Heat Pump ProblemsHeat Pumps are very popular especially in the South where air source heat pumps are mostly favored over straight air conditioners with a gas furnace for heating. With a heat pump one system can do it all especially in the mild winters of the South. In the North some people rely on a geothermal heat pump system or a water source heat pump where the heat is extracted from the ground instead of the air like an air source heat pump works. While air source heat pumps are cheaper to install the geothermal heat pump systems will save a lot of money over the life of the heat pump in operating costs so as far as efficiency is concerned the geothermal heat pump rules the day. There may be a time when your heat pump will begin giving you problems so we decided to post an article to help some people diagnose the heat pump problem in an effort to better understand the system. Some minor repairs can be done by someone with advanced do it yourself skills however we always recommend you call an HVAC contractor to repair the problem if you have a problem with your heat pump. Before you get started you may want to take a look at the articles, “How Heat Pumps Work” , “Heat Pump Components” and “heat pump sequence of operation“. To solve heat pump problems you at least need to be familiar with a heat pump and the heat pump components so those two pages will help you.
Heat Pump Problems - AccumulatorOne of the most problematic heat pump components that I often find wrong is the accumulator. An accumulator is a reservoir that allows liquid refrigerant to be stored and boiled off so it does not harm the compressor when it is operating in cold ambient conditions. It protects the compressor in the winter and is an essential component to prevent other problems with the compressor. The problem with all the accumulators I have seen is they are made out of steel and the accumulators that are exposed to the environment usually rust despite the best efforts of the manufacturer to paint and protect the accumulator from rusting. Most accumulators will rust out on the bottom and the heat problem problem will start with a pin hole leak allowing refrigerant to leak out and eventually the heat pump stops working until refrigerant is added to the unit. The accumulator needs to be changed to eliminate the problem leak. This heat pump problem should be done by a qualified HVAC technician.
Heat Pump Problems - DefrostThe next heat pump problem on the list is the heat pump defrost board. The defrost board controls the defrost in the colder months when the heat pump condenser is operating below the dew point and collecting frost and ice on the heat pump condenser coils. The ice and frost on the heat pump condenser coils needs to be removed so the heat pump is equipped with a defrost cycle that will change the unit over to the cooling cycle causing the condenser coils to heat up and melt the ice. At the same time the defrost control board activates the heat strips or back-up heat inside the home so the occupants do not know the heat pump is on in the cooling mode. For whatever reason, perhaps they get wet or some electronic component on the board goes bad but defrost control boards will go bad from time to time and need to be replaced to eliminate the heat pump problem. Of course the best replacement in many cases for a bad part is a direct replacement so for the heat problem to be fixed you need to get a new defrost control board from the manufacturer. It is best to get an HVAC tech to take care of the problem as the defrost control boards are usually located inside a cabinet with high voltage so there is a danger involved in changing a defrost control board.
Heat Pump Problems - Reversing ValveSpecific to heat pumps the next problem one can encounter is the reversing valve. The reversing valve will shift from cooling to heating mode and back again depending on the setting on the heat pump thermostat. Sometimes the reversing valve can get stuck and require a slight tap with a wrench. If the wrench does not do the trick then other measures must be taken including possibly changing the reversing valve. Other problems that can develop with reversing valves is the solenoid can go bad and need to be replaced. Changing the reversing valve solenoid is an easy task compared to changing the reversing valve. There are those reversing valves that leak refrigerant from the high side to the low side or that refuse to shift and need to be replaced and to resolve this heat pump problem an HVAC technician with good brazing skills needs to replace the reversing valve. It will require all the refrigerant be evacuated and after the reversing valve is replaced the system will need to be recharged properly.
Heat Pump Problems - Back-up HeatingThe next item specific to heat pumps that has had problems historically is with electric back-up heat and systems that only have sequencers. A sequencer is an electric relay that will stage the heat strips for multistage heat strips. This is generally the case with larger systems and the engineer does not want the whole system to energize at once but instead stage the electric strips to come on slowly in a sequence. There specific reasons for this however the problem with some sequencers is the contacts inside the sequencer will not work properly and the sequencer needs to be replaced. Again, this is high voltage and needs the attention of a professional familiar with the unit as there is a shock hazard involved and can be very dangerous.
Heat Pump Problems - ConclusionThese are items specific to a heat pump that can give you problems with your heating system and without being specifically trained in the proper safety procedures for and handling of refrigerant it is best to call and HVAC technician to repair your system. We hope this helps you fix the heat pump problem. For an additional resource regarding heat pumps click here.