Domestic hot-water recirculation temperature logs before balancing complaints

Direct answer

Before reviewing a domestic hot-water recirculation balancing complaint, the temperature log should include the building, system name, water-heater or plant ID, storage temperature, heater outlet temperature, master mixing-valve outlet temperature where used, recirculation pump status, pump control mode, timer or demand-control status, aquastat or sensor location, supply main temperature, return main temperature, branch or riser return temperatures, balancing valve tag and setting, check-valve and isolation-valve status, strainer status if known, complaint fixture, fixture runout length or dead-leg concern, point-of-use temperature, time-to-hot-water reading, no-draw or active-draw condition, measured flow or pressure where part of the balancing scope, thermometer ID and calibration status, measurement time, occupancy/use condition, control limit or design target, failed readings, corrections, recheck readings, open exceptions, reviewer, and release boundary.

The log should prove whether the complaint belongs to the recirculation loop, a branch balance issue, a pump or control issue, a mixing-valve issue, a dead-leg or fixture runout issue, a cross-flow issue, a heater capacity issue, or a point-of-use limiting device issue. It should capture the temperatures before anyone starts turning balancing valves so the complaint review is not based on a moving target.

Use this as documentation guidance only. The project documents, plumbing code, energy code, local health requirements, water-management program, water-heater manufacturer, mixing-valve manufacturer, engineer, commissioning agent, TAB provider, owner, AHJ, safety manager, and qualified plumbing contractor control the work. This article is not a plumbing design, water-management program, Legionella control plan, scald-prevention plan, medical guidance, code interpretation, balancing procedure, or permission to adjust water temperatures, valves, pumps, controls, or fixture devices.

Do not start by turning valves

A hot-water balancing complaint often starts with a simple sentence: this fixture is cold, this shower takes too long, this wing never gets hot, or this riser loses temperature overnight. That sentence is not enough to start adjusting the loop. First capture the condition that exists before the system is changed.

The initial log should identify the complaint location, the system serving it, the time of day, the occupancy condition, and whether the complaint occurs after a long idle period, during peak use, after a control schedule change, after maintenance, or after new work. A fixture that is slow after an overnight idle can point to a different issue than a fixture that goes cold during morning peak.

Balancing changes can hide the original problem. If a branch valve is opened, a pump speed is changed, or a mixing-valve setpoint is moved before readings are taken, the team may lose the evidence that separates a bad balance from a failed check valve, closed isolation valve, plugged strainer, wrong control schedule, excessive dead leg, or fixture-level temperature limit.

Tie the log to the control basis

Every temperature log needs a target, but the target cannot come from a generic note. Name the controlling basis: design documents, water-management program, commissioning plan, TAB procedure, code requirement, owner standard, manufacturer startup sheet, local health requirement, or engineer direction. If different areas have different limits, record the correct one for the measured point.

CDC guidance for Legionella control says building water programs should monitor temperature and identify slow-moving water, and its hot-water guidance says hot water should be stored above 140 degrees F, circulation should not fall below 120 degrees F, and anti-scald regulations must still be followed. Those are public-health control references, not a license to override local code, fixture limits, or a water-management program.

ASHRAE Standard 188 is presented by ASHRAE as establishing minimum legionellosis risk management requirements for building water systems. ASHRAE's risk-management page also states that Standard 188 includes requirements for building water system design, including documentation, balancing, and commissioning. For a complaint packet, that means the log should connect readings to the program or project basis that controls the building, not to a guess made at one fixture.

Map the loop before judging it

A recirculation complaint cannot be evaluated from one lavatory reading alone. The packet should show the water heater or plant, storage tank, master mixing valve if present, supply main, return main, recirculation pump, branch returns, balancing valves, check valves, isolation valves, risers, fixture groups, and known long runouts.

The map does not need to be pretty. It needs to be useful. Mark the complaint fixture, the closest recirculated source, the branch or riser return serving it, the farthest branch return, any known dead legs, and any new work that changed piping, valves, insulation, controls, or fixtures. If the drawings do not match the field, photograph the field tags and mark the difference.

The DOE/PNNL hot-water temperature-maintenance review describes traditional hot-water recirculation as moving hot water through the system and returning it to the source through a dedicated loop and pump. It also classifies return-loop pipe segments as mains, subloops, and dead-leg branches. That is exactly why the complaint packet should identify whether the measured fixture is on the loop or beyond it.

