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Air Source Heat Pumps
There are two common types of heat pumps: air-source heat pumps and geothermal heat pumps. Either one can keep your home warm in the winter and cool in the summer. An air-source heat pump pulls its heat indoors from the outdoor air in the winter and from the indoor air in the summer. A geothermal heat pump extracts heat from the indoor air when it’s hot outside, but when it’s cold outside, it draws heat into a home from the ground, which maintains a nearly constant temperature of 50° to 60°F.
An air-source heat pump can provide efficient heating and cooling for your home, especially if you live in a warm climate. When properly installed, an air-source heat pump can deliver one-and-a-half to three times more heat energy to a home compared to the electrical energy it consumes.
This is possible because a heat pump moves heat rather than converting it from a fuel, like in combustion heating systems.
How They Work
You might be wondering how an air-source heat pump uses the outdoor winter air to heat a home. Believe it or not: heat can be harvested from cold outdoor air down to about 40°F. And this can be accomplished through a process you’re probably already familiar with — refrigeration.
Basically, a heat pump’s refrigeration system consists of a compressor and two coils made of copper tubing, which are surrounded by aluminum fins to aid heat transfer. The coils look much like the radiator in your car. Like in a refrigerator or air-conditioner, refrigerant flows continuously through pipes, back and forth from the outdoor coils. In the heating mode, liquid refrigerant extracts heat from the outside coils and air, and moves it inside as it evaporates into a gas. The indoor coils transfer heat from the refrigerant as it condenses back into a liquid. A reversing valve, near the compressor, can change the direction of the refrigerant flow for cooling as well as for defrosting the outdoor coils in winter.
When outdoor temperatures fall below 40°F, a less efficient panel of electric resistance coils, similar to those in your toaster, kicks in to provide indoor heating. This is why air-source heat pumps aren’t always very efficient for heating in areas with cold winters. Fuel-burning furnaces generally can provide a more economical way to heat homes in cooler U.S. climates.
The efficiency and performance of today’s air-source heat pumps is one-and-a-half to two times greater than those available 30 years ago. This improvement in efficiency has resulted from technical advances and options such as:
♦ Thermostatic expansion valves for more precise control of the refrigerant flow to the indoor coil
♦Variable speed blowers, which are more efficient and can compensate for some of the adverse effects of restricted ducts, dirty filters and dirty coils
♦ Improved coil design
♦ Improved electric motor and two-speed compressor designs
♦ Copper tubing, grooved inside to increase surface area.
Types of Air-Source Heat Pumps
You can use a central heat pump to heat and cool a whole house. Most central heat pumps are split-systems — that is, they each have one coil indoors and one outdoors. Supply and return ducts connect to a central fan, which is located indoors. The fan, often called an air handler or blower, circulates air throughout the house. The fan also usually contains electric resistance coils (some units now have a gas-fired furnace option). The heated or cooled air circulates from the fan to the supply ducts, and openings in the home called supply registers. Return registers and ductwork return the air to the fan to be heated.
Some heat pumps are packaged systems. These usually have both coils and the fan outdoors. Heated or cooled air is delivered to the interior from ductwork that protrudes through a wall or roof. Another packaged system is the ductless room heat pump. These pumps will efficiently heat or cool a room or small house with an open floor plan. They are much more common for apartments and motel rooms than homes. They can be installed in a window or through a hole in the wall — wall installations being preferable for appearances sake. Through-the-wall installations, however, sometimes aren’t well insulated from inside to outside and can have infiltration problems. When used, mini-split systems can solve these problems.
Selecting a Heat Pump
When selecting an air-source heat pump, consider the following three characteristics carefully: the energy efficiency rating, sizing and the system’s components.
Energy Efficiency Rating
In the United States, a heat pump’s energy efficiency is rated by how many British thermal units (Btu) of heat it moves for each watt-hour of electrical energy it consumes.
Every residential heat pump sold in this country has an
Energy Guide Label, which features the heat pump’s heating and cooling efficiency performance rating, comparing it to other available makes and models.
The Heating Seasonal Performance Factor (HSPF) rates both the efficiency of the compressor and the electric resistance elements. The HSPF gives the number of Btu harvested per watt-hour used. The most efficient heat pumps have an HSPF of between 8 and 10.
The Seasonal Energy Efficiency Ratio (SEER) rates a heat pump’s cooling efficiency. In general, the higher the SEER, the higher the cost. However, the energy savings can return the higher initial investment several times during the heat pump’s life. Replacing a 1970s vintage, central heat pump (SEER = 6) with a new unit (SEER=12) will use half the energy to provide the same amount of cooling, cutting air-conditioning costs in half. The most efficient heat pumps have SEER of between 14 and 18.
You’ll find the Energy Star® label — sponsored by the U.S Department of Energy and the U.S.
Environmental Protection Agency — on heat pumps with an HSPF of at least 7 and a SEER of at least 12.
Many new heat pumps exceed these ratings, but looking for this label is a good way to start shopping for one.
Sizing
When selecting a new heat pump, it’s important that you determine the proper size needed for your home. Bigger is not better. Over sizing causes the heat pump to start and stop more frequently, which is less efficient and harder on the components than letting it run for longer cycles. A properly sized heat pump also will provide you with better comfort and humidity control than an oversized one.
The heating and cooling capacity of heat pumps is measured in Btu per hour. The cooling capacity is commonly expressed in “tons” of cooling capacity — each ton equaling 12,000 Btu per hour. Correct sizing procedures involve complex calculations, which are best performed by an experienced contractor, who uses sizing methods accepted by the heat pump industry. Don’t employ a contractor who guesses the size of the heat pump needed.
Rule-of-thumb sizing techniques are generally inaccurate, often resulting in higher than necessary purchase and annual energy costs.
