Heat pump system inspection, basics of operation, troubleshooting & repair guide. This article series answers most questions about heat pump system troubleshooting, inspection, diagnosis and repair. We explain how heat pumps work to provide cooling in hot weather and heating in cool or cold weather.

We explain the concept of coefficient of performance or COP, and how the COP balance point determines how much use can be made of a heat pump in different climates.

Heat Pump System Inspection, Diagnosis, Repair - Troubleshooting & Repair Articles

This article describes how to inspect residential heat pump systems (combination heating and cooling systems) to inform home buyers, owners, and home inspectors of common heat pump system defects.

We discuss: How a Heat Pump Operates to Extract Heat from Outdoor Air When in Heating Mode = Winter Mode. Troubleshooting backup heat problems on heat pump systems that provide both air conditioning and heating. How to determine heat pump capacity.

What is the COP or Coefficient of Performance of Heat Pumps? What is the COP balance point for heat pump designs? Heat pump system components and parts and a comparison of air, water, and ground source heat pump designs. How does a Triple Split System Heat Pump System operate?How does a Bi-Valent Heat Pump System Work?

The articles at this website describe the basic components of a heat pump system, how heat pumps are inspected, diagnosed, and repaired, and we discuss how to estimate the rated heating and cooling capacity of a heat pump system by examining various data tags and components.

The limitations of visual inspection of HVAC systems are described as well.

[Click to enlarge any image]

If you are not at all familiar with heat pumps see this list of definitions:

• HEAT PUMP GLOSSARY [PDF] courtesy of Greenfoot Energy Solutions, Moncton - 43 Driscoll Crescent, E1E 4C8 Canad, Tel: (506) 383-3446 Email: Web: https://www.greenfootenergy.ca Tel: 1 (844) 213-2471 Website: retrieved 2022/01/18 original source: https://www.greenfootenergy.ca/resources/heat-pump-glossary
  
  Greenfoot Energy Solutions, an energy auditing company advertising the provision of un-biased information, has offices in a numer of Canadian cities.

Heat Pump Operating Principles

The schematic of a heat pump system shown above and the sketch at left are compliments of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

A "heat pump" is an air conditioning system that can work in either of two directions.

During the cooling season

 the heat pump moves heat from inside the building to outdoors by removing heat from indoor air - by blowing indoor air across the evaporating or cooling coil.

During the heating season

 the same equipment reverses the direction of its operation, scavenging heat from outdoor air and moving it into the building - by blowing indoor air across a warmed condensing coil, and by blowing outdoor air across the outdoor coil.

Controls in the heat pump reverse the operation and flow of the refrigerant in order to change the direction of heat movement between the indoor and outdoor areas.

Since most components of a heat pump system are identical with those of central air conditioning systems, readers should also be sure to review our air conditioning system inspection, diagnosis, and repair articles.

Below we expand the explanation of how a heat pump works in summer - cooling mode and how a heat pump works in winter - heating mode.

How the Heat Pump Works When in Cooling Mode = Summer Mode

Below we illustrate the heat pump operation when the equipment is in heating mode.

In cooling mode the heat pump works like a conventional air conditioner. The indoor cooling coil expands liquid refrigerant into a gas form, cooling the coil. Indoor air is cooled by being blown across the indoor cooling coil (left side of the Carson Dunlop Associates' image).

Outside the refrigerant gas is compressed to high pressure high temperature gas, then sent through the outdoor condensing coil where outdoor air blown across the condensing coil condenses the refrigerant back to a liquid for its return to the indoor components.

Even though the outdoor air may be hot during the cooling season, it is at a lower temperature than the outdoor condensing coil - so the system works to transfer heat from indoors to outside.

See the next two illustrations for more detail about this process when we switch to heating mode.

 

How a Heat Pump Operates to Extract Heat from Outdoor Air When in Heating Mode = Winter Mode

Illustrations above & below provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Additional Controls for a Heat Pump

We have said often that a heat pump is pretty much like an air conditioner, with a few control differences to allow the system to reverse its direction of heat movement between the indoor and outdoor areas.