Log plant and mixing-valve status first

Start at the source. Record water-heater enable status, storage temperature, heater outlet temperature, storage-tank sensor reading if available, master mixing-valve outlet temperature, mixing-valve setpoint, recirculation return connection, pump status, pump speed, timer or demand-control status, BAS command, aquastat setpoint, and any alarm or lockout.

ASSE's temperature-control device guideline says ASSE 1017 temperature-actuated mixing valves for hot-water distribution systems are used for controlling inline water temperatures in domestic hot-water systems, are installed at or near the hot-water source, are designed to provide relatively uniform water temperature to the distribution system, and are not intended for point-of-use applications. The same guideline says further downstream mixing may be needed for final temperature control and scald protection.

That distinction belongs in the log. A complaint at a lavatory should not automatically become a master mixing-valve adjustment. If the distribution setpoint, point-of-use limiting device, shower valve, ASSE 1070 device, or other fixture-level protection is part of the issue, record which device is being measured and which device the complaint review is allowed to adjust.

Separate loop readings from fixture readings

Loop readings and fixture readings answer different questions. A return-main temperature can show whether the loop is generally hot. A branch return temperature can show whether one riser is lagging. A fixture reading can show what the user experiences after the final runout, local mixing, fixture device, aerator, shower valve, or dead-leg volume.

Keep those readings in separate rows. For each point, record tag, location, thermometer ID, contact or immersion method, start time, stabilization time, no-draw or draw condition, temperature, and whether the reading is before adjustment, after adjustment, or after recheck. If a fixture reading includes a time-to-hot-water measurement, record the starting temperature, ending temperature, flow condition, and elapsed time.

CDC's monitoring guidance specifically notes that measuring the time it takes for hot water to reach maximum temperature can indicate how quickly or efficiently hot water travels in the system. That supports adding wait-time evidence to the complaint packet while keeping it distinct from loop balancing readings.

Record pump controls and demand logic

A cold complaint can be a control complaint. Record whether the recirculation pump is continuous, scheduled, aquastat-controlled, BAS-controlled, demand-controlled, disabled, in hand mode, in alarm, or running at a different speed than expected. Include the time clock schedule, sensor location, command status, and whether the pump actually runs when the log says it should.

ICC hot-water safety guidance summarizing 2021 code changes says heated-water circulation systems are provided with circulation pumps and controls that turn off the pump when the loop is at the desired temperature and there is no demand, with demand recirculation controls starting the pump on a user, presence, or flow signal. The exact adopted code varies by jurisdiction, but the record lesson is stable: the complaint review should show the control state when the temperature was measured.

Do not let a balancing valve absorb a control problem. If the pump is off by schedule, the aquastat sensor is in the wrong location, the BAS point is overridden, or the demand signal is not reaching the controller, the packet should hold the balancing release until controls are corrected and rechecked.

Branch returns show balance better than guesses

A branch return schedule is the heart of a recirculation balancing complaint. Measure the return main and each relevant branch or riser return before changing settings. Record the valve tag, measured temperature, target or allowable range, current handwheel or memory-stop setting, capillary or thermostatic element setting if applicable, and whether the valve is manual, fixed-flow, pressure-dependent, or thermostatic.

ASPE's hot-water return material says a properly balanced recirculation system results in the same temperature drop at each balancing valve, and that balancing valves can be adjusted by manual, fixed-calibration, or thermostatic means. DOE/PNNL similarly explains that balancing valves are used because water follows the path of least resistance, and that they throttle return-loop segments to balance heat losses across the system.

The complaint packet should therefore show the branch comparison. If one return is much cooler than adjacent returns, the issue may be flow through that branch. If all returns are low, the issue may be plant temperature, pump status, control schedule, heat loss, or system-wide demand. If the loop is hot but the fixture is not, the issue may be past the recirculated source.

Use no-draw readings when the issue is recirculation

A recirculation balance check usually needs a no-draw condition, or at least a clearly documented draw condition. If fixtures are actively using hot water while readings are taken, the measured temperatures can reflect demand, mixing, and recovery instead of loop balance. Record whether the system was at idle, normal use, peak use, or a controlled test condition.

