Introduction – Heat Pump Not Cooling Or Heating
We have extolled the virtues of a heat pump for heating and cooling. These devices run off electricity or solar, so benefit from a grid moving toward renewables, and are very efficient. A heat pump is an energy-efficient heating and cooling system that works by transferring heat from one place to another.
A heat pump is exactly an air conditioner that is run in reverse and forward modes for heating and cooling respectively. Its heating mode is unlike a furnace, which burns fossil fuels to convert chemical bond energy into heat energy, instead using the principles of thermodynamics to move heat.
Common Reasons Of Heat Pump Problems
Before we begin, consider that the heat pump is actually ok and what you perceive to be a problem is part of its normal operation. Look through the manual, do a web search, check with an HVAC expert.
Otherwise, yes its true, heat pumps can malfunction, resulting in inadequate heating or cooling. For example the heat pump might not be blowing hot air, or the heat pump cools but does not heat. Conversely instead of not heating the heat pump is not cooling, or the air coming out is not cold. Common causes of heat pump failure include inadequate sizing, issues with the refrigerant, thermostat malfunction, clogged filters, and faulty electrical connections. In this article, we will discuss the most common reasons why a heat pump may not be heating or cooling.
Reason 1: Heat Pump Sizing Is Incorrect
If the unit is running and the right temperature air is coming out, but your space isn’t gettging comfortable, the sizing could be wrong. When it comes to selecting the right size heat pump for a home, it is important to ensure that the unit is sized properly to meet the needs of the home. A unit that is too small may likely not be able to effectively heat or cool the home, while an overly large unit may short-cycle, resulting in inefficient operation.
Potential causes of undersizing a heat pump include selecting the wrong size unit for the home, improper installation, and improper calculations of the heating and cooling load. It is important to consult with a qualified HVAC professional to ensure that the heat pump is sized correctly. The sizing is very similar to ACs, rated in terms of “tons” which can be converted to kWh or MMBTU. We had sized this before for air conditioners. For convenience we create a heat pump sizing chart for you here.
| Heat pump size | Annual electricity MBTU (kWh) | Summer monthly MBTU (kWh) | Home Size |
| 1 ton | 6.4 MBTU (1,867 kWh) | 2.1 MBTU (622 kWh) | 500 sq ft (apartment) |
| 2 tons | 12.8 MBTU (3,734 kWh) | 4.2 MBTU (1,244 kWh) | 1,000 sq ft |
| 3 tons | 19.2 MBTU (5,601 kWh) | 6.3 MBTU (1,866 kWh) | 1,500 sq ft |
| 4 tons | 25.1 MBTU (7,467 kWh) | 8.4 MBTU (2,489 kWh) | 2,000 sq ft (average house) |
Reason 2: Refrigerant Levels Have Dipped Too Low
If the heat pump seems to be working hard but the air isn’t the right temperature, this could be due to the refrigerant. The refrigerant in a heat pump is responsible for carrying the heat from one place to another. Issues with the refrigerant can cause a heat pump to fail to effectively heat and cool a home. Common problems that may arise with the refrigerant include leaks, improper pressure, and clogs.
If any of these issues arise, it is important to seek out a qualified HVAC technician to repair the problem. Steps for repairing refrigerant issues typically involve checking for leaks, inspecting the pressure, and flushing the system to remove any clogs. The technician may need to add more refrigerant, repair any leaks, or replace the refrigerant with the correct type.
Common types of refrigerants specified by manufacturers are R22, R32, R454C. The desired end pressure of refrigerant in a running heat pump will have a “low pressure” and a “high pressure” side corresponding to different stages of the cycle. On the low pressure side the desired reading we estimate to be 75-80 PSI whereas the high pressure side the desired reading we estimate to be 225-250 PSI.
Reason 3: The Thermostat Has Become Defective
If the heat pump seems insensitive to your interior temperature, this could be due to the thermostat and controller. The thermostat is a critical component of a heat pump, as it controls the temperature of the home. A malfunctioning thermostat can lead to inadequate heating or cooling. Possible causes of a thermostat malfunction include a dead battery, incorrect settings, or a faulty thermostat.
To troubleshoot a malfunctioning thermostat, it is important to check the batteries, reset the settings, and ensure that the thermostat is in the correct mode. If the issue persists, it may be necessary to replace the thermostat. The thermostat is not only a sensor but also a controller and will contain electronic parts for the heating and cooling logic.
Reason 4: Filters Are Too Clogged
If the heat pump is running, and the other causes above are eliminated, it could be the filters that are acting up. One of the most common causes of poor heat pump performance is a clogged filter. It is important to check the air filter on a regular basis and to replace it when it is dirty. A clogged air filter can inhibit the performance of a heat pump by restricting the airflow and causing the evaporator coil to freeze up. It is important to check the filter on a regular basis and to replace it when necessary to ensure that the heat pump is working properly.
The air filter in a heat pump could be checked as often as on a monthly basis and replaced when it is dirty. In practice you might want to check this once every two or three months. Depending on the type of filter, the frequency of use and the air quality, it may need to be replaced more or less frequently.
Reason 5: Faulty Electrical Connections
The heat pump, consisting of the outside compressor and the indoor air handler unit, could be just not running. Above we had listed a number of mechanical problems. In contrast, faulty electrical connections are also a major cause heat pump malfunctioning which will cause a part of the device to not do anything.
Potential electrical problems that may occur include loose or corroded wires, faulty circuit breakers, and broken components. To diagnose and fix electrical connections, it is important to check for loose or corroded wires, reset the circuit breakers, and inspect the components for damage. If any of these issues occur, it is important to consult with a qualified HVAC technician to ensure the connections are secure and functioning properly.
Conclusion – Heat Pump Not Cooling Or Heating
In conclusion, the most common reasons why a heat pump may not be heating or cooling include inadequate sizing, issues with the refrigerant, thermostat malfunction, clogged filters, and faulty electrical connections.
To keep a heat pump running smoothly, it is important to ensure that the unit is properly sized, the refrigerant is in good condition, the thermostat is functioning correctly, the filters are regularly checked and replaced, and the electrical connections are secure.
