PTAC and PTHP package terminal units: a field guide

What is a PTAC unit, and where it fits

A PTAC, a packaged terminal air conditioner, is a self-contained heating and cooling unit that lives in a sleeve through an exterior wall and conditions one room. Everything is in the one box: the compressor, both coils, the fans, the heat, and the controls. Half the unit faces the room and half faces outside, so it rejects heat through the back without any refrigerant lines, drain pipe, or ductwork run to it. You set the sleeve in the wall once, and from then on the unit slides in and out as a chassis.

You have seen thousands of them without thinking about it. The unit under the window in a hotel room, with the long grille outside and the louvered front and knobs inside, is a PTAC. So is the one in the assisted-living room, the garden apartment, the dorm, the sunroom, and the small office that the central system never reached. The appeal is that each room is its own system. One unit fails and one room is down, not a floor.

Where a PTAC sits among the system families, packaged versus split, central versus per-zone, is laid out in the HVAC system types overview. The PTAC is the packaged, per-room end of that map: the whole refrigeration circuit in one cabinet, serving a single zone, with no field refrigerant work at all.

What is the difference between a PTAC and a PTHP?

A PTAC heats with an electric resistance strip. A PTHP, a packaged terminal heat pump, heats by running its refrigeration cycle backward to pull heat from outdoor air, and only falls back to an electric strip when it gets too cold for the heat pump to keep up. Both cool the same way. The difference is entirely in how they make heat, and it shows up on the power bill, not in the room.

An electric strip is 100 percent efficient and no better: every watt in becomes one watt of heat. A heat pump moves more heat than the electricity it draws, often two to three times as much in mild weather, because it is moving heat rather than making it. In a climate with real winters the heat pump still saves through fall and spring, then leans on the strip in the cold snaps. That backup strip is why a PTHP still has resistance heat inside it.

The decision turns on climate and heating hours. In a warm or mild climate the PTHP pays back its higher price quickly because the heat pump runs most of the season. In a cold climate the heat pump spends more time below its balance point and the strip does more of the work, so the payback stretches out. Run the heating hours for the actual location rather than assuming the heat pump always wins.

The parts of a PTAC: sleeve, chassis, grille, and front

Four assemblies make up an installed unit, and knowing which is which saves confusion on a service call. The wall sleeve is the steel box built into the wall. It is the only permanent part. The chassis is the working unit that slides into the sleeve, and it carries the compressor, the indoor and outdoor coils, both fans on a shared motor, the heat, and the refrigerant circuit, all factory-charged and sealed.

On the outside, the rear grille or louver covers the condenser end. It lets outdoor air through to the condenser coil while keeping rain, leaves, and birds out, and it has to keep the hot discharge air from rolling back into the intake. On the inside, the front cover snaps over the chassis and carries the return air opening, the supply louvers, the filter behind it, and the controls, whether that is a set of knobs, a touchpad, or a wall thermostat wired in.

The split is the whole point of the design. The sleeve and grille stay with the building. The chassis is the part that wears out and gets swapped. Because the chassis carries the entire refrigeration circuit, there is no field brazing, no vacuum to pull, and no charge to set, which is exactly why a property can keep these running with maintenance staff instead of a refrigeration crew on every call.

The wall sleeve and the standard opening

The wall sleeve is the steel box framed into the wall that the chassis slides into, and almost the entire PTAC market is built around one opening: 42 inches wide by 16 inches high. Stay with that standard and a chassis from nearly any major brand will fit the sleeve you already have, which is the feature that makes these units cheap to live with over decades.

Two things about the sleeve decide whether the install is any good. First is level and pitch. The sleeve has to sit level side to side and be pitched correctly front to back so condensate runs to the outside, not back into the room. Some manufacturers call for the sleeve dead level and rely on the chassis to manage water; others call for a slight pitch toward the exterior. Follow the unit's installation manual, because the two approaches are not interchangeable and guessing is how water ends up in the wall.

Second is the seal. The gap between the sleeve and the rough opening, and the joint between the sleeve and the chassis, both have to be sealed and gasketed. An unsealed sleeve lets outdoor air, water, and noise straight into the room and lets the conditioned air leak out around the unit, so the room never holds temperature and the bill climbs. Foam, gasket, and flashing at the sleeve are not optional trim. They are what makes the hole in the wall behave like a wall.

