Heat pumps are an efficient and effective method of cooling and heating your Chicago area home. They heat your home with much more efficiency than a gas furnace, and rival high-efficiency A/Cs for cooling. But without maintenance and repair, heat pumps can develop problems that can interfere with the system's performance. Here is a brief guide to identifying and troubleshooting heat pump issues.
Basic Heat Pump Operation
Unlike furnaces, heat pumps do not generate heat. Instead, they transfer existing heat from place to place, removing it where it's not wanted and bringing it into spaces that need to be warmed. When in cooling mode, heat pumps operate like central A/Cs, removing heat from the home, to create cooling.
The most common type of heat pumps are air-source models, which use the air surrounding the unit as the source of heat capture and release. Heat for warming your home can be acquired even from cold outdoor air, although this becomes more difficult in extreme temperatures. Geothermal, or ground-source, heat pumps use the soil outside your home for absorbing and releasing heat. Another type of geothermal unit, a water-source heat pump, uses a pond, aquifer, well, or other body of water as the heat source.
Heat transfer is accomplished by using a liquid refrigerant circulated between the indoor and outdoor components of the air-source heat pump. As the refrigerant travels through the lines, it changes state from liquid to gas and back again. This change of state allows the refrigerant to either absorb or release heat. When an air-source model provides heating, for example, the refrigerant is evaporated in the outdoor unit. As it evaporates to gaseous form, it picks up heat from the air. The gaseous refrigerant circulates indoors, after being compressed back into a liquid. As it changes state again, the refrigerant releases the heat it contains. Heat exchangers transfer this heat to air that is blown into your home by powerful fans. When the heat pump provides cooling, the refrigerant flow is reversed, which allows the refrigerant to capture heat inside your home and get rid of it outdoors.
Troubleshooting for Heat Pump Issues
When heat pump issues develop, take the time to try a few troubleshooting techniques before you call your HVAC professional:
- Nonfunctioning unit: If the heat pump doesn't work at all, make sure it's still properly connected to a power source and that the power is switched on. Check circuit breakers on the heat pump itself and at your home's main breaker box to ensure no breakers have been tripped. Reset any tripped breakers to see if that solves the problem. If breakers continue to trip repeatedly, call an electrician or HVAC professional for help.
- Heating or cooling problems: First, check the thermostat and make sure it's set to an appropiate temperature for the season. Also make sure it has been set to heating or cooling mode, as needed. A simple error at the thermostat could prevent your heat pump from working correctly. Check the system's air filter to make sure it's not clogged or dirty. Air filters in bad condition are prime causes of HVAC system malfunctions and breakdowns, since the clogged filter interferes with the airflow the system needs to operate. Change the filters if they're dirty.
- Cycling problems: If the heat pump doesn't cycle correctly and fails to provide appropriate cooling or heating, check the thermostat to make sure it's reads the indoor temperature correctly. If the thermostat is in direct sunlight, near a heat source, or is placed in a cool zone, it won't provide accurate readings. A dirty filter also could be a cause of cycling problems; check and change filters, as needed.
- No airflow from vents: If no heated or cooled air is exiting the vents, make sure the dampers in the registers or ductwork are open to allow plenty of airflow. Check all vents to ensure nothing is covering or obstructing them, such as furniture, clothing, boxes or other items. Take a look at the blower fan to make sure that it's moving air from the heat pump to the ductwork and into your home. Check the blower fan belt to see if it's damaged, broken or detached. Replace the belt if necessary.
Heat Pump Issue: Freezing Over
A common problem with heat pumps is the outdoor unit freezing over during heating operations. There will normally be frost or ice on the outdoor coils as part of normal heat pump function. As this frost or ice builds up, it's detected by the heat pump's sensors. The unit defrosts itself by shifting temporarily into cooling mode to move hot refrigerant through the outdoor coils. Supplemental heating units continue to provide indoor heating while the hot refrigerant removes the frost and ice, then the unit shifts back to normal heating mode.
If this defrost cycle malfunctions, large amounts of ice can build up on the heat pump's outdoor unit. Repeated problems with freezing can damage the unit and eventually cause it to fail completely, requiring a total replacement.
As soon as you notice a significant ice accumulation on the heat pump, shut the system off and call your local trusted HVAC professional for service.
Heat Pump Issue: Blowing Cold Air
Another common issue with heat pumps is the complaint that they are blowing cold air. It's true that the air coming from a heat pump may feel cooler than what a standard gas or electric furnace produces. However, this does not necessarily mean that the heat pump is producing cold air. The air coming from the heat pump is typically going to be above room temperature, which means it's fulfilling its heating function. What is usually happening in these cases is that the heat pump is producing cooler air than a furnace, but is still providing above-room temperature for a longer period than a furnace. This means that the temperature in your home increases more gradually and consistently. Before calling for a service appointment, measure the temperature of the air coming out of the heat pump. If the air is above room temperature, the heat pump is doing its job.
Heat Pump Issue: Maintenance
Regular preventive maintenance is the best way to avoid heat pump issues. Maintenance should be performed at least once a year. However, since heat pumps are used during both heating and cooling season, it's better to schedule maintenance tune-ups and inspections in both spring and summer.
Your HVAC professional should be able to fix small problems before they can become major performance issues. He can also tell you if larger issues are developing that may require more attention or a greater repair effort later. In total, preventive maintenance keeps your heat pump working at its best for as long as possible, extending system life while boosting efficiency and performance.
As part of the preventive maintenance appointment, your HVAC technician will perform tasks such as:
- Check and calibrate controls: The technician will make sure the thermostat and other important system controls are properly calibrated and adjusted to ensure the best possible performance. Malfunctioning controls can usually be replaced, if necessary.
- Check refrigerant levels: Your heat pump requires a specified amount of refrigerant for proper operation. The technician can check the level of refrigerant in the heat pump and add more if needed. If refrigerant is being lost, the technician should also check for and repair any leaks in the refrigerant lines or connections.
- Inspect ductwork: Air loss in the HVAC system ductwork can cause serious degradation of heat pump efficiency and performance. The tech should check the ductwork and make sure that all duct connections are tightly sealed and insulated to prevent energy loss.
- Clean and tighten electrical connections: Over time, electrical connections can become loose and dirty. Your technician should clean these connections, add a nonconductive coating, and tighten them to ensure proper function.
- Check and service system components: All relevant system components should be inspected and serviced. This includes lubrication of motors and moving parts, tightening of belts, and verification of all controls.
Your HVAC technician will perform a complete system check if requested, but there are a few things you can do to help. By doing these simple tasks, you can free up more of the technician's time to focus on technical issues, adjustments and repairs.
- Change the air filter
- Clean the indoor and outdoor coils
- Clean the outdoor unit of accumulated dirt, vegetation or other material
- Clean indoor registers and vents, and ensure they're not blocked
- Clean and oil the blower fan (if it's accessible)
Comfort24-7 can help you find an HVAC expert for service, maintenance and repair in northern Indiana, southwestern Michigan and the Chicago area. Contact us today for more information on resolving heat pump issues.
Written by Randy Gailit