In an air conditioner the outdoor coil is used only to cool and condense high temperature high pressure refrigerant gas back to a liquid refrigerant, and the indoor coil is used only to expand the liquid refrigerant to a gas (through an expansion device such as a Thermostatic Expansion Valve (TEV) or a capillary tube (Cap Tube).

But because a heat pump has to be able to work in both directions, its indoor and outdoor coil have to be able to exchange roles. To accomplish this the heat pump will need two refrigerant metering and expansion devices, one at each coil.

Only one of the expansion devices is operating at a given time - depending on whether the equipment is operating in a heating or in a cooling mode.

Illustration provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Reversing Valve and Defrost Cycle Operation Procedure for Heat Pumps

In addition to the two expansion devices, the system may make use of a reversing valve that changes the direction of flow of refrigerant gas and liquid in the system.

An additional set of controls for operation the refrigerant reversing valve and the operation of the defrost cycle for a heat pump are illustrated at left. During a defrost cycle

1. The reversing valve changes direction of the refrigerant flow to send warmed refrigerant "freon" to the outdoor coil in order to melt ice that may have formed there.
2. During the defrost cycle the outdoor fan stops - we want to stop moving outdoor air across the outdoor coil in order to allow the warm refrigerant to warm the coil.
3. If the system includes electric heating elements, one stage of the electric
   
   BACKUP HEAT for HEAT PUMPS
   
   may be activated in the blower compartment to warm air coming off of the blower.
   
   If the system does not include electric backup heaters, the indoor air handler blower will stop during the defrost cycle so that we don't' blow wrong-temperature air into the occupied space.

Illustration provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Details about reversing valves are found at REVERSING VALVE on HEAT PUMPS

What is an "All Electric" Heat Pump System? - Compared with Gas or Oil Backup Heat

The operation of the outdoor compressor/condenser unit and the indoor air handler blower assembly unit is normally run by electrical power.

When the back-up heat for a heat pump operated building is also all electric we refer to the installation as an all-electric heat pump installation. All electric heat pump systems are suitable where electrical energy costs are low or where the number of heating degree days in the local climate is modest.

See BACKUP HEAT for HEAT PUMPS for a discussion of how a heat pump electric backup heat system is tested.

For locations subject to very cold winter weather with many heating days during which outdoor temperatures are below the balance point for heat pump operation, building owners typically use a fossil-fuel backup heat such as natural gas, propane, or heating oil, and may heat by an integrated furnace or by a separate heating system.

Illustration provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

How does a Water Source Heat Pump System Work?

The operation of a water source heat pump system depends on accomplishing its temperature change by using water from a well, or more generally from a pair of wells.

Some water source heat pumps use one or a cascade of water storage tanks. In a water storage tank design, well water is pumped into the storage tank and the heat pump continues to pump heat into the water or take heat from the water (depending on summer or winter mode operation) until the temperature of the water no longer permits an efficient energy exchange.

At that point the energy exchange available in the tank of water has been exhausted - the tank is pumped back into a discharge well, or in some older designs, into another destination.

More details about measuring the efficiency or COP and EER of ground water heat pumps are found

at HEAT PUMPS, GROUNDWATER

Illustration provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

How does a Ground Source Heat Pump System Work?

For a simple understanding of all heat pump systems, air, water, or ground-sourced, it helps to understand that we are always moving heat back and forth between the heat pump and the air, water or ground. The differences are in the medium of exchange, not in the basic system operation and controls.

The operation of a ground sourced heat pump system is described by the illustration at left.

Unlike the water based heat pump operation, the ground sourced heat pump system uses a loop of pipes buried in soil to exchange heat with the ground; a separate tank system or discharge well system is not required.

Illustration provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

 

 

Sketch of a Triple Split System Heat Pump System

The sketch above illustrates how a triple split system heat pump is organized.

The compressor motor is installed and located as a separate component inside the building while the other system components (outdoor coil and indoor coil) remain in their traditional locations.

Illustration provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

How does a Bi-Valent Heat Pump System Work? Three Operating Modes all using the outdoor coil

The operation of a bivalent heat pump is not as confusing or intimidating as the name might sound.