Electric strip heat versus heat pump, and the balance point

PTAC heat is electric resistance: a strip of heating elements, sized in kilowatts, that the air blows across. It is simple, it works at any outdoor temperature, and it is the most expensive heat you can buy because electricity is more costly per unit of heat than gas almost everywhere. Strip sizes commonly run from about 2.5 kW to 5 kW, which is part of what sets the unit's amp draw and the circuit it needs.

PTHP heat is a heat pump first, with the electric strip held in reserve. As long as the outdoor air is warm enough, the heat pump carries the load at a fraction of the strip's running cost. As it gets colder the heat pump's output falls while the room's demand rises, and the point where the two cross is the balance point. Below it the heat pump alone cannot keep up and the control brings on the strip to make up the difference.

This is why a PTHP is not a way to delete electric heat. It is a way to use the cheap heat pump for most of the season and the expensive strip only when the weather forces it. In a mild climate the strip barely runs. In a cold one it runs hard through winter, and the PTHP's advantage over a plain PTAC narrows to the shoulder seasons. Size the strip in the PTHP for the worst case anyway, because it has to hold the room on the coldest night when the heat pump is doing almost nothing.

The fresh-air vent damper

Most PTACs include a manual fresh-air damper, a small door behind the front cover that opens a path from outside into the return airstream so the unit can pull in outdoor air. Opened, it brings in ventilation air and provides a little make-up air to offset what bathroom and corridor exhaust pull out of the room. Closed, the unit just recirculates room air.

The damper is a tradeoff, and the field default is usually closed or barely cracked. Open it wide in summer and you are asking the unit to cool and dehumidify hot, humid outdoor air on top of the room load, which it often cannot keep up with, and the room runs warm and sticky. Open it in deep winter and you are heating cold outdoor air with the strip. The reasonable setting is a small, deliberate opening sized to the ventilation the room actually needs, not full open.

On a property, the dampers drift. Housekeeping bumps them, guests fiddle with them, and a unit that runs warm or humid often has a damper somebody left wide open. Checking the damper position is a thirty-second step on a no-cool call that gets skipped because nobody thinks to look behind the cover.

How does a PTAC handle condensate?

A PTAC manages condensate two ways, and most of the time it never sees a drain pipe at all. The indoor coil pulls water out of the room air, and that water collects in a base pan that drains toward the outdoor end. There a slinger ring on the outdoor fan picks the water up off the pan and flings it onto the hot condenser coil, where it evaporates. That is by design. The unit uses the waste water to help cool the condenser, which is part of how a small box rejects as much heat as it does.

The slinger only works if the water gets to it, and that depends on the pitch. The base pan and sleeve have to slope so condensate runs toward the outdoor end and the slinger, not toward the room. Set the sleeve backward, or let the building settle so it pitches inward, and the pan overflows toward the inside and you get water on the floor and in the wall. Confirm the slope at install and again on any leak call.

In high-humidity climates, or where the slinger cannot evaporate everything it picks up, you add a condensate drain kit. Most manufacturers sell a kit that matches their sleeve and pipes the overflow to a proper drain outside. Use the factory kit so the fittings and the pan connection actually match, and pitch the drain line so it runs. A drain line that sags or backs up just moves the leak somewhere harder to find.

How do you size a PTAC?

Size a PTAC to the room's load, not to the biggest unit that fits the sleeve. PTACs are sold in a tight range of capacities, commonly around 7,000, 9,000, 12,000, and 15,000 BTU per hour, and the right one matches the cooling and heating load of the room it serves. A typical hotel guest room lands in the 7,000 to 12,000 range depending on size, exposure, glass, and climate. Run the room load rather than guessing.

Oversizing is the more common mistake, and it costs comfort. A unit too big for the room cools the air to setpoint fast, satisfies the thermostat, and shuts off before it has run long enough to wring the humidity out. The room ends up cold and clammy, the compressor short-cycles, and the short cycling wears the unit and annoys the guest. Bigger is not better with a PTAC. A right-sized unit runs longer, holds humidity down, and lasts.

Undersizing has the opposite failure: the unit runs constantly and never quite catches up on a design day, and the heat strip works overtime in winter. Between the two, oversizing is the trap most people fall into because it feels safe. Treat the manufacturer's capacity tables and a real room-by-room load as the authority on size. The sleeve opening tells you what fits, not what the room needs.