System Components
You and your contractor should discuss options that will help improve your home’s comfort and the economy of your heat pump. Regarding ducts, for example, it’s important to carefully consider their design and materials, as well as the proper amount of space they require. Check your home’s blueprints to see if the architect and builder have planned adequate space for ducts and fans. Heating and cooling contractors complain that they often have to squeeze heating and cooling systems into spaces that are too small, resulting in constricted ducts and inadequate airflow.
Except for packaged systems, you’ll also need to select the proper type of indoor coil for adequate summer moisture removal.
Installing a New Heat Pump
A heat pump’s performance and energy efficiency not only depend on the selection and planning of the equipment but also on careful installation.
Consumers and home builders alike tend to accept the lowest bid for heating and air-conditioning work. This unfortunate choice can often leave a system lacking 10 to 30 percent in the materials and labor necessary to optimize heat pump performance. Rather than just accepting the lowest bid, it’s best to research the performance records of local contractors, and get involved in the planning and decision-making about your new heat pump system.
You can avoid most of the common comfort and performance problems from improper installation by following these guidelines:
♦ Make your home as energy-efficient as you can with proper insulation, energy-efficient windows and an effective air barrier. Then your contractor can install a smaller pump system with shorter duct lengths. In an energy-efficient home, it isn’t necessary to run ducts all the way out to exterior walls to install registers near the exterior walls.
♦ Install the ducts inside your home’s insulation and air barrier, if possible. Research shows that this strategy is a major energy saver.
♦ Insulate your ducts to R-8 if they must be located in an attic or crawl space beyond the home’s air barrier and insulation.
♦ Locate the outdoor unit on the north side of your home if possible. If not, pick a shady spot. There should be no obstructions within 10 feet of the sides with openings and the top.
♦ Specify that the measured air leakage through your new ducts be less than 10 percent of your system’s airflow. Air leakage of 5 percent or less is possible with careful workmanship.
♦ Tell your contractor that you want a return register in every room.
♦ Don’t use building cavities as ducts. Building-cavity return ducts are notoriously leaky and often cause comfort, energy and moisture problems.
♦ Pull on ductwork after installation to make sure it is fastened and sealed well. (Seal duct joints with mastic.)
Improving Performance
Poor installation, duct losses and inadequate maintenance are more of a problem for heat pumps than for combustion furnaces. A growing body of evidence suggests that most heat pumps have significant installation or service problems that reduce performance and efficiency.
According to a report on research funded by Energy Star®‚ more than 50 percent of all heat pumps have significant problems with low airflow, leaky ducts and incorrect refrigerant charge.
Increasing Airflow in Central Heat Pumps
The capacity and the efficiency of a heat pump depend upon adequate airflow. There should be about 400 to 500 cubic feet per minute (cfm) airflow for each ton of the heat pump’s air conditioning capacity. Efficiency and performance deteriorate if airflow is much less than 350 cfm per ton.
An ideal duct system has both a supply register and a return register for every room. Most homes, however, have only one or two return registers for the entire house. Air from other rooms must find its way back to these registers to be reheated or re-cooled. Obstructions in return air are a common air circulation problem, particularly from closed interior doors to rooms with no return-air register.
Blockage of supply or return air ducts and registers can pressurize or depressurize portions of the home, resulting in poor performance and increased air leakage through the building envelope. Restrictions to airflow have the greatest impact on the return-air side of the system, so repairs should start with the return ducts.
Air from every supply register must have an unobstructed pathway back to a return register. You can install louvered grilles through walls or doors, ducts between rooms and/or additional return ducts and registers to improve air circulation.
Technicians can increase the airflow by cleaning the evaporator coil, increasing fan speed, or enlarging the ducts — especially return ducts. Enlarging ducts may seem drastic but in some cases, might be the only remedy for poor comfort and high energy costs.
Air-sealing Ducts
Measurements of heat pump performance indicate that duct leakage wastes 10 to 30 percent of the heating and/or cooling energy in a typical home. It’s one of the most severe energy problems commonly found in homes because the leaking air is
20° to 70°F warmer than indoor air in winter and 15° to 30°F cooler in the summer.
Duct leakage may cause some minor comfort problems when ducts are located in conditioned areas. But when leaky ducts are located in an attic or crawl space, the energy loss is often large. Some of the worst duct leakage occurs at joints between the air handler and the main supply and return air ducts. Some main return ducts use plywood or fiberglass duct board boxes. These boxes frequently leak because their joints are exposed to the duct system’s highest air pressures. Heating and air-conditioning contractors often use wall, floor and ceiling cavities as return ducts. These building-cavity return ducts are often accidentally connected to an attic, crawl space, or even the outdoors, creating serious air leakage. Fiberglass ducts and flex ducts are often installed improperly. These ducts may also deteriorate with age, leading to significant supply-duct leakage.
The best heating and cooling contractors have equipment to test for duct leakage. Testing helps locate duct leaks and indicates how much duct sealing is necessary. Do not use duct tape for sealing — its life span is very short, often less than 6 months.
Adjusting Refrigerant Charge
Room heat pumps and packaged heat pumps are charged with refrigerant at the factory. They are seldom incorrectly charged. Split-system heat pumps, on the other hand, are charged in the field, which can sometimes result in either too much or too little refrigerant.
Split-system heat pumps that have the correct refrigerant charge and airflow usually perform very close to manufacturer’s listed SEER and HSPF. Too much or too little refrigerant, however, reduces heat pump performance and efficiency.
For satisfactory performance and efficiency, a split system heat pump should be within a few ounces of the correct charge, specified by the manufacturer.
When the charge is correct, specific refrigerant temperatures and pressures listed by the manufacturer will match temperatures and pressures measured by your service technician. Verify these measurements with the technician. If the manufacturer’s temperatures and pressures don’t match the measured ones, refrigerant should be added or withdrawn, according to standards specified by the EPA.
Refrigeration systems should be leak-checked at installation and during each service call. Manufacturers say that a technician must measure airflow prior to checking refrigerant charge because the refrigerant
measurements aren’t accurate unless airflow is correct.
