Lennox Defrost Mode

[Berniece Domnick]

Heatpumps typically freeze in cold weather, particularly if the area where you live has high humidity. This can occur even if the outdoor temperature is above freezing. Because the outdoor coil on your heat pump is typically 10 to 20 degrees colder than the outdoor air, if it is a 39 degree day the outdoor coil may be as cold as 24 degrees. If on that same day the dew point is as high as 33 degrees then moisture will have no option but to condense on the surface of the coil. Since it freezes at 32 and the coil is at 24, the moisture turns immediately into frost.

The worst case scenario for a heat pump however, is when there is snow falling. First, the conditions are already perfect for moisture to freeze on contact on the outdoor coil. Second, as the outdoor fan motor pulls air across the outdoor coil, those beautiful white snowflakes that are floating towards the ground get drawn into the coil. In this case, the system may finish a defrost cycle and within just a few minutes have pulled enough snow in the coil to require another defrost cycle.

If there is any form of frozen precipitation falling (snow, freezing rain, sleet), change the mode on your thermostat to E-heat. Also, If the weather forecast is calling for a hard freeze warning and you see frost on your unit for more than 1 hour, then use E-heat. Once the weather conditions have improved, if you still have concerns about the frost on your unit, give a call to a service provider to insure your unit is working properly.

Investing in a regular HVAC maintenance plan is also a good way to prevent against freeze up issues. Your technician can help you anticipate the freezing conditions that lead to freeze ups, and keep your system running smoothly year round.

One thing you could try to do to unfreeze your heat pump (if your system is equipped with it), is simply turning on the fan. Blowing air will usually thaw the equipment within 60 minutes. If the outdoor temperature is particularly low, you can set up the fan on an exhaust setting. Running the fan for a while might not solve all problems and freezing issues, but it is a short term solution you can try. Not all systems have a fan setting however. For example, the Bryant heat pumps we install do not have this option, but some other systems do.

If your heat pump has frozen up for whatever reason, give it at least 4 hours to defrost itself. For freeze ups lasting longer than 4 hours, call in a service technician to take a look or follow the alternative suggestions listed above. However, If you have any doubts about troubleshooting your system on your own, we suggest you schedule a maintenance call. We primarily install and work on Bryant heat pumps and are also a Bryant dealer, but we can service many other heat pump brands as well. We look forward to assisting you!

It is essential to understand that, for both heating and cooling, heat pumps transfer heat from one area to another. It draws heat energy from the outside air throughout colder months and moves it inside to heat your home. And to cool you off in the summer, the heat pump takes heat energy from inside your home and releases it outside.

Like auxiliary heat, emergency heat is a setting that activates the electric resistance heating strips to warm your home. However, while the auxiliary heat automatically aids the heat pump system in reaching the set temperature, the homeowner's emergency heat is turned on manually to be your primary heat source when your heat pump system malfunctions. As a result, the emergency heat mode is a significantly less efficient way of heating your home, so it should only be used when absolutely necessary.

You should turn the Emergency Heat mode on when your thermostat does not reach its desired temperature for a substantial amount of time. In this event. it is likely that your heat pump system has malfunctioned. If the heat pump system is unable to warm your home and the auxiliary heat will not satisfy the thermostat, then it is time to utilize the emergency heat mode. As soon as you turn on the emergency heat, call an HVAC professional for a heat pump repair. Otherwise, the emergency heat will run up your utility bill fast!

Homeowners should expect auxiliary heat to turn on during colder temperatures, especially under 40 degrees. Your heat pump is an amazing appliance that can efficiently extract warmth from the outdoor air and transform it into cozy comfort inside your home. However, at temperatures at or below 40 degrees, heat pumps lose quite a bit of efficiency, which can cause problems for maintaining optimal indoor conditions. This is because the heat pump cannot withdraw enough heat from the outside air fast enough to warm your home.

The auxiliary heat assists the heat pump in achieving the thermostat's set temperature. Once the set temperature is met, the heat pump and the auxiliary heat both shut off. If your Auxiliary heat is running for an extended time, you should call for a heating repair.

