How to Troubleshoot a Heat Pump

In cold weather, the heat pump extracts heat from the cold air outside and releases it inside the house. The process is reversed for cooling during warm weather.
©2006 Publications International, Ltd.

A heat pump not only heats your home during the winter, it also cools it during the summer. It does not burn fuel to produce heat nor does the electricity it consumes go through an element. The heat pump functions on the same principle as refrigerators and air conditioners: A liquid absorbs heat as it turns into a gas and releases heat as it returns to a liquid state.

During the summer, the heat pump operates as a standard central air conditioner: It removes heat from the house and vents it to the outside. A liquid refrigerant is pumped through an evaporator coil of tubing. The liquid expands as it moves through the coil, changing to its gaseous state as it absorbs heat from the air surrounding the coil.


A blower then pushes air around the cooled coil through ducts and into the house. The gas, now carrying considerable heat, moves through a compressor and begins the liquefying process. It then moves to a condensor coil outside the house, where the compressed gas releases its heat and returns to a liquid state.

During the winter, the heat pump reverses this process, extracting heat from the cold air outside and releasing it inside the house. The heat pump is very efficient when the outside temperature is around 45 degrees Fahrenheit to 50 degrees Fahrenheit, but it becomes less efficient as the temperature drops. When the outside air temperature is very low, an auxilery electric heater must be used to supplement the heat pump's output.

Like standard electric heating systems, this auxilery unit is more expensive to operate. Thus, in areas where the winter temperature is below freezing, a heat pump is not practical. It has few advantages over conventional heating systems in areas where air conditioning is not necessary, but it is very efficient in warm to hot climates.

Heat pump maintenance is important. Small problems that are not addressed early can lead to very expensive compressor problems later. And since maintaining a heat pump is more technical than caring for the average heating system, you should call a professional service person when the pump malfunctions. You can, however, keep the system free of dirt by keeping the filter clean and by removing any other obstacles to the flow of air.

Proper outdoor maintenance of a heat pump is also important. Learn how to perform this type of maintenance in the next section.


Outdoor Maintenance for a Heat Pump

It's important to replace the filters and clean and lubricate the components of a heat pump on a regular basis. But heat pumps, like central air conditioners, have an outdoor unit that contains a compressor, a coil, a fan, and other components. To function properly, this unit should be kept free of debris such as leaves and dirt. The unit should be level on its concrete support pad.

Clean pine needles, leaves, and dirt out of updraft fans by removing the grille, which is held to the frame by a series of retaining screws. Make sure the power to the unit is off before tackling this type of cleaning. A vacuum cleaner hose can sometimes be inserted between the fan blades to remove debris from the sides and bottom of the unit.


At the beginning of each heating season, set a carpenters' level across the top of the metal cabinet and check the level from side to side and from front to back. If the unit is no longer level on the pad, lift the pad back to level by prying it up with a pry bar or a piece of 2-by-4. Build up the ground under it with stone or crushed rock. Also check the piping insulation for deterioration. If this insulation is faulty, replace it with new insulation, available at heating supply stores. Installation instructions are usually provided by the manufacturer.

A power interruption is an obvious cause for concern, but you can handle this situation by following the guidelines mentioned in the next section.


Heat Pump Power Interruptions

If a heat pump has been off for more than an hour because of a blown fuse, a tripped circuit breaker, or a utility power failure, the unit should not be operated for about six to eight hours, especially if the temperature is 50 degrees Fahrenheit or lower.

The lubricant in the pump's oil reservoir may be too cool to circulate properly and may cause damage to the valves of the unit. Instead, set the pump on emergency heat. This turns the pump off and keeps it from running.


Leave the pump in this mode for about six to eight hours, then switch the pump to its normal heating setting. If little or no heat is generated at this point, call a professional service person for repairs.

Whatever problem arises with your heat pump at whatever time of the year, you can find solutions in this article.

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