Operating a Heat Pump
Like combustion heating systems, you control heat pumps using thermostats. If you leave and return at regular times everyday, you’ll save money by using automatic thermostats, which minimize energy use during the times the home is unoccupied. However, choosing an automatic thermostat’s reactivation time requires considering the duration of heat-pump operation necessary to restore a comfortable temperature. During the heating season, some homeowners also set their thermostats back 10°F, manually or automatically, when they leave home or go to bed.
A two-stage thermostat controls the heating. The first stage activates the refrigeration system. If it’s too cold outside for the refrigeration system to counteract the home’s heat loss, then the thermostat’s second stage activates the electric resistance coils. An outdoor thermostat will prevent the less efficient electric resistance heat from coming on until the outdoor temperature falls below 40°F. An outdoor thermostat also will prevent auxiliary heat from activating when an automatic thermostat is warming the house after a set-back period. Use setback thermostats that are only for heat pumps.
A defrost control tells the reversing valve when to send hot refrigerant outdoors to thaw the outdoor coil during the winter. During the 2-to-10-minute defrost cycle, auxiliary heat takes over, reducing the heat pump’s overall efficiency up to 10 percent. The two most common types of defrost controls are time-temperature and demand-defrost. Time-temperature defrost controls activate defrost at regular time intervals for set time periods, whether there is ice on the outdoor coil or not.
A demand-defrost control senses coil temperature or airflow through the coil and only activates defrost if it detects the presence of ice. Obviously, choosing a heat pump with demand-defrost will pay a significant efficiency dividend.
For greater efficiency, don’t locate a thermostat near a heat source or cold draft because they can cause a heat pump to operate erratically. This includes shading thermostats from direct sunlight. Also, do not turn the thermostat beyond the desired temperature. It will not make the heat pump heat or cool your home any faster. It will only waste energy. Residents who duel one another over the thermostat settings, moving it up and down to suit their different comfort levels, cause heat pumps to operate erratically and inefficiently.
Maintaining and Servicing
Heat pump performance will deteriorate without regular maintenance and service. The difference between the energy consumption of a well-maintained heat pump and a severely neglected one ranges from 10 to 25 percent.
Regular Maintenance
Either the homeowner or service technician can perform the following routine maintenance tasks:
♦ Clean or replace filters regularly (every 2 to 6 months, depending on operating time and amount of dust in the environment).
♦ Clean outdoor coils as often as necessary (when dirt is visible on the outside of the coil).
♦ Remove plant life and debris from around the outdoor unit.
♦ Clean evaporator coil and condensate pan every 2 to 4 years.
♦ Clean the blower’s fan blades.
♦ Clean supply and return registers and straighten their fins.
Professional Service
You should have a professional technician service your heat pump at least every year.
The technician can:
♦ Inspect ducts, filters, blower and indoor coil for dirt and other obstructions.
♦ Diagnose and seal duct leakage.
♦ Verify adequate airflow by measurement.
♦Verify correct refrigerant charge by measurement.
♦ Check for refrigerant leaks.
♦ Inspect electric terminals and if necessary, clean and tighten connections and apply non-conductive coating.
♦ Lubricate motors and inspect belts for tightness and wear.
♦Verify correct electric control, making sure that heating is locked out when the thermostat calls for cooling and vice versa.
♦Verify correct thermostat operation.
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Questions are often asked with regard to heat pumps and their requirement to defrost. This document attempts to answer some of the most common questions. Answers are deliberately non technical and do not cover specifics on any particular model, therefore some small allowances should be made for minor technical differences between units that can affect the way defrost is both initiated and then terminated.
What is the Defrost Function?
Defrost function is a feature on every heat pump and is designed to remove ice build up on the outdoor unit heat exchanger.
This has occurred during the heating process of the heat pump because the outdoor part has been taking the heat and moisture from the air.
How can I tell if my unit is defrosting?
Most units will indicate defrost by flashing LED’s on the front cover. This may be a red or green LED depending on the model.
Why does it need to happen?
If a heat exchanger is covered in ice the airflow is restricted and therefore the efficiency of the heat exchanger is greatly decreased. Ice on the heat exchanger also acts as a thermal insulation barrier preventing heat absorption. By defrosting the heat exchanger the efficiency is increased.
How often does it need to happen?
This really depends on the following factors.
• How cold / damp is the air around the outdoor unit
• How much work the unit is required to do, eg. room insulation or greater expectation to heat adjacent areas.
• Are there any mechanical defects with the unit.
Assuming for now there are no mechanical defects…how often would my unit be expected to defrost?
Most units will not check for a defrost requirement until at least 45 minutes have elapsed from initial start up. This period should have given enough time to bring the room to temperature.
After defrost has started… how long should it take to complete?
Defrosting function on most units is ended after a certain time has elapsed OR the outdoor unit heat exchanger temperature has risen sufficiently indicating that defrosting can be completed. Defrost termination can occur within 10 minutes.
If my unit is frequently defrosting... what could be wrong?
Regular and unsuccessful attempts to defrost an outdoor unit can be a sign that the system is undersized for the area to be heated, or that it may have a mechanical defect or is suffering from lack of maintenance. Refrigerant loss, coils blocked by dirt, restricted airflow due to obstruction such as foliage or blocked filters is all possible problems.
First try cleaning the air intake filters to the indoor unit as this may help to reduce the frequency of defrost and will help improve product performance. Also check your unit is not set to a fixed low speed as this will prevent the unit delivering full heat capacity while it can.
Adjust the fan setting to ‘auto fan’ as this allows the unit to automatically adjust the fan speed and so the output capacity will match the requirement. If the unit is the correct size the fan will slow as the temperature rises. Turn the heating on earlier in the day or leave it on in extreme cold conditions.
If none of this helps, we advise a visit by a heat pump specialist to help diagnose the problem.
If my unit is undersized, what can I do to remedy the problem?