The electrical: voltage, cord, and circuit

PTACs run on single-phase power, almost always 208 or 230 volts, and the unit is rated for that range because building service at the receptacle varies. The chassis comes with a factory cord and plug, and the plug type is matched to the unit's amp draw, which is set by the cooling size and, more so, by the kilowatt rating of the heat strip. A bigger strip means more amps and a different plug and circuit.

Modern PTAC cords are LCDI cords, leakage-current detection and interruption, which is the protection now expected on these plug-connected units. The plug is a NEMA configuration matched to the circuit: 6-20 plugs on 20 amp circuits and 6-30 on 30 amp circuits are common, with the exact one stamped on the cord. Do not change the plug to make it fit an existing receptacle. The cord, the plug, and the breaker are a matched set, and the manufacturer's electrical table and the adopted electrical code govern the circuit, the receptacle, and the protection.

Match the receptacle to the unit, not the unit to the receptacle. The trap on a swap is dropping a larger unit, often one with a bigger heat strip, onto the circuit and receptacle the old smaller unit used. Check the new chassis nameplate amps against the existing branch circuit and receptacle before it goes in. If the new unit draws more, the circuit and receptacle change too, and that is an electrician's call, not a slide-in.

Controls: unit knobs, wall thermostat, and energy management

PTAC controls come at three levels. The simplest is unit-mounted: knobs or a touchpad on the front cover that the occupant sets directly. It is cheap and self-contained, and it is what a budget property runs. The downside is that the only thing controlling the unit is whoever last touched it, so an empty room often sits heating or cooling to whatever the last guest left.

The next level is a wall thermostat wired to the chassis, which moves the sensor off the unit and onto a wall away from the supply air, so it reads the room rather than its own discharge. That alone improves comfort and cuts short cycling, because the thermostat is not sitting in the cold air the unit just blew out.

The top level is energy management. A ceiling occupancy sensor and a door switch tell the control whether the room is occupied, and the unit sets back to a wider deadband when the room is empty, then recovers when someone comes in. Tied into a hotel's property management system, the PMS, the controls can set back unrented rooms harder for deeper savings. Occupancy-based control on guest-room PTACs is a documented energy saver in hospitality, with reported savings that are large enough that energy-management retrofits often pay for themselves on a property with meaningful vacancy. Verify the savings for the specific property and control package rather than assuming a headline number.

Where PTACs and PTHPs are used

The hotel and motel guest room is the number-one home for the PTAC, and the reason is operational, not technical. One unit per room means a failure is one room out of service, the maintenance staff can swap a chassis without a refrigeration license, and the first cost per room is low. For a property with a hundred rooms, those three facts outweigh the efficiency penalty against a fancier system.

Senior living and assisted living lean on PTACs for the same per-room independence, plus the simple controls that residents can actually use. Apartments, condos, and dorms use them where there is no central plant and each unit pays its own power. Then there is the long tail: the sunroom or addition with no ductwork, the small office, the guardhouse, the modular classroom, the equipment or telecom room that needs steady cooling in a space too small to justify anything bigger.

What ties the list together is one room, one wall, one unit, and no plant. Wherever the building wants to condition a single space cheaply and keep it independent of everything around it, the PTAC is in the running. Where the building wants quiet, high efficiency, or multiple rooms off one outdoor unit, the comparison shifts to a ductless mini-split, covered in the ductless mini-split install guide.

What is the difference between a PTAC and a mini split?

A PTAC is one self-contained box in a wall sleeve. A ductless mini-split is a split system: an outdoor condensing unit connected by a refrigerant lineset to one or more indoor heads, with the noisy compressor outside and a quiet head in the room. That structural difference drives every practical tradeoff between them.

The PTAC wins on first cost and on replacement. The unit is cheaper, there is no field refrigerant work, and a worn chassis slides out and a new one slides in within an hour using the existing sleeve. The mini-split wins on comfort and operating cost. With the compressor outside, the indoor head is far quieter, often library-quiet against the PTAC's audible compressor and fan right there in the room. The inverter-driven mini-split is also markedly more efficient, so it costs less to run, and over years of operation that gap can repay its higher install cost.

The honest split is this: the PTAC is cheap, fast to install, fast to replace, and louder and less efficient; the mini-split is quieter, more efficient, and more expensive to buy and install. A hotel with a hundred identical rooms and existing sleeves usually keeps PTACs for the swap-out economics. An owner upgrading a few rooms where guests complain about noise, or chasing the power bill on a long-occupancy building, often moves to mini-splits. The mini-split install itself, the lineset, the evacuation, the charge, and the condensate, is its own job and is covered in the ductless mini-split install guide.