Homeowners should anticipate the auxiliary heat coming on when they raise the thermostat's set temperature by three degrees or more. Your heating system needs to operate with auxiliary heat to keep up with the household's new needs.

It is normal for your heat pump to accumulate some ice during colder months. However, too much ice greatly inhibits its heating and cooling capability. Therefore, your heat pump is equipped with a defrost control board that monitors defrost cycles and ice formation on the outdoor condensing unit. If the defrost control board senses the heat pump condensing unit has been too cold for too long, it signals the reversing valve to send hot refrigerant outdoors to thaw the outdoor coil. When defrost mode is activated, your heating system relies on the backup heat (aux heat) to keep your home warm. Therefore, if the heat pump is in defrost mode, you will also need to make good use of your auxiliary heat.

The auxiliary heat should only run for as long as it usually takes for your home to meet the temperature set on the thermostat. If the auxiliary heat runs either every time you turn your system on, an unusual amount of time (such as longer than 30 minutes or all day), or does not turn off, you should have your system evaluated by an HVAC pro. The auxiliary heat is an aid to your house's heat pump system, so while it is customary for it to turn on during cold weather, the homeowner should take note if it is operating for a prolonged period.

If your auxiliary heat operates for an unusually long time, you have a problem with your heat pump. It has turned on because your thermostat is struggling to reach and maintain its set indoor temperature. So, when auxiliary heat stays on, you can be certain the heat pump is malfunctioning. Read on to understand the most common reasons your auxiliary heat won't turn off.

The fan motor circulates air across the the outdoor condenser coil. Without critical airflow from the condenser fan, the heat pump will have difficulty absorbing enough heat (or releasing heat in the summer) to meet the thermostat's demands. Whether your fan motor is broken, dirty, or covered in ice, your heat pump will struggle to provide heating if proper airflow is prevented or inhibited. Therefore, if you have a faulty condenser fan motor, your auxiliary heat will be working hard this winter to keep you warm.

Refrigerant is a substance that changes states from gas to liquid. The ability to alternate between gas and liquid makes it possible to transfer heat between the outdoor coil in the condensing unit and the indoor coil in the air handler. Low refrigerant is due to a leak and means low heat absorption, causing many problems down the line, such as insufficient heating or cooling. If your heat pump system is leaking refrigerant, you are sure to face problems. As a result, your heat pump will struggle to absorb heat, thus relying on auxiliary heat.

If your heat pump is over 10 years old, it most likely uses Freon R-22. Freon-22 is a type of refrigerant has been phased out due to EPA guidelines. Check out our blog about the R-22 Freon ban to learn how it may affect you.

The compressor is part of the outdoor condensing unit. The compressor, which is powered by electricity, turns the refrigerant from a gas to a high-pressure liquid and pushes it through the outdoor condenser into the indoor air handler. If your AC compressor won't turn on, the heat pump system's ability to transfer heat will cease. Therefore the auxiliary heat will continue to run with no support from the heat pump system.

Your heating system depends on the backup heat (aux heat) during defrost mode to keep your home warm. So, if the defrost control board malfunctions, the aux heat will run extensively. Furthermore, if the defrost control board fails to defrost the accumulation of ice on your condenser, critical heat transfer will get restricted. As a result, your heat pump system will be unable to meet the thermostat's demands, resulting in the Auxiliary heat kicking in.

Every heat pump system has a reversing valve. The purpose of the reversing valve is to change the direction of the refrigerant. This is what makes the heat pump functional for both heating and cooling. However, if the reversing valve is faulty, your heat pump system may operate in cooling mode when the thermostat calls for heat. When this happens, the heat pump system pushes out cold air from your vents, while the auxiliary heat keeps trying to raise the indoor temperature. As a result, the heating and cooling functions of your heat pump are competing against each other, which will make your utility bills skyrocket!

It is nearly impossible to fully prevent the auxiliary heat from coming on when you are located in the North East United States. The heat pump system is very efficient, especially when the temperatures are above 40 degrees. However, when the temperature dips below 40 degrees, your heat pump may struggle to withdraw enough heat from the outdoor air to properly warm your home. The auxiliary heat is an essential function for maintaining optimal home comfort.

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