The selection of any heat pump unit is the responsibility of the installation contractor. If an error has been made with the selection, your redress lies firmly with the contractor. Equipment is not at fault if it has been incorrectly sized for the application.
Is there anything I can do to decrease defrosting?
Your heat pump will need to defrost less and use less energy in a well insulated room. Keeping the doors and curtains closed will help. Insulate your floors and ceiling if they aren’t already.
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Heat Pump Noise
It is amazing how many problems faulty heating and cooling equipment can make especially if it makes a lot of different kinds of noises! Also amazing how many words people can use to describe them.
Below you can see a list of noises and sounds people usually use to describe a noise that is coming from their furnaces, heat pumps, air conditioners and boilers:
Back peddling, banging, booming, buzzing noise, chattering, chirping, clacking, clanging, clicking, droning, explosion, grating, grinding, groaning, grumbling sound, gurgling, hammering, high pitched, high pitched whine, high pitched whistle, hissing, howling, humming, knocking, metal hitting metal, moaning noise, out of balance washing machine, plane engine, popping, pulsating, random, ratcheting, rattling, roaring, rumbling, scraping, screech, screeching, siren, sputtering, squeaky, squealing, switching, swoosh, thumping, ticking, tinny, train like, vibration, weird, whining, whirring, whooshing, wobbling, woof noises or sounds.
Some people have a hard time to describe what kind of noise coming from their units, for example:
Furnace is making a loud noise, awful furnace motor noise, furnace noise reduction, gas furnace noise like a slamming door that vibrates, heat pump making funny noise, when I turn on furnace sound strange, our boiler makes noises through the whole house and so on!
If you one of them, please carefully read through all lists of noises and try to find one that describes yours.
Currently, on my site, I have six pages dedicated to these kinds of issues and they are all made the same way:
At the top of the module, you can see a short list of noises. If you click on any word from the list, which in your opinion better describes your type of noise, the page is going to jump down and you can read the question and the answer to that question or feedback written by a person who asked that question in the first place.
If you cannot find the type of noise, you are looking for or if there are several questions with the same type of noise just scroll down to the next module or go to the next page.
List of the pages:
Furnace/Air Handler Noise
Furnace/Air Handler Noise 2
Furnace/Air Handler Noise 3
Heat Pump Noise
Heat Pump Noise 2
Boiler Noise
Boiler Noise 2
Boiler Noise 3
Air Conditioner Noise
Almost all information that you are able to read on the pages above is taken from dozens of so-called forum websites. People were asking those questions, professional members were answering; people came back with additional information and so on. Sometimes all this process taking several pages, which in many cases was pretty much useless until the original poster gave up information how his case was resolved.
Therefore, if you would look at the pages above you are definitely will find an ultimate solution to the problem described in any given question!
Is it time to replace your heat pump? Fill out a Repair or Replace Report Card
List of Noises 1:
Whooshing sound 1
Tinny sound
Back peddling noise
Out of balanced washing machine noise
Buzzing noise 1
Metal hitting metal type sound
Vibration noise 1
Grinding noise
Buzzing Noise 2
Clicking Noise 1
Whining Noise 1
Heat pumps do tend to makes strange and/or loud noises at times, more so in the winter. Heat pumps have reversing valves that reverse the flow of refrigerant between the heating and cooling modes. During the winter, whenever the heat pump goes into the defrost mode, this valve shifts. Along with that is a "whooshing sound" which usually lasts for a couple of seconds. After that, the compressor sometimes sounds much louder than usual, almost a "tinny sound". After shutdown the Freon pressures equalize, during this period sometimes sounds are heard but this is normal
Another common loud sound is when the outdoor unit starts up or shuts off. Specifically, the newer "Scroll" type compressors. They make a "back peddling" type of noise on shutdown and on start-up they sometimes sound like an "out of balanced washing machine".
Sometimes customers complain of a buzzing noise from the outdoor unit when it's not even running. This is usually the reversing valve solenoid coil. It's low voltage (24 volts) so it isn't really wasting energy and sometimes they can be heard.
If you are hearing a very loud "metal hitting metal type sound", the fan blade could be hitting something: possibly ice, or a wire, or tubing. Take a look and shut the unit off immediately. This almost always ruins the fan blades and possibly the motor as well. If a piece of copper tubing shifted and is being hit by the blades, they could put a hole in it causing the Freon to leak out.
Then there is always the vibration noise, which sounds simple but can be the most difficult to eliminate. Sometimes it is just a matter of installing rubber isolation pads under the unit. Sometimes the refrigerant piping is strapped too tightly to the joists. Sometimes it is in the unit itself and cannot be eliminated.
Question
Grinding noise on startup
I have two AC units that grind on startup (one worse than the other) It only lasts for a second then stops. I had the HVAC guy here to check it out and he's stumped. Amp test proved normal. Things I can thing of are bent fins, bad blower motor (or low/no oil) and low amount of refrigerant although the air is cool as it blows into the home. Any other thoughts?
Answer
Refrigerant lines that rise to a vertical height of more than what is stated in the installation manual will cause this.
Compressor on ground and air handler in attic of two story house can exceed the limit.
Will sound like gravel churning for a few seconds.
They sell a kit I think to solve this, check valve or something?
This may also be a simple rain shield on the fan motor.
Refrigerant migration could be a factor.
Evaporator up, condenser down: If the refrigerant metering device is other than a TXV it may flood the compressor as it allows the liquid refrigerant to pass through the metering device rapidly until equalized. You guys hear this surging of refrigerant for a while after the unit shuts down from up in the house at the air handler? A TXV will "slam shut" when the compressor suction stops (most residential valves still have a small equalizing orifice inside the valve).
Creating a "Pump down" or just a "shut down" configuration by installing a solenoid valve in the liquid line will correct this. However, a hard start kit may be needed if the compressor doesn't have a start capacitor as the compressor must start against the head pressure of the refrigerant caused by the elevated AHU.