Replacing a PTAC: the slide-out chassis swap

Replacing a PTAC is usually a chassis swap, and this is the single biggest reason properties stay with them. The sleeve and the exterior grille stay in the wall. You shut off and unplug the unit, pull the front cover, back out the screws holding the chassis to the sleeve, typically two or three per side, and slide the old chassis out onto a cart. The new chassis of the same size slides into the same sleeve, gets screwed and sealed, plugs in, and runs. No brazing, no vacuum, no charge, no wall work.

The catches are weight and matching. A chassis can run around 100 to 120 pounds, so it is a two-person lift off a sleeve that may be at chest height, and dropping one is how a sleeve gets bent. On matching, confirm the new chassis suits the existing sleeve and the existing circuit. Standard 42 by 16 sleeves take standard chassis, but verify the depth and the brand's sleeve compatibility, and check the new unit's amps and plug against the receptacle before you order, especially if the heat strip size changed.

While the chassis is out is the only easy chance to inspect the sleeve. Look for rust, a sleeve that has lost its pitch, failed seals, and a corroded or damaged exterior grille. A new chassis in a rotted sleeve still leaks. If the sleeve is gone, that is a wall job, not a swap, and far better caught with the chassis already out than discovered after the new unit is leaking.

Maintenance: filter, coils, condensate, and fan

PTAC maintenance is mostly about airflow and water, and the filter is first. The filter is a washable or disposable element behind the front cover, and on a hotel unit it needs cleaning monthly or close to it, because guest-room units run hard and pull in dust, lint, and worse. A clogged filter starves the indoor coil of air, the room runs warm, the coil can ice, and the compressor works against a load it cannot move. Most warm-room complaints on a PTAC start at the filter.

Coils come next. The indoor coil collects what gets past the filter, and the outdoor coil collects pollen, dust, and the mineral scale the slinger leaves behind as water evaporates on it. A dirty indoor coil chokes airflow and a dirty outdoor coil wrecks heat rejection, and either one shows up as a unit that runs constantly and never quite cools the room. Pull the chassis or open the grilles, brush and wash the coils with coil cleaner, and straighten bent fins. General coil-cleaning technique carries over from any DX equipment.

Round it out with the water and the moving parts. Clear the base pan and the slinger area of debris so condensate drains and the slinger can pick it up, check any drain kit line for sags and blockage, and check the fan motor and blower for noise, dry bearings, and a wheel loaded with dirt. On a property, run this as a route: every unit on a schedule, filters monthly, coils and pan at least seasonally, so the failures show up on a clipboard instead of at the front desk.

Indoor air quality and the wet coil

The PTAC's own coil is a humidity problem waiting to be neglected. The indoor coil runs wet whenever the unit cools, and a cool, wet, dirty surface in a warm room is where mold grows. Add a dirty filter, a base pan that does not drain, and a fresh-air damper left open to humid air, and a guest-room unit can turn into the source of the musty smell the front desk keeps hearing about.

The defenses are dull and they work. Keep the filter clean so the coil stays clean and the airflow stays up. Keep the pan and the drain path clear so standing water does not sit in the unit between cooling cycles. Keep the fresh-air damper to a sensible opening so the unit is not fighting a flood of humid outdoor air it cannot dehumidify. A right-sized unit helps here too, because an oversized one short-cycles and never runs long enough to dry the coil and the room.

When a room smells musty and the housekeeping checklist is clean, look at the PTAC before you blame the carpet. The smell often lives in the unit, and it clears when the filter, the coil, and the pan get the attention they were supposed to get all along.

Noise: the compressor in the room

The PTAC's biggest comfort complaint is noise, and it is structural. The compressor and both fans are in the box in the room, a few feet from the bed, so the guest hears the compressor cycle on and off all night. A typical PTAC runs in the range of a quiet to moderate conversation, audible enough that light sleepers notice every cycle.

Some of the noise is fixable and some is not. A unit that rattles, buzzes, or drones worse than its neighbors usually has a real cause: a loose front cover or grille, a fan wheel out of balance or loaded with debris, a chassis not seated and screwed tight in the sleeve, or worn fan-motor bearings. Those are service items. The baseline compressor cycling, though, is the design, and no amount of service makes a box with a compressor in it as quiet as a mini-split head with the compressor outside.