Caleffi's recirculating domestic hot-water guide gives a manufacturer example where bridge and return valves around a point-of-distribution mixing valve are adjusted when there is no domestic water draw on the recirculating loop, with the technician monitoring the temperature leaving the mixing valve until it remains stable. That is product-specific guidance, but it illustrates a broader documentation point: state the operating condition before interpreting the reading.

If no-draw testing is impossible because the building cannot be taken out of use, say that. A complaint review can still collect useful readings, but it should not pretend those readings are the same as an idle balance. Use the release boundary to separate preliminary diagnosis from final balancing.

Watch for cross-flow and local mixing

Hot-water complaints are not always cold-loop complaints. Cross-flow through a failed check valve, fixture cartridge, hose station, mixing valve, or connected equipment can push cold water into hot piping or hot water into cold piping. A local limiting device can also cap point-of-use temperature even when the loop is healthy.

ASSE's guideline warns that installing the wrong temperature-control device or installing it in the wrong location can create serious scalding situations or a false sense of security. It also recommends supplementary check valves where needed to prohibit cross-flow through devices that do not include integral checks. Those points support documenting check-valve status and fixture-level controls before changing system balance.

The log should record symptoms that point away from balance: hot water showing up on the cold side, a cold-water temperature that rises during recirculation, a single fixture behaving differently from nearby fixtures on the same branch, a shower valve that will not pass the expected mixed temperature, or a complaint that follows one device rather than one riser.

Use calibrated readings, not hand feel

Hand feel is not a temperature log. Record thermometer type, asset ID, calibration or verification date, measurement method, contact location, insulation removed or left in place, stabilization time, and whether readings are from a gauge, BAS point, immersion measurement, strap-on probe, infrared reading, or fixture outlet.

NEBB describes testing as measuring and documenting airflow, pressure, temperature, and other relevant parameters, adjusting as fine-tuning components such as valves and fans, and balancing as distributing air and water flow throughout the system. It also emphasizes instrument and calibration requirements for certified firms. Even when the complaint is not a formal TAB job, the record should still be repeatable.

If a permanent gauge disagrees with the field thermometer, record both. Do not silently choose the number that supports the preferred fix. A mismatch between BAS trend, analog gauge, mixed outlet thermometer, and branch return reading may be the finding.

Decide release, limited release, or hold

The complaint review should end with a status. Released to balancing means the plant, controls, measurement method, and known valves are ready for the balancing scope named in the record. Limited release means balancing can continue on named branches while listed exceptions remain open. Held means valve adjustment should not proceed until a design, controls, water-management, fixture, safety, or access issue is resolved.

Use holds without apology. Hold for no control target, unknown water-management limit, pump not running, mixing valve unstable, missing access to balancing valves, untagged branches, suspected cross-flow, failed check valve, cold-water return path, dead-leg issue, scald-control review, failed thermometer verification, or measurements taken during uncontrolled demand.

The strongest packet leaves the next person with a clear boundary: which branches can be adjusted, which readings must be rechecked, which fixtures are outside the loop, which devices need qualified review, and whether the complaint is resolved, improved, unresolved, or outside the balancing scope.

Minimum balancing complaint packet

Use the commissioning plan, TAB forms, water-management logs, manufacturer startup sheets, owner work order system, and project quality forms first. Add this field packet where those records do not connect the complaint, recirculation loop, temperatures, valves, controls, and release decision clearly enough.

Before balancing complaint checklist

Run this check before a domestic hot-water recirculation complaint is released for balancing adjustment.

• Confirm the complaint fixture, room, riser, fixture type, time of complaint, and owner work order.
• Attach or reference the design target, water-management limit, commissioning plan, TAB scope, owner standard, code basis, and manufacturer instructions that control the review.
• Record water-heater enable status, storage temperature, heater outlet temperature, alarms, lockouts, and recovery condition.
• Record master mixing-valve outlet temperature, setpoint, return connection, point-of-use limiting device status, and any scald-control hold.
• Record recirculation pump status, speed, timer, BAS command, demand signal, aquastat setpoint, sensor location, and whether the pump is in auto, hand, off, or alarm.
• Mark the loop map with supply main, return main, branch returns, risers, balancing valves, check valves, isolation valves, strainers, complaint fixture, and known long runouts.
• Take before-adjustment readings at the supply main, return main, farthest return, complaint branch return, and nearby comparison branch returns.
• Record whether readings were taken at no draw, normal draw, peak draw, controlled draw, or unknown draw condition.
• Record balancing valve tag, valve type, handwheel or memory-stop setting, thermostatic setting where applicable, and access condition before adjustment.
• Take point-of-use readings separately from loop readings, including start temperature, final temperature, elapsed time, flow condition, and local temperature-control device.
• Check for symptoms of cross-flow, failed checks, cold-water warming, fixture cartridge issues, hose connections, and device bypass.
• Record thermometer ID, calibration or verification status, method, and any disagreement between gauge, BAS, and field thermometer.
• Document each correction, then remeasure the same points under comparable conditions.
• State whether the complaint is resolved, improved, unresolved, outside the loop, controls-pending, design-pending, water-management-pending, fixture-pending, or held.