Excessive refrigerant charge (due to system design): The amount of refrigerant in a system must be kept to a minimum. Arbitrarily installing over sized lines may cause this. These flooding conditions are more prone in over sized refrigerant circuits.
No crankcase heater in a scroll compressor (or reciprocal compressor where slugging is occurring): Manufacturer thinks the scroll is tuff and doesn't need an accumulator, start capacitor or crank heater. Refrigerant has infinity for oil and during shut down it will migrate to the crankcase of the compressor. At start up the refrigerant (and the oil) are sucked up through the compressor. It makes one hell of a noise! Look for a compressor in a cooler location than the AHU (like the AHU in a 200 degree attic space).
Installing an accumulator in an AC that doesn't have one will help with a flooding situation.
The HVAC Tech should be able to identify this stuff.
Question
Goodman Condenser - Heat - Buzzing Noise every 60 seconds
I have a Goodman Condenser unit on my heat pump that’s about 5 years old. Recently I noticed an intermittent buzzing noise coming from my fuse panel and I was able to correlate it to my Heat pump turning on and running. When it first turns on for heating and thereafter at an interval of every 60 seconds it makes an electrical buzzing noise at the condenser unit, this causes a similar noise at my fuse panel. It sounds like an electrical short, but the breaker (40 Amp) never cuts off. I've turned the unit off since it's only used to heat the basement.
Answer
What would be causing this? It seems to be very specific to a 60 seconds timer in the condenser unit.
It could be your compressor trying to start but not being able to do so. It shouldn’t happen that often but in cold temp the overload protector may cycle that quickly. I recommend having it checked to salvage the expensive compressor.
Feedback
I had a service technician look at my unit and he diagnosed the problem as being the compressor. He checked the large capacitor and it was fine. The estimate for replacing the compressor is $1,200.00. For now I had him disconnect it so if I need I can run the Emergency heat. This is the unit for my basement area only; I have two other units that are Gas furnaces for my other floors of the house.
Question
Heat Pump Clicking Noise
Recently, my heat pump has started to make a clicking noise when it is turned off. The clicking is about one second apart and is continuous. I thought that it was one time occurrence, but when I checked after a day's time, it was still clicking. The thermostat is switched completely off. Thoughts?
Feedback
Well the problem ended up being the "Safe-T switch" which monitors the drainage reservoir to the outside. I bypassed the switch, and the AC turned on.
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List of Noises 2:
Clicking noise 2
Humming noise 1
Humming noise 2
Rumbling noise
Squealing noise
Whining noise 2
Clacking noise
Train like noise
Clicking noise 3
Hummimg noise 3
Whining noise 3 Jack hammer sound
Question
Clicking noise from solenoid
I just bought this house in August and it has what I believe to be a Carrier system (heat pump). House is all electric.
The system heats great but I noticed a periodic clicking noise that appears to be coming from a solenoid in the outside unit. It will click every half second or so for about 10 minutes and will stop when the thermostat shuts off the compressor. It doesn’t click all the time and for the most part, it seems to happen rarely (I've only heard it 2 or 3 times). Most of the time the unit is quiet (just the compressor and fan hum).
The vent temps are warm when the clicking occurs (no difference from when its not clicking).
I've never seen ice or frost on the outside coils as well. I am in central Arkansas.
Is this clicking normal? Like I said, I still get great heat out of it whether it’s clicking away or not.
Answer
What you are hearing is the reversing valve trying to go into defrost mode.
It could be the defrost board, the reversing valve, loose wiring from the thermostat to the heat pump, bad or weakly energized solenoid coil, or a combo of above.
Oh, wait, it also could be a defrost sensor going to the bad sending mixed signals to the defrost board, the thermostat, air handler control board.
You need to have this looked at so it doesn’t mess up anything that still is salvageable. Get a co. that your friends or good neighbors will recommend.
The defrost board is most likely the culprit. it has two relays on it that tells the heat pump (along with the other electronics) what to do among them is to tell the heat pump to go into defrost mode, it works like this, in very simple terms.
The sensor (on the heat pump coil) or a timer built electronically on the board sends a signal to the blower on the heat pump to cut off and to reverse the valve on the heat pump, basically putting it into a/c mode, also it tells the air handler to turn on the aux/emergency heat strips so you won't lose your comfort level in the home. After everybody is satisfied (timer or sensor) it goes back into normal heat mode, reverse valve, blower comes back on, heat strips cut-off, everything back to normal. By the way, at times when it is in defrost mode, you may see something that looks like smoke rising out of the top of the heat pump while it sits there and hums, this is normal. What’s happening is the heat from the compressor and coils create steam.
I don't know what you would have to pay for a new board, you not being certified, but they run from $28.00 to a couple hundred bucks for contractors.
Your carrier should be around 35.00-50.00 if you can find a Ferguson’s or a cc Dickson’s.
Question
AC Unit not working. Fan out, compressor making a humming noise.
So do you guys have any other ideas of what can be causing this issue?
- Furnace fan blowing when AC on
- From the AC Unit outside you can hear a hum coming out of the compressor and you can hear a click coming out of it once in awhile
- The Fan of the AC Unit is not moving at all
Is there any possibility that this could be a motor problem?
The compressor seems to be working but cold air is not moving due to the fan not working.
Answer
Okay the humming you are hearing is the compressor trying to start. You can get fan motor to start with a screwdriver. All points lead to bad dual capacitor. You most likely have one capacitor that controls both compressor and fan. If its bad, compressor will hum until it goes out on internal overload, fan would not start unless you give it a push by hand.. I really think you need to get a new capacitor first, they are cheap and easy to replace, and I’m really betting this will cure your problem.