[Click to enlarge any image]

A bi-valent heat pump installation adds this term to handle three different heat pump operating conditions:

1. Cooling mold - the system works as the heat pumps described earlier in this article
2. Heating mode 1. In moderately-cool outdoor temperature conditions during which the outdoor temperature does not drop below a preset level, typically 38 degF. the heat pump provides heat to the building without resorting to a backup heat system.
3. Heating mode 2. In colder outdoor conditions when the outside temperature is below the set point (we're using 38 F.) an auxiliary or backup heating system (such as LP or natural gas burners) operates to warm the outdoor coil that in turn is used to deliver heat to the occupied space.

Illustration provided by Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

What is the COP or Coefficient of Performance of Heat Pumps?

The COP or coefficient of performance describes the ability of a heat pump to extract heat from outdoor air down to some low temperature, typically 25 degF. for modern equipment. The COP determines how effective a heat pump can be at providing heat during cool or cold weather.

Details including a definition of COP, an explanation of the heat pump balance point, and how to calculate heat pump operating cost more accurately by considering degree days are at HEAT PUMP COP - Definition, sources of variation in heat pump operating efficiency & cost

Heat Pump operating cost variables & COP Calculations

Where a heat pump is used to provide part of the building's heat requirements, the efficiency of the air-to-air heat pump will be less at lower temperatures. Spies (1971, 1977) [2] notes that heat pump efficiency when outdoorr air is warm is quite different from at cold temperatures, making its use of electricity more complex.

The coefficient of utilization may be as high as 3.0, falling to 1.0 as outdoor temperature approaches 10 degF. In 1971 when Spies wrote that note for the Small Homes Council, few heat pumps worked at temperatures that low,

Also that this was in 1971, newer equipment is capable of efficient heat extraction from colder air. Spies provided a calculation to transfer heat pump efficiency or COP into electrical costs when comparing heating fuel type cost alternatives:

Notes to the table above

• Henry Spies, "Fuels & Burners", Small Homes Council - Building Research Council Circular Series #G3.5, 1971. 1977

Example: If you live in a climate in which the average number of degree days in the heating season is 4000, then to compare heat pump operating costs (using electricity) to other fuels and heating methods,

divide your current electricity cost (say 5 cents per kwh) by 2.2.

5 / 2.2 = 2.27 cents / kwh

Heat Pump Stopped Heating or Cooling - Diagnostic Guide

If your heat pump system has lost its cooling capacity or won't start select one or more of the diagnostic articles listed below.

• A/C REFRIGERANT LEAK DETECTION: how to use a TIF5000 to detect air conditioning refrigerant gas leak
• A/C DIAGNOSTIC FAQs: air conditioning system diagnostic FAQs: Q&A about air conditioner repair - a detailed air conditioning system diagnostic checklist
• AIR HANDLER UNIT: problems with the air handler, air filters, and the cooling coil itself
• BACKUP HEAT: on heat pumps, types of backup heat; problems with backup heat; begin here if your heat pump is not providing enough heat or if your air conditioning system provides heat when it should be providing cooling.
• COMPRESSOR CONDENSER: problems with air conditioner compressor/condenser units including noises and compressor hard-starting repairs
• A/C - HEAT PUMP CONTROLS & SWITCHES: air conditioner controls and switches - begin here if your A/C won't start.
  
  Here's an important tip: most refrigeration problems, in air conditioners, refrigerators, or freezers, are electrical, not mechanical. In air conditioning school, we used to drive out and collect abandoned refrigerators that people were tossing out during our community's spring cleanup week.
  
  Taking these appliances back into the shop we found that almost always the problem that had caused the owner to dispose of their air conditioner or freezer was in an electrical connection or electrical control. So it's worth checking out switches and controls on an air conditioner before replacing more costly components.
• DEHUMIDIFICATION PROBLEMS - Air conditioner cools but does not dehumidify
• DUCT SYSTEM DEFECTS: problems with the air duct system, air filters, supply registers, return air registers
• FIRE DAMPERS, and Heating and Cooling Air Duct Controls such as manual and automatic duct dampers, zone dampers, and fire dampers are discussed and distinguished
  
  at DRAFT REGULATORS - barometric damper
• LOST COOLING CAPACITY: what to do when not enough cool air comes out of the system - the articles in this series also assist in diagnosis of lost heating capacity for heat pump systems.
  • WHAT TO CHECK FIRST if there is no cool air or not enough cool air
  • COMPRESSOR FAILURE DIAGNOSIS basic checks of the air conditioner compressor
  • DUCTS & AIR HANDLER DIAGNOSI : basic checks of the indoor air handler (blower), air ducts, and filter system
• OPERATING DEFECTS: major air conditioning problem symptoms and how to get the air conditioning system working again,e.g. compressor or fan noises, failure to start, and inadequate cool air volume
• ZONE DAMPER CONTROLS . discusses manual and automatic air duct zone controls