If noise is the deciding complaint on a property, that is the case where a mini-split earns its higher cost, because moving the compressor outdoors is the only thing that truly fixes it. The ductless mini-split install guide covers that path.

Efficiency: EER and the PTHP advantage

PTAC and PTHP cooling efficiency is rated as EER, the energy efficiency ratio, which is cooling output in BTU per hour divided by watts drawn at a rated condition. PTAC EERs sit in the lower part of the HVAC range compared with high-end mini-splits, which is the efficiency price you pay for a cheap, self-contained box. The minimum efficiency these units must meet is set by federal DOE standards, and the actual rated numbers come from the manufacturer's data.

On heating, the PTHP is where the real savings live. An electric strip can never beat one watt of heat per watt of electricity. A heat pump moves more heat than the power it uses, often a multiple of it in mild weather, so a PTHP heating a room in fall or spring uses a fraction of the energy a strip would. Over a heating season in a mild climate that gap adds up to real money against a plain PTAC.

The honest framing: a PTAC will not match a good ductless system on efficiency, and a PTHP will not match it either, but a PTHP beats a strip-heat PTAC on heating cost everywhere the heat pump gets to run. Compare the rated EER and the heating performance from the manufacturer's published data for the specific models, not from a rule of thumb, and weigh the heating climate, because that is what decides whether the PTHP premium pays back.

Why is my PTAC not cooling or leaking water?

Start with airflow on a no-cool call, because the cheap causes are the common ones. A dirty filter or dirty coils choke the unit, and the room runs warm while the unit runs constantly. Pull the filter and check the coils first, every time, before anyone reaches for gauges. A fresh-air damper left wide open will also make a unit look like it cannot cool, because it is fighting hot outdoor air on top of the room load.

If airflow is clear and the room still will not cool, then it is the refrigeration side: a compressor that is not running, a failed capacitor or fan motor, or a chassis that has lost its charge. A sealed chassis that has leaked its refrigerant is usually a swap, not a field repair, which is the whole economic logic of the design. Confirm the unit has power and the right voltage at the receptacle before condemning the chassis, because a tripped breaker or a bad receptacle reads as a dead unit.

A water leak into the room is almost always pitch or drainage, not a refrigerant problem. The sleeve has lost its slope, or settled, or was set wrong, and condensate runs inward instead of out to the slinger. Check the level and pitch, clear the base pan and the slinger area, and check any drain kit line for a sag or a clog. No heat on a PTHP often means the heat pump is in defrost or below its balance point and the strip is doing the work, which is normal; no heat on either type with the strip dead is an electrical fault in the heat circuit.

Commissioning a new install

A PTAC install lives or dies at the sleeve, so commissioning starts there. Confirm the sleeve is level side to side and pitched per the manufacturer for drainage, that it is sealed to the rough opening so air and water cannot bypass it, and that the exterior grille is mounted so discharge air cannot recirculate into the intake. Get the sleeve right and most of the failure modes are already off the table.

Then the chassis and the power. Seat the chassis fully, screw it to the sleeve, and seal the chassis-to-sleeve joint so room air does not leak around the unit. Confirm the receptacle voltage and that the plug, cord, and circuit match the unit's nameplate amps, with the LCDI cord intact and the protection working. Set the fresh-air damper to the position the room actually needs rather than leaving it wherever it shipped.

Start it up and prove it. Run cooling and watch that it pulls the room down and that condensate drains out, not in. Run heat, and on a PTHP confirm both heat-pump and backup-strip operation. Set or pair the controls, whether knobs, a wall thermostat, or the energy-management sensors, and confirm the occupancy logic if the property uses it. The unit that gets a real startup is the one that does not generate a callback in week one.

PTACs in offices, guardhouses, and equipment rooms

Outside hospitality, the PTAC earns its keep on the small, isolated space that does not justify a real system. A guardhouse, a modular field office, a single back office, a small classroom: one wall sleeve and one unit conditions it, and it runs independent of whatever the main building is doing. The first cost and the swap-out simplicity are the same advantages that sell it to hotels, applied to spaces a central system would never reach economically.

Small equipment and telecom rooms are a special case, and here the limits matter. A PTAC can hold a small room with a steady internal heat load, and a PTHP gives you heat-pump heating for an unoccupied space in the shoulder seasons. But a PTAC is a comfort-cooling unit, not precision cooling. It cycles on a room thermostat, it has limited dehumidification control, and it is not built for the tight temperature and humidity bands a dense server room needs. For anything past a light, intermittent IT load, the room wants dedicated cooling sized and controlled for the heat it actually rejects, not a comfort PTAC pressed into duty.

