If your heat pump is costing more to run than expected, the heat pump itself may not be the problem.
As heat pump installers covering Derbyshire and the Midlands, we often hear from homeowners who are disappointed with their system. Some say their electricity bills are too high, their home does not feel warm enough, or they wish they had kept their old combi boiler.
Unfortunately, many of these homeowners are experiencing the consequences of a poor design or installation.
A heat pump is only as efficient as the heating system around it. It must be correctly sized, properly controlled and designed to work with the radiators or underfloor heating and pipework within the property.
Here are some of the most common reasons a heat pump may be expensive to run.
The system was not designed correctly
A heat pump should be selected using a detailed heat loss calculation for the property.
If the unit is too small, it may struggle during cold weather and rely more heavily on its electrical backup heater. If it is oversized, it may regularly switch on and off, reducing efficiency and increasing wear.
The existing boiler size should never be used as the basis for selecting a heat pump.
The flow temperature is too high
Heat pumps generally work most efficiently when producing lower-temperature water over longer periods.
If the radiators are too small, the system may need to run at a higher flow temperature to keep the property warm. The hotter the water needs to be, the harder the heat pump has to work.
Correct radiator sizing is therefore an important part of any heat pump design.
The controls are not working properly
Heat pumps require a different control strategy from traditional boilers.
Incorrectly installed thermostats, motorised valves or timers can cause the system to repeatedly stop and start or work harder than necessary.
Weather compensation should also be set correctly. This allows the heat pump to adjust the water temperature according to the outdoor temperature, rather than producing hotter water than the property needs.
Pipework is missing insulation
Uninsulated pipework allows heat to escape before it reaches the home.
This is particularly important on external pipework or pipes running through garages, lofts and plant rooms. Any heat lost through the pipework has to be replaced, increasing electricity consumption.
The backup heater is running unnecessarily
Most heat pumps include an electrical backup heater.
This can be useful in certain situations, but it is much less efficient than the heat pump compressor. Incorrect settings, poor water flow or an undersized system may cause the backup heater to operate more often than necessary.
This can have a significant effect on electricity bills.
A real example from Chesterfield
We previously inspected a heat pump installation at a property in Chesterfield after the new owners became concerned about the running costs.
The family believed the heat pump was inefficient and questioned whether they would have been better staying with a boiler.
After investigating the system, we found that sections of pipework had not been insulated correctly. The electronic controls had also been installed incorrectly and were not communicating properly with the equipment.
The heat pump was operating, but the installation around it was preventing it from working efficiently.
The problem was not simply the heat pump. It was the way the system had been installed and set up.
Has the system been properly commissioned?
Commissioning is more than switching the heat pump on and checking that the radiators become warm.
The installer should check the water flow, balance the system, configure the heating curve, test the controls and confirm when the electrical backup heater is operating.
The homeowner should also receive a proper handover explaining how to use the system.
Heat pumps usually work best when maintaining a steady temperature, rather than being switched on for short bursts like a traditional boiler.
Do not blame the heat pump too quickly
When a boiler performs poorly, people often question the installer or the heating system.
When a heat pump performs poorly, the technology itself is often blamed.
In reality, heat pumps can work successfully in many different types of properties, including older homes. However, the design, installation and commissioning must be completed correctly.
Before considering replacing your heat pump or returning to a fossil fuel boiler, arrange for the full system to be assessed.
At The Thermal Heat Company, we provide heat pump servicing, fault finding and system assessments throughout Derbyshire, Tamworth and the Midlands.
Because a heat pump should not just be installed. It should be designed to last.