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-04-14 - by (mod) -

@Green Leaf Air,

Thank you

I think you're making the point that we should make it for you to find the basic diagnostic procedures when an air conditioner heat pump is not working including suggestions about what to check first.

I've made a stab at that but I see it's perhaps not sufficiently easy to find. In the article above there's a section entitled

• HEAT PUMP STOPPED HEATING OR COOLING - DIAGNOSTIC GUIDE - basic starting points for troubleshooting a heat pump system

If your heat pump system has lost its cooling capacity or won't start select one or more of the diagnostic articles listed below.

There we list the key diagnostic starting points for any of the series of common problems including no cooling or no output or fan or compressor condenser problems. Please take a look and meanwhile I will also edit the page above to try to make those Diagnostics easier to find.

Thanks for the comment

On 2021-04-14 by Green Leaf Air

Heat Pump Stopped Heating or Cooling - Diagnostic Guide. WHAT TO CHECK FIRST if there is no cool air or not enough cool air. COMPRESSOR FAILURE DIAGNOSIS basic checks of the air conditioner compressor.

On 2021-03-02 - by (mod) -

re-posting without dis-allowed advertising link

Kopernikas Green · 4 minutes ago

Nice article. You said very well. I read this article and find some important point that is very helpful for me. Thank you very much for sharing

On 2021-02-17 - by (mod) -

Clover

Your pasting of our texts work just fine as a comment. Of course if you have questions, criticism, or content suggestions I would be very glad to hear them and to respond.

On 2021-02-17 by Clover Rayner

Heat pump system inspection, basics of operation, troubleshooting & repair guide. This article series answers most questions about heat pump system troubleshooting, inspection, diagnosis and repair. We explain how heat pumps work to provide cooling in hot weather and heating in cool or cold weather.

On 2021-02-04 - by (mod) -

Thank you for the note, Clover,

you're quite correct - and those as well as all of our articles on this topic are found in the ARTICLE INDEX

eg DIRTY COOLING COIL / EVAPORATOR COIL at https://inspectapedia.com/aircond/Clogged_Evaporator_Coil.php

and its cousin DIRTY AIR FILTER PROBLEMS https://inspectapedia.com/aircond/Dirty_Clogged_Air_Filter.php

On 2021-02-04 by Clover Rayner

An evaporator coil or cooling coil: typically the cooling coil is a section of finned tubing (it looks a lot like a car radiator) into which liquid refrigerant is metered and permitted to evaporate from liquid to gas state inside the coil.

This state change of the refrigerant, from liquid to gas, absorbs heat, cooling the evaporator coil surface and thus cooling indoor air blown across the cooling coil. Usually the cooling coil is located inside the air handler. See AIR HANDLER UNIT and articles like DIRTY COOLING COIL.

On 2021-02-03 - by (mod) -

Green,

Thank you so much for the generous remark. We have been developing and tuning InspectApedia.com for nearly two decades now; on occasion I've tried hiring "experts" but have been disappointed that sometimes people who offer design services have a lot of opinion but no actual training, no data and less expertise than we'd have expected.

A background in publishing and computer hardware and software design for users helps as does the plethora of user comments.

So we much welcome also any questions, criticism, or suggestions you may have. Working together with actual data makes us smarter than reliance on "alternative facts".

On 2021-02-01 by Green Leaf Air

I’m truly enjoying the design and layout of your blog.

It’s a very easy on the eyes which makes it much more
pleasant for me to come here and visit more often. Did you
hire out a developer to create your theme?
Excellent work!