Question
Heat Pump Air Handler noise
What might cause a humming noise, similar to the hum you hear near an electric transformer box, coming from an idle heat pump's air handler? The thermostat was set to cool, auto and was not calling for cooling. I had lowered the t-stat and the A/C operated for a few minutes, raised the t-stat to stop the A/C. About 15 minutes later the humming noise continued. It is a 1987 York air handler. The condenser plate is not readable so it's probably the same age.
Answer
Nothing is wrong when you get humming from a transformer unless it is unusually loud.
They all hum. Now if it changes to a hum to a rattle, then change the transformer.
Sometimes the noise is not the transformer but the mounting is loose and just amplifies the noise. Sometimes they get louder just before burning out... but not always.
Just like people, some are quiet and some are loud but that says nothing about how well they work
Question
I just had a New Lennox XP19-036 two speed heat pump installed with new Lennox oil furnace. Heat pump makes loud rumbling noise after on for 5 min and a loud tone is heard which I located at furnace plenum - what’s happening here?
Answer
It is hard to say without hearing the noise. The most common noise problems I run into on new heat pumps are overcharged. The installers may not have adjusted the refrigerant correctly and if there is too much you will defiantly get a noise. This noise could be a pulsation or high pressure sound. I would call them back to recheck the unit.
Question
Our outside unit just started to make a loud squealing noise. It is a 2 ton unit, it continues to make heat but makes the loud noise. The unit is approximately 7 or 8 years old.
Answer
It's more than likely the outdoor fan motor failing, turning it off was the right thing to do, if this is a heat pump and you have an emergency heat switch on the thermostat you can have her turn it to that and you will get electrical heat strip until you can get the unit repaired.
Question
Whining noise from heat pump in Aux mode
I have a 1 year old Carrier heat pump mounted in the attic for the top floor of my house. Whenever Aux mode kicks in, I hear a high-pitched whine, kind of like a muted dentist drill. When it exits Aux mode, I hear a whooshing noise, like from a pressure relief valve. After that everything sounds normal. The whine appears to be coming from the condenser outside and the whooshing noise sounds like it's coming from the attic. Other than the noise, everything appears to run normally.
Any ideas as to what to look for? I had a heat pump in a previous house and it was never this loud.
Answer
The whooshing I’d say is when the 4way valve opens and lets the Freon like turn around in the pipe from heat to cool. I wonder if you could be a little low on Freon. Is the big pipe hot when the pump is running? If so it should be Ok.
The whine outside is the condenser fan.
Question
Carrier Heat Pump unit is making a clack out noise outside and a whistle inside?
Recently my carrier heat pump has been making a strange clacking noise at the outside unit. I did notice that my drain line at the coils inside was a bit clogged so I cleared it. I am not sure if it's popping up again right now. It's also making a very slight whistling/whining noise at the inside unit that it hasn't made before. That is continuous whenever the unit is on. The clacking noise is intermittent and appears to be the worst when the unit is shutting off or even after it is off it will clack for a minute or so.
Has anyone else run into this? Is this a sign of some maintenance I need to do? I've had this thing checked out before and it's less than five years old but it is an el cheapo carrier heat pump installed by the home builder.
Answer
When you have a heat pump that means that the whistling noise is coming from the reversing valve and the clacking noise is the reversing valve relay, unless you got a check valve that may be going bad. Anyways, if everything is working good, then leave it the way it is. What you want to do is cut the power off and start tightening all the electrical connections. If you see any of the connector's insulation kind a burned out, then is time to replace that connector. Check the contactor as well; make a visual inspection to see if your contacts are not worn out. Check all connections coming from the t-stat wire to the unit. If you see any wire nuts, then remove the wire nuts and peel new wire and put a new wire nut on it. If is making false contact that means that is turning on and off the reversing valve continuously, and that could be the problem too. Then put the cover on again and put the power back on. If that didn't do it, may be your reversing valve may be going bad.
Question
Heat pump making loud noise at times, inside breaker keeps cutting off?
At first it was just an occasional noise at night when it is cold.
Then the breaker started to cut off after the unit was on for a short time.
If I flip the breaker back on, the outside unit comes on, and makes the loud noise at start up.....but then after a short time, the breaker shuts off, and everything quits again, what is wrong?
The fan works, the unit does deliver warm air when it is on.....the loud noise sounds like a train coming through my yard.
Answer
This sounds like the compressor unit or even the fan motor is going bad, but nonetheless call a heating service man and has it checked. The breaker is tripping because something is overloading or it has a short or something in the unit itself.
If you want to keep heat you should call them out as soon as you can.
Question
Had an Amanda 3 ton communicating heat pump installed last year. 16 seer this unit has performed perfectly but it's too loud. Had company out numerous of times and can't seem to find a solution to how to make it more tolerable. Company has been very good about it. But, we are coming up to our 1 YEAR 100% satisfaction replacement guarantee. Like I said. The efficiency has been great but would hate converting back to just to furnace/AC unit. Any suggestions to what to look for would be appreciated. Maybe a different brand name is more quiet?
Units installed is Amana AMVC95 and ASZC16-HP with communicating t-stat. Sounds we're hearing is from outside unit. Jack hammer sound, whooshing sound along with moose call that last 30 to 45 sec. Unit is installed on north side of house where there are no windows. House is brick and can hear it from both bedrooms inside. 410 refrigerant is being used. Installer is thinking a R22 unit would be less noisy. I thought R22 units were phased out?
Answer
Within the last year Amana has come up with a "quiet defrost" feature. Contact your dealer or Amana customer service and see if this feature can be added to your unit. It shuts down the compressor for a short time and lets the Freon equalize to eliminate the "whoosh" sound at defrost. I imagine the "clattering" sound is also part of the reversing valve/defrost noise. Also make sure your installer has the defrost interval set properly. In our area, we use the 90 minute setting. Otherwise the outside unit is going to check for defrost too often. The only R-22 units available are 13 SEER, so you'll lose a lot if efficiency and warranty coverage (and I'd worry about this installer's recommendation too, as it does not make much sense). Call the Amana customer service line to get another opinion before you change much of anything. You've bought their premium equipment, so take some time to check things out before giving it up. Oh yeah, make sure your Freon lines are not strapped tightly to your floor joists as this will transmit compressor noise throughout your home.