Weak and strong notes

Weak note: Hot-water loop adjusted. Complaint fixed.

That note does not identify the fixture, loop, control basis, source temperature, mixing status, pump status, branch returns, valve settings, measuring instrument, no-draw condition, correction, recheck, or release boundary.

Stronger note: Domestic hot-water recirculation complaint review for Level 4 east lavatory L4-18, served by DHW Loop B and branch return BR-B-4. Owner ticket P-226 reported long wait and lukewarm water after overnight idle. Control basis is commissioning plan Cx-DHW-2, owner water-management limit WMP-7, and engineer email dated 2026-06-09. At 6:05 a.m. before adjustment, storage tank read 143 degrees F, heater outlet field reading was 141 degrees F, master mixing-valve outlet was 128 degrees F, BAS point was 127 degrees F, recirculation pump P-DHW-B was in auto and running at 62 percent, and aquastat was calling. No draw was observed for 10 minutes before branch readings. Return main was 123 degrees F. Branch returns BR-B-1, BR-B-2, and BR-B-3 read 122 to 124 degrees F. Complaint branch BR-B-4 read 111 degrees F at balancing valve BV-B-4, which was one turn open with memory stop loose. Nearby fixture L4-17 reached 119 degrees F in 18 seconds; complaint fixture L4-18 reached 108 degrees F after 90 seconds. Check valve CV-B-4 was warm on both sides but return pipe downstream stayed cool. BV-B-4 strainer was removed by plumber, found partially blocked, cleaned, reinstalled, and valve reset to three turns open under engineer-approved adjustment. Recheck at 7:10 a.m. under no draw showed BR-B-4 at 122 degrees F and L4-18 reaching 119 degrees F in 26 seconds. Release is limited to BR-B-4 complaint correction. It does not change master mixing setpoint, water-management limits, point-of-use device settings, or final TAB report acceptance.

The stronger note works because it separates the complaint fixture from the loop, records before-adjustment temperatures, names the control basis, preserves valve and pump status, shows the correction, and limits the release.

Common mistakes

The first mistake is adjusting the nearest balancing valve before taking source, loop, and fixture readings. That can erase the evidence that shows whether the valve was the problem.

The second mistake is treating a fixture temperature as a loop temperature. A local limiting device, shower valve, cartridge, dead leg, or runout can change what the user sees after the loop is already hot.

The third mistake is raising a master mixing-valve setpoint to solve a local complaint without a scald-control and water-management review. Distribution temperature and point-of-use protection are separate control questions.

The fourth mistake is ignoring pump controls. If the pump is off, scheduled down, demand-controlled, overridden, or using the wrong sensor, balancing may chase a control problem.

The fifth mistake is comparing readings taken under different demand conditions. No-draw readings, peak-use readings, and fixture draw readings should not be mixed without explanation.

The sixth mistake is accepting hand feel. A complaint review needs repeatable temperatures, instrument ID, measurement method, and recheck readings after correction.

Questions that come up

Should the log use CDC temperatures as the pass/fail target? Use the building's controlling water-management program, project documents, code, owner requirements, and qualified reviewer direction. CDC guidance is an important public-health reference, but it does not replace local limits or project-specific control points.

Can one cold fixture prove the recirculation loop is out of balance? No. One fixture can indicate a complaint, but the loop diagnosis needs source, return, branch, valve, pump, and nearby comparison readings.

Do point-of-use temperature devices belong in a balancing log? Yes, when they affect the complaint. Record them separately from loop temperatures so the review can distinguish distribution balance from fixture-level limiting.