On 2019-12-16 by (mod) - heat pump repair steps

RE-Posting:

This Q&A were posted originally

at ELECTRICITY TURN ON AFTER BREAKER TRIP


2019/12/16 Dorothy asked:

My heat pump was making the room hotter; it had gotten up to 71 and going higher (I had the thermostat set at 64, manual mode). To stop the persistent blowing heat I threw the breakers controlling the heat pump, depriving it of power.

I haven't had any heat for days and it's cold in here. I want to try re-starting the heat pump but want to know how to avoid damaging the system. (I'm thinking the system may "re-boot" if I put the power back on; is this possible?). Please advise how to safely re-start the power to the heat pump system.


Moderator reply:

Dorothy

HOW to GET HEAT if the HEAT PUMP IS NOT WORKING

If your thermostat has a setting for "EMERGENCY HEAT" switch that ON; that will turn on your backup heating system.

To be clear, "emergency heat" should normally be turned on ONLY if the heat pump itself fails or won't run.

HOW TO TURN the HEAT PUMP BACK ON IN COLD WEATHER - AFTER a POWER LOSS or POWER WAS TURNED OFF

EXPLANATION of why we don’t just turn the heat pump back on and call for heat:

When your heat pump has been OFF for several hours or longer in cold weather, you do NOT want to simply turn everything back on so as to ask the outdoor compressor unit to run. That’s because when the compressor has been off in cold weather if you suddenly turn it back on and ask it to run, liquid refrigerant may enter the compressor motor, damaging or ruining it

. That’s called “liquid slugging” at the compressor. Normally when the heat pump has electrical power a small electric heater right on the compressor motor keeps it warm in cold weather so that any refrigerant entering the compressor is in gas form, not liquid form. That prevents liquid slugging damage.

DO THE FOLLOWING:

When power to your home is on (if it was off, say due to a power failure)

1. Set the thermostat to EMERGENCY HEAT. That will give you heat while we’re waiting for the heat pump’s own internal heater to warm it up to avoid damage to the compressor motor.

2. WAIT at least six hours. (The specific amount of time you really need to wait depends on the heat pump brand and model and the outdoor temperature; you may see specific advice in your heat pump operating manual or you can call the manufacturer’s consumer help line to ask that guidance).

If you have no other information, wait at least six hours after having restored electric power to the home and to the heat pump circuit.

3. SWITCH the thermostat back to normal HEAT mode and your heat pump system should be ready to operate.

4. LISTEN: if you hear an ongoing horrible rattling banging or screaming noise coming from the outdoor compressor-condenser unit turn the system back off and call your HVAC company for repair.


MORE INFORMATION on How to use your heat pump and our list of heat pump diagnostic procedures begins at

HEAT PUMPS inspectapedia.com/aircond/Heat_Pump_Repairs.php


About the problem you had that started all of this: HEAT PUMP WOULD NOT TURN OFF:

It sounds as if there might be a short between thermostat wires (or a bad heater control board or relay)

Details on how to debug that problem are at THERMOSTAT WON'T TURN OFF inspectapedia.com/heat/Thermostat_Stuck_On.php

On 2017-05-25 by (mod) - more causes of sump cycling or backups

David

What clever detective work - new ideas to add to our inventory of sump cycling or backups.

I'm guessing we see this comment here because of the suspicion that a geo-thermal heat pump water source is sending water where it shouldn't.

Indeed if your geothermal tapped into an artesian well water source then there needs to be a well spool or seal in the casing that keeps well water below the well casing top and perhaps below a pitless adapter. If the spool has failed or is missing then the well could, if there's a leak anywhere in that system, pushing water out to a handy nearby destinatino.

About the roof drain system, I don't know your home - we don't usually run roof drainage into a seepage pit near the building, unless we needed a sump system because the building is at a flat or low spot where there is no chance to drain by gravity to get water away from the home. In any event, if you've gone for a week with no rain and the water problem continues I suspect it's not roof drainage.

It may be possible to look into the flooding seepage pit to see where water is entering it: from the incoming roof drain versus from the pit sides from ground flooding from a leaky artesian well.

Watch out: never work alone and don't lean over any seepage nor septic or drywell pit without appropriate safety gear: falling in can be fatal.

Keep me posted.

On 2017-05-24 by David

We installed leader drain pipes and connected 2 sump pumps to the leader drains from the basement to two seepage pits about 3 weeks ago.