Follow-up
Had installer out this morning. Our system does have the option of setting the defrost cycle and compressor delay at the T-stat. Upon checking the settings, our compressor delay was set at ZERO 0. Defrost cycle was set at 30. Compressor delay is now set at 30 and defrost cycle is set at 90.
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List of Noises 3:
Knocking noise 1
Whooshing noise 2
Buzzing noise3
Hammering noise
Vibration noise 2
Gurgling noise
Screeching noise
Noise comparison
Buzzing noise 4
Knocking noise 2
Noise and vibration 3
Question
I bought my train duel fuel heat pump last year and the fan is making a knocking noise and not spinning. Is this a normal thing or not? I called the company that installed it and they came out last week and told me everything was fine, but it sounds terrible so I just wanted to know if I should be concerned.
Answer
I think you may be hearing the defrost on the heat pump kick in I will explain it and see if it sounds like what it is doing. A heat pump uses the outdoor air to produce heat for inside so when it gets close to freezing or below the copper starts to frost because of the extreme heat difference in the air and what is in the lines so it goes into what is called a defrost cycle. There is a small sensor in the unit that senses the frost starting to build up so it shuts down the fan and the compressor. The heat pump goes into a defrost cycle it sounds like a fridge humming x1000. This heat the lines to thaw them and when the sensor feels it is good it turn the fan back on and the unit continues heating. When the fan starts back up steam will sometimes roll out of the unit and it makes a gushing sound like a train starting up to roll down the tracks. Now you have duel fuel so there should be an outdoor sensor that is set to around 40 degrees or so that tells the thermostat to shut off the heat pump heat and turn on the gas furnace heat while it is this cold outside.
Question
I moved into my house in June 2005. It has a 2 1/2 ton Philco split system heat pump that was manufactured in February 2000.
Every so often I can hear a strange whooshing noise from the outside unit when standing in the kitchen. It's not extremely loud or high pitched, more like the sound of an air brake releasing. It only lasts a few seconds then repeats a minute or two later. After that, it may not repeat for a few hours.
This is my first house with a heat pump and I am totally clueless. The house was inspected before purchase, but because the outside temperature was above 60 degrees, the inspector could not test the heating. According to the inspection report, the only part of the combined system not tested was the reversing valve.
Answer
What you are hearing is the unit is going into defrost.
When a heat pump is in the heating mode it actually cools the outside air. To do this the outside coil gets colder than outside temp causing the moisture in the outside air to freeze on the coil. when the coil temp drops low enough it has to defrost the ice build up so it switches to the cooling mode (outside coil gets warm) to melt the ice. The outside fan also stops (to help speed the process up) and the Aux heat comes on (to compensate for the cooling).
No worries at all.
I wouldn't even bother calling a service tech unless it is not heating like it is supposed to. If you do, I bet they tell you it is fine.
Question
Heat Pump Problem
Last night I noticed the outside condenser unit for my heat pump was making a loud buzzing noise. I went out to look at it and saw that the fan was not running. The Freon supply and return lines were both warm. I went into the house and turned off the heat at the thermostat. The air handler kept running, blowing semi warm air, and the condenser started steaming??? The only way I could get the air handler to stop circulating was to flip the breakers. The temp last night was about 25 degrees.
When I got up this morning, I fired everything up and it all worked fine.
Does anyone have any idea what the heck happened? Is there any fire hazard?
Any info you can give me is appreciated. I'm going to call a pro to look at it, but I always like to have an idea of what's going on ahead of time.
Answer
A heat pump will defrost in heating mode and when it happens the outdoor fan will cut off, the Freon will reverse which can make an odd sound, and steam/water will come from the unit. If there is something wrong with the unit the fan will never come back on. I would turn it back on and give it a few min. and see what happens. Also the indoor fan was running because the t-stat was still calling for heat and this is what controls the units. So by turning off the outdoor unit would not have turned the indoor unit off. Think your unit is in normal operation.
Question
Loud hammering when ac compressor shuts down
I am a general contractor (jack of all trades … master of none). Anyhow, I live in So Cal, unit is 30 yr old General Electric with 10 yr old rebuilt compressor. Inside is a Carrier furnace with who knows what evaporator coils. Cools great but hammers like crazy the hotter the outside temp. The best description of the noise is that it sounds similar to water hammer noise in plumbing. Hammering lasts 5 to 20 seconds after compressor shut off. Have grabbed the copper lines on both the compressor & evaporator ends and cannot tell what is happening. This is obviously a pressure equalization or bleed back from a high pressure to low pressure side. I’m going to guess a bad expansion valve? Any other ideas?
Answer
It is possible if it gets noisier as it gets hotter outside that the condenser coil is dirty or there is a problem with the fan.
To get some idea if this is so you could feel the smaller of the two lines going to the indoor coil.
The smaller line should be in a range of about 100* F. This would feel like the surrounding temp. If hotter you may have a problem.
Could also be several other things.
You might need to call a tech to install a set of gauges to diagnose it for you.
Feedback
Anyhow, somewhere in the posts, I read that my line temps didn’t seem right. So, I removed the can surrounding coils of the outside unit – compressor. I had previously replaced the fan motor and the inside of the coils were very clean. Upon removing the can, I immediately saw the problem. The entire outside of the coils were coated in a 30 yr mixture of fine sand, adobe dust, etc which had solidified into a layer of adobe … it looked like someone had applied a layer of stucco to the coils. A line pressure hose removed about 95%, I then sprayed it with a degreaser, and then gently power washed the coils (a previous post warned of possible damage to “feathered coils”, but nothing blew off. Someone might ask “why did you not notice this earlier?” The can on this compressor is louvered and you cannot see the outside of the coils without disassembling the can. From inside the can when replacing the fan motor everything was so clean, I just did not look further … my mistake.
