Heat Pump Problems
Air source heat pumps are cheaper to install than geothermal heat pump systems. However, geothermal heat pumps will save a lot of money over the life of the heat pump in operating costs.
Geothermal heat pumps are more efficient than air-source heat pumps. There may be a time when your heat pump will begin giving you problems. We decided to post an article to help some people diagnose the heat pump problem. Remember always to be safe and do not go above your comfort level or skills. When in doubt, call a professional. Someone can do some minor repairs with minimal skills.
However, we always recommend you call an HVAC contractor to repair the problem. Especially the more significant issues that require specialized tools. Before you get started, you may want to take a look at a few of our other 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. Being familiar with heat pump components will also help you. Additionally, reading troubleshooting heat pumps and heat pump breaker trips will also help you.
Cold Weather Heat Pump Problems | Delta T(°F) Between Supply & Return and Balance Point
Problems with heat pumps can occur in hot or cold weather. The biggest complaint about problems with heats in cold weather is that the heat pump is blowing cold air. While the term “cold air” is relative, a real measurement of temperature should be taken to determine if the air is relatively cold or not. Since a heat pump is a forced air system and humans feel cooler when a draft is present, you will feel cooler when the air is blowing from a supply vent.
If the air is less than 98° F. then you will likely think the air is cold. Relatively speaking, 98° F. is much warmer than the air if it is wintertime and the outside air temperature is 45° F. This temperature output for a heat pump is dependent on a few factors. What is the temperature outside and are the electric heat strips on?
The chart below shows BTU output based on outside air temperature when the heat pump is in heating mode. MBh in the chart equals 1,000 BTU’s.
So you can see from the above chart that the amount of BTU’s produced by the heat pump drop as the temperature outside gets colder. So the balance point for your heat pump will be different than the balance point for another heat pump, and this will depend on outside air temperature, refrigerant type, and the size of the heat pump capacity-wise. I’ve seen charts on the web and other places that indicate you should get so and so much temperature difference between the supply and return.
Or so much temperature difference across the evaporator coil. However, unless you look at the datasheet for your particular heat pump and know whether the heat strips are on or off, you cannot get an exact number for the temperature difference in either location when in heating mode. In cooling mode, yes, but not in the heating mode because of all the variables. For further help, we cover heat pump problems on a component by component basis below.
Hot Weather Heat Pump Problems
For hot weather heat pump problems, the biggest complaint is no cooling. Since the heat pump is like an air conditioner you may also want to pop over to our air conditioner troubleshooting category to see if you can find help in identifying the problem with your heat pump in cooling mode. The difference in components from an air conditioner to a heat pump could be the problem, but we cover components below.
From my experience, getting trouble calls for no cooling for heat pumps in the summer, the most common problem was a low refrigerant charge due to a refrigerant leak. Other basic common problems include electrical problems such as a blown fuse, heat pump breaker tripping, bad run capacitor, or a bad compressor contactor. It is also possible to have an issue with your heat pump thermostat. For that, you can visit our heat pump thermostat troubleshooting page.
Heat Pump Problems - Accumulator
One 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. It does this, so the liquid does not harm the compressor.
It protects the compressor in the winter. It is an essential component to prevent other problems with the compressor. The problem with all the accumulators is they are made out of steel. Accumulators are exposed to the environment and 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. The heat problem will start with a pinhole leak allowing refrigerant to leak out. Eventually, the heat pump stops working until the 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 - Defrost
The next heat pump problem on the list is the heat pump defrost board. The defrost board controls the defrost in the colder months. The heat pump condenser operates 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 need to be removed. Therefore, the heat pump is equipped with a defrost cycle that will change the unit over to the cooling cycle. That causes the condenser coils to heat up and melt the ice.
At the same time, the defrost control board activates the heat strips or backup heat inside the air handler. That is done, 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. However, the 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. The defrost control boards are usually located inside the condenser cabinet with high voltage. There is a danger involved in changing a defrost control board.
The Reversing Valve
Specific to heat pumps the next problem one can encounter is the reversing valve. The reversing valve will shift from cooling to heating mode. Then back again, depending on the setting of the heat pump thermostat and defrost control. 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. Some refuse to shift and need to be replaced. 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 to be evacuated. After the reversing valve is replaced the system will need to be recharged properly.
Back Up Heating
The next item specific to heat pumps that have had problems historically is with electric backup heat and systems that only have sequencers. A sequencer is an electric relay that will stage the heat strips for multistage heat strips. That 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 are specific reasons for this sequence. However, the problem with some sequencers is the contacts inside the sequencer will not work properly. In this case, the sequencer needs to be replaced. Again, this is high voltage and needs the attention of a professional familiar with the unit. There is a shock hazard involved and can be very dangerous.
Heat Pump Problems - Conclusion
These are items specific to a heat pump that can give you problems. Specific problems can occur with your heat pump system. Some of these things require specific training in the proper safety procedures and for and handling of refrigerant. Sometimes it is best to call an HVAC technician to repair your system. We hope this helps you fix the heat pump problems.
Heat Pump Problems