Since that time, the rear right side corner seepage pit has been backing up and overflowing, creating a pool of water around the rear right corner of the foundation and property. A geothermal well is located several feet away from the right side seepage pit.

Our site contractor sent his crew out to the house yesterday to diagnose the problem with the back right corner leader drain/seepage pit.

They opened the lid on the seepage pit and it is was completely full of water, which indicates that the water is indeed reaching the pit and it is not an issue with the piping that was installed leading to the pit. The other seepage pits had either no water or a minimal amount of water inside of them and are draining properly.

We came up with 2 potential issues that could be causing the seepage pit to fill up and not drain appropriately.

The first could be the that amount of water that is coming out of the gutter/leader at that section plus the water being pumped out of the rear Sump pump is substantial and causing the 500 gallon seepage pit to fill up and overfllow.

A potential solution to this would be to connect the 2 seepage pits in the rear yard with a pipe which would allow for the water from the pit that is filling up to overflow into the other pit which is not filling up, relieving the excess flow. Although if both pits then start to overflow after we connect a pipe between them, then that could mean we need larger pits to manage the total amount of water coming off the roof and from the foundation in that area.

The 2nd potential issue would be a more substantial concern if it were to be true.

And that is if one or both of the well pipes from the Geothermal system are leaking into the seepage pit (which is pretty close to one of the Geothermal wells) and causing the pit to overflow.

When the well was dug, a steady flow of water came up from the borehole until it was packed with sealant. Could this leak have resprung under ground pressure? Is "artesian" water leakage from a geothermal well bore common?

On 2016-04-02 by (mod) -

A reversing valve stuck

On 2016-04-01 by Garrett

What would cause the system to pump itself into a vacuum in a/c mode but works in heat mode?

On 2016-01-26 by mike,a.v.ca.

heat wont kick on beow freezingunless i turn off and on again then runs only few minutes?

On 2016-01-24 by (mod) -

Sorry but I can't diagnose your heating system's trouble from just your e-text, Chris. I suggest that a qualified HVAC repair person is needed, on site.

On 2016-01-19 by Chris

I live in Manchester NH, have a California Heat pump , when I turn the heat on , it works for few minutes then starts to blow air. I call the maintenance they turn it off and start again , works for few minutes then starts to pump cold air , any response is appreciated

On 2016-01-17 by Greg from Ky

Our outside unit has frost/ice on the evaporator coils, what is the problem and how can I correct this problem?
The outside temp. when I saw this was 33 and it has got colder now outside.

On 2016-01-02 by (mod) -

Dirk:

Check the FAN ON setting at your thermostat and check for another FAN ON switch on the limit switch in your heater blower unit (if there is one);

If that doesn't fix the trouble search InspectApedia.com for FAN WON'T STOP to see how to diagnose and fix the trouble.

On 2016-01-01 by Dirk Zollinger

I have a Lennox heat pump with 2 heating, 1 cooling about 2 years old. I live in Texas, and we have only had a couple days of 32 or below. Our heater and fan run constantly. I am in a fairly solid brick home. Is there a reason for this?

On 2015-10-13 by KENT TURNER

I have a Ruud achiever 11 super high efficiency heat pump the how low can i set the heat pump before it turns off can it be set to 28 degrees and if so will it turn off and not keep running.>

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: will adding a hard-start kit on a heat pump increase the heat output in winter?

(Oct 21, 2011) richie said:
if a hard start kit is installed on a 3 yr old goodman heat pump, 2.5 ton, will it give any extra heat in the winter months ahead?

Reply:

(June 26, 2012) Chad the AC Guy said:
Richie, the hard start kit was installed to help the compressor on start up and will not increase or decrease your tonage nor the heat output of the system.

Thanks Chad - Editor.

Question: low side pressure drops in a 410a Heat Pump

(July 4, 2012) mike said:
410a heat pump has a good charge but while the system is running the low side pressure starts dropping until the system freezes up. could this be a bad expantion valve. pressure went from 150psi to under 100psi in less than 10 minutes. head pressure almost 400

(Nov 10, 2012) robert said:
Heil heapump blew a transformer in the air handler

Reply: water in the system freezes the TEV / TXV; heat pump freeze-ups

To Mike -it sounds to me as if you have moisture in system; it freezes internally in the thermostatic expansion valve - TXV Valve - and ice restrictsrefrigerant flow or can keep the valve from opening when it should.