Should balancing be done during active use? Sometimes the project or TAB plan may require specific operating conditions. If readings are taken during active use, document the condition and do not label them as no-draw balance readings.

What if the water-management program and the balancing target conflict? Hold the release and get direction from the responsible owner, engineer, water-management team, AHJ, and qualified reviewers. Do not resolve that conflict by field adjustment alone.

Related tools

LogEye fits repeated hot-water temperature readings where the same points need trend evidence before and after corrections.

FreshTest can support separate water-quality sampling records when the complaint review is tied to a water-management program.

Backflow Fix-It belongs in a separate record when cross-flow, checks, or device bypass may be part of the complaint.

SetupCheck can help when pump controls, BAS points, schedules, sensors, and setpoints need a pre-review setup checklist.

Compliance and safety limits

This field note is not a plumbing design, water-management program, Legionella control plan, infection-control procedure, scald-prevention plan, code interpretation, energy-code interpretation, TAB procedure, commissioning plan, medical guidance, manufacturer startup procedure, warranty approval, or permission to adjust water heaters, storage tanks, thermostats, mixing valves, point-of-use limiting devices, shower valves, balancing valves, check valves, pumps, timers, aquastats, BAS controls, strainers, fixtures, or distribution piping. The project documents, plumbing code, energy code, local health requirements, water-management program, engineer, commissioning agent, TAB provider, owner, AHJ, safety manager, manufacturers, and qualified plumbing contractor control the work.

Do not use this checklist to bypass scald protection, fixture maximum-temperature limits, anti-scald regulations, water-management control limits, lockout/tagout, electrical safety, confined-space rules, hot-water burn protection, PPE, access controls, ladder controls, ceiling access rules, public protection, infection-control requirements, chemical treatment requirements, or site-specific safety procedures. Do not raise temperatures, defeat limiters, bypass checks, disable controls, or change pump operation without the required authorization and qualified review.

Sources checked

• CDC, Monitoring Building WaterUsed for hot-water temperature monitoring, circulation-temperature guidance, anti-scald caution, time-to-maximum-temperature observation, disinfectant residual context, and slow-moving water risk.
• CDC, Developing a Water Management Program to Reduce Legionella Growth and Spread in BuildingsUsed for water-management control measures, control limits, control points, corrective actions, documentation, communication, and verification by reviewing temperature logs.
• ASHRAE, Guidance for Water System Risk ManagementUsed for ASHRAE's description of water-system risk management, Standard 188 water-management requirements, documentation, balancing, commissioning, and building water system risk context.
• ASHRAE, ANSI/ASHRAE Standard 188-2021 Legionellosis: Risk Management for Building Water SystemsUsed for ASHRAE's description that Standard 188 establishes minimum legionellosis risk management requirements for building water systems and applies to design, construction, installation, commissioning, operation, maintenance, and service.
• ASSE International, Guidelines for Temperature Control Devices in Domestic Hot Water SystemsUsed for temperature-control device distinctions, ASSE 1017 distribution mixing-valve context, point-of-use limits, scald-protection caution, device-location warnings, and check-valve/cross-flow context.
• International Code Council, Week three Building Safety Month event covers hot water safetyUsed for ICC hot-water safety and 2021 code-change context around temperature limiting, circulation pumps, demand controls, desired loop temperature controls, and hot-water pipe insulation.
• American Society of Plumbing Engineers, Hot Water Return Systems and ApplicationsUsed for hot-water return pump, balancing valves, same-temperature-drop concept, manual/fixed/thermostatic balancing valve distinctions, heat-loss equilibrium, and return-temperature context.
• U.S. Department of Energy, Hot Water Temperature Maintenance System OptionsUsed for domestic hot-water temperature maintenance overview, traditional hot-water recirculation, mains/subloops/dead-leg branches, balancing valves, pump role, heat-loss balance, and troubleshooting context.
• Caleffi, idronics 21: Recirculating Domestic Hot Water SystemsUsed as manufacturer technical context for recirculating hot-water heat loss, bridge and return valve adjustment, no-draw conditions, stable mixing-valve outlet temperature, and multi-branch balancing.
• NEBB, Testing, Adjusting and BalancingUsed for testing, adjusting, and balancing definitions around measuring and documenting temperature and other parameters, adjusting valves and controls, balancing water flow, reporting, and instrument calibration context.

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