handler, primary drain, trap, slope, cleanout, auxiliary pan or secondary drain, overflow safety switch, leak test, corrections, and photos together.
- https://anvilfield.com/blog/hvac-chilled-water-pump-differential-pressure-sensor-tubing-and-isolation-valve-photo-record-before-seasonal-cooling-complaint-review/ - Before a seasonal cooling complaint review, the chilled-water pump DP record should show the sensor tag, high and low taps, tubing route, isolation and equalizer valve positions, bleed status, BAS point, pump command, setpoint, trend, exceptions, and review decision.