You will need to recover refrigerant, replace filter dryer, pull deep vacuum till reach 500 micron level and recharge system with virgin refrigerant.

Anonymous:

Perhaps your heat pump is failing to enter its defrost cycle, or the compressor heater in the outdoor unit is not working.

Question: outside unit won't turn on

(Aug 9, 2012) Dave said:
inside air handler is running, outside unit will not come on
have low voltage to outside unit, new contactor, new themostat
Goodman units heap pump

Reply:

We can't diagnose this one from just your note, Dave. Your service tech will start by checking for power, then check relays and controls. Let's hope it's not the compressor itself.

Question: Heil air handler transformer blew

(Nov 10, 2012) robert said:
Heil heapump blew a transformer in the air handler

Question: Carrier heat pump condenser fan won't keep running

(Jan 15, 2013) Ted said:
Carrier heat pump turns on and runs but the condensor fan motor turns off after a few minutes but the compressor continues to run. Naturally, the air out of the vents starts to cool off. The run cap and condensor fan motor are new but the condensor fan motor gets hot when running and even hotter once it shuts off

. Only thing I can think of is defroster control board but it is only a couple of years old and wouldn't really explain why the motor runs so hot. Any thoughts?

Question: high pitched running water sound in pipes on call for heat

(Jan 16, 2013) PAD said:
I have 50 year old 24 unit building with force hot water heating. I have one unit that has a high pitched sound running through the pipes when the unit calls for heat. The zone valve is fine. I have tried reducing the water going into the pipes by partially closing the valve so not as much pressure is going into that unit. It is the farthest from the boiler.

The boiler guys says it might be pressure going through the elbows of the pipes but after reading up on this could it be lime/deposit build up? When I drained some of the water it was very dirty (I drained it because I thought it might have air in the lines, but it didn't).

Reply:

Pad please see HEATING SYSTEM NOISE DIAGNOSIS

Question: American Standard Heritage 14 seer Heat Pump. my error code is flashing 2.

(Feb 5, 2013) Mikesanders421 said:
I have an American Standard Heritage 14 seer Heat Pump. my error code is flashing 2. I recently replaced the defrost control board because it would not activate the fan to kick into high rpm mode. fan seems to run constantly in outside unit and thermostat cycles between heat and auxiliary heat mode. the nights are 15-25 degrees and the days between 40-50. does my unit seem to be operating normal or should I call for service

Reply:

2-flashes typically indicates a fault with the defrost system. I'd shut the system off and call for service; if we run the compressor in this condition it may be damaged.

Question: intermittent failures in air handler, then too much heat

21 Feb 2015 cindy said:

We have something very strange going on with our heat and air unit for almost a year now. It seems to happen during the more extreme heat or cold. The unit will work intermittently. Yesterday I had lukewarm air during the day, heating the house to 65. Suddenly last night it started working, heating the house to 70.

As I was sitting here this morning I can feel times where it is blowing cold air(very cold air!) I have tried to find a pattern but there doesn't seem to be one.

Sometimes it blows cold air when it switches to auxiliary heat, sometimes not. We were renting the house this summer but the renter basically described the same thing for the cooling system. We have had our HVAC guy out on several occasions and he has replaced various things but we continue to have problems. Any advice?

Reply:

Some things to check

Loose or shorted thermostat wires

Failing control board

Bad thermostat

Question: funny smell and heat is on, outside unit not running

24Feb 23015 Anonymous said:
came home funny smell in house. heat still on but fan on outside not running.warm heat coming up from where fan is

Reply:

Anon

Perhaps the smell is from your backup heat turning on. Check that odor source.

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Continue reading at DEFECTS LIST - HEAT PUMP or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• DIAGNOSTIC GUIDE A/C or HEAT PUMP - diagnose air conditioner or heat pump not working
• AIR CONDITIONING & HEAT PUMP SYSTEMS - basic components of air conditioners and heat pumps.
• APPLIANCE EFFICIENCY RATINGS - how efficient is your heat pump? also
  
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Suggested citation for this web page

HEAT PUMPS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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