The unit runs so well now that it almost puts frost on the interior walls and runs about half the time.
Question
Heat Pump vibrating noise
Have a 4T Carrier HP and it has been doing a great job keeping us warm in KC. However, I am getting a "droning noise" that goes thru the house every once in a while, and it gets worse the colder it gets. HVAC guy said that the line set was clamped to the joists, which is why I am getting a vibration noise. Does this sound correct, and what can I do to fix it? I'm thinking I should set my emergency heat to 35 or 40 and use the furnace at the lower temps.... Thanks.
Feedback
Ok guys, finally got the vibration absorbers installed on my Freon lines today. Unfortunately not very cold here tonight so the unit's not running a lot. If you'll remember before I said there was a very loud hum and vibration noise coming from a 4 ton hp. So today my contractor comes out and installs 2 vibration absorbers on my Freon lines. (2 different sizes) one is made by Mars (motors and armatures inc.) the other is made by a company called "Packless" (see their website http://www.packless.com/splash.html. Once you get to the homepage, click on the logo, then on vibration absorbers for more details). Anyway they have been installed and I can honestly say I notice a difference. Is the hum completely gone? Well the answer to that is not completely downstairs in the den, but it does seem to be much better. In fact with the television on it is hardly noticeable. And my wife says I'm being Anal about it saying she can't hear anything but the unit (which again, is located on the other side of the wall) running. It is slight so she may be right, and of course that's a good thing. I can tell you there is a world of difference upstairs in the spare bedroom and adjoining bathroom. Hardly noticeable at all. In addition to installing the vibration absorbers my contractor also ran a metal rod down into the ground and then tied the Freon lines to the rod to help divert vibration away from the house and down into the soil. So the big question is did this help? The answer is very much so...and if my wife is right, and all I'm now hearing in the den is the hp unit itself running, then it worked 100 %. But even in the worse case, it has helped tremendously.
Question
Heat pump liquid line gurgling
Is it normal for the liquid line in a heat pump system to gurgle near the interior coil when the HP is in defrost or cooling mode?
The noise is audible from 3' away when the HP is cooling in marginal air conditioning weather. When the HP is defrosting in 25 degree weather, the noise is loud enough to be audible in adjoining rooms, through 8' of distance and a sheetrock wall.
If these details are significant, it's an R-410A system with a TXV on the interior coil.
Answer
I suspect liquid is flashing, which would indicate low on charge, also could be non-condensable in the system.
Gurgling sounds at TEV: Low evaporator heat-loads lead to reduced liquid line mass and increased evaporator mass could be due to airflow problems. Eliminate low evaporator heat-loads before looking into adjusting the refrigerant charge. Gurgling - pulsation noises in Liquid Line at the expansion device can be caused by low evaporator circuit heat-loads, low charge, and/or non-condensables and moisture in the system. Unbalanced airflow through the various distributor circuits of the evaporator coil will cause the TEV to close down refrigerant flow starving the coil. Piston-flow-rators will make it impossible to properly charge the system and cooling will be greatly compromised unless you eliminate the cause!
On every Rheem condenser cover it lists "non-condensables and or moisture" as causes for a gurgling or pulsating noise at the expansion device. The entire evaporator circuits, may not become active for various reasons, - "the entire coil must become fully active for efficient performance."
Question
I have a Bryant model 597CNO36-D compressor outside that is regularly tripping the house panel breaker and then after the breaker is reset, it will run, but periodically make a loud screeching noise. I believe it is the fan making the noise, but I am not certain. I have shot the following 37 second video that documents the noise (watch eleventh video)
I'm wondering about the condenser being hot to the touch. Is that normal? Should it be cool? I don't want to invest a replacement fan motor if the condenser is dead.
I have found a replacement fan motor online for $213, but I don't want to swap out the motor if the condenser itself is the culprit tripping the breaker and I'll have to replace the whole unit anyway.
The unit is ten years old and it seems like the thing has to run all the time to keep the house at 75-76 degrees.
Answer
Sounds like the motor. Keep looking for motors. You should be able to find one a bit lower priced.
If the fan is spinning slower then normal the condenser will be hot to the touch.
If your touching it where the motor mounts, it will be hot.
Question
Noise comparison, Trane XL20i, Carrier Infinity 21, Lennox XC21
Any direct experience with how these three outdoor units compare in terms of noise level?
From the online brochures, it looks like the XL20i may be the noisier of the three (but still referred to as being quiet), with the Carrier and Lennox being about the same. But maybe in real life there isn't much difference? I'm looking most likely at a 3-ton system.
I guess when operating at full capacity, the ranking could possibly be different than when running at the lower rate. Thanks !
Answer
Lennox XC21 is the quietest
Infinity 21 is in the middle
Trane XL20i is the loudest
The Trane XL20i is almost twice as loud and the Infinity 21 right in the middle.
All three units are virtually silent from 15ft and you can easily carry on a conversation next to any of them without raising your voice.
Structureborne Sound. pdf file
Refrigerant Piping Manual for Small Split Cooling and Heat Pump Systems. pdf file
צמצום רעש משאבת חום
Is it time to replace your heat pump? Fill out a Repair or Replace Report Card
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List of YouTube Videos
01. Carrier Heat Pump Noise Problem
02. Heat Pump Defrost
03. Heat Pump Headaches
04. More Noisy Goodman Heat Pumps
05. Noisy, Loud, Squeaky, Heat Pump / Air Conditioner Trane XR1
06. Condenser Unit Fan Noise-Solved by Replacing Fan Blade
07. How Noisy is Air Source Heat Pump
08. Strange Heat Pump Ticking
09. Trane XE 1000 XE1000 High Pitched Noise or Whine
10. Heat Pump Problem
11. Squealing Bryant Aero Cool AC Condenser Fan |
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