The rule for these spaces is honest about scope. The PTAC fits the small, low-stakes, steady-load room cheaply. Push it past comfort duty into critical cooling and you are betting equipment on a unit that was never designed for the job.

What to document

A property full of PTACs is only as manageable as its records. Per unit you want the location, the brand and model, the capacity and the heat type and strip size, the sleeve and chassis details, and the install or last-replacement date, so a swap can be ordered right the first time without sending someone to read a nameplate behind a front cover.

On the service side, log the filter and coil cleanings, the electrical check, the condensate and pitch check, and any repair, because the maintenance route is what keeps the whole property running and the record is what proves it happened. When you replace a chassis, write down whether the heat strip size or the amp draw changed, because that is the detail that determines whether the circuit still suits the unit.

Common mistakes

• Oversizing the unit so it short-cycles, leaves the room cold and humid, and wears out early.
• Setting the sleeve without pitch or with the wrong pitch, so condensate runs into the room and the wall.
• Putting electric-strip-only PTACs where a PTHP would have saved real money on the heating season.
• Leaving the fresh-air damper wide open, so the unit fights humid or cold outdoor air and the room never holds.
• Dropping a larger unit on the old circuit and receptacle without checking the new nameplate amps and plug.
• Skipping the filter and coil route, so the room runs warm and the coil grows mold.
• Sealing the sleeve poorly, so air, water, and noise leak around the unit and the room never holds temperature.
• Calling a chassis dead before checking power and voltage at the receptacle.

Field checklist

Standards and references

PTAC and PTHP performance is rated under AHRI 310/380, the joint AHRI and CSA standard (CSA C744) for packaged terminal air conditioners and heat pumps, which fixes the rating conditions so capacities and EER from different brands can be compared on the same basis. When you read a unit's published capacity and EER, those numbers come from this rating method. Treat the manufacturer's published data as the authority on capacity, efficiency, and the heat-pump performance, and on the sleeve pitch and drainage requirement, which varies by brand.

Minimum efficiency for these units is set by federal DOE energy-conservation standards, and ENERGY STAR levels sit above the minimum. Use those to know the floor; use the manufacturer's data for the actual rated numbers on a given model. Refrigerant is also changing: under the EPA AIM Act phasedown, new PTAC and PTHP units are moving off R-410A to lower-GWP A2L refrigerants such as R-32 and R-454B, so confirm the charge type and the A2L service requirements on current models.

On the electrical side, the adopted edition of the National Electrical Code, NFPA 70, governs the branch circuit, the receptacle, and the protection for a plug-connected PTAC, including the LCDI cord now expected on these units. Code is adopted and amended by jurisdiction, so confirm the requirements against the adopted edition and any local amendments. Across all of it, three things decide whether the install holds up: pitch the sleeve to drain, size the unit to the room instead of the sleeve, and pick PTAC or PTHP on the heating climate.

Units and terms

PTAC equipment carries its own vocabulary, and the same idea shows up under different labels across a spec sheet, a sleeve carton, and a nameplate.

Capacity is given in BTU per hour, sometimes shortened to BTU or Btuh, and occasionally in tons, where one ton is 12,000 BTU per hour. Cooling efficiency is EER. Heat-strip size is in kilowatts, kW. The sleeve opening is in inches, with 42 by 16 the standard. Voltage is nominal 208/230V single phase. The plug is a NEMA configuration matched to the circuit amps, and the cord is an LCDI cord for leakage protection.

PTAC

Packaged terminal air conditioner: self-contained through-wall unit with cooling and electric-strip heat

PTHP

Packaged terminal heat pump: a PTAC that heats with a heat pump and falls back to electric strip

Wall sleeve

The permanent steel box in the wall, standard 42 by 16 inches, that the chassis slides into

Chassis

The sealed working unit (compressor, coils, fans, heat) that slides into the sleeve and gets swapped

Slinger ring

Ring on the outdoor fan that throws condensate onto the condenser coil to evaporate it

Balance point

Outdoor temperature where a heat pump's output equals the room's heat loss; below it the strip helps

EER

Energy efficiency ratio: cooling BTU per hour divided by watts drawn at the rated condition

LCDI cord

Leakage-current detection and interruption power cord, the protection expected on plug-connected PTACs

Related tools

Calculators and readiness checks for this work

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