Heat Pump Troubleshooting Guide


For most of the time your heat pump should operate without any need for adjustment. However, occasionally you may experience some problems. This guide is intended as a reference to help you to get the heat pump working as quickly as possible and to save you money on call-out fees. While some of the advice below may seem obvious, these are common reasons that we have discovered for heat pumps that are not working as desired.

Heat is not reaching radiators / underfloor heating

You may find that the radiators or underfloor heating pipes do not feel hot. Heat pumps provide a lower flow temperature (45-50°C) than traditional boilers (60-70°C). During the summer months the flow temperature can be reduced to 35°C. This flow temperature is enough to warm the rooms in your house to between 18°C and 21°C, but does not feel hot to the touch because your natural body temperature is around 37°C. So rather than check that the radiator heats up, it is better to check whether the room reaches the correct temperature after a few hours.

If the room is not reaching the desired temperature, try checking the following:

Check the heat pump control board for error messages
If you have a Kensa ground source heat pump and it is displaying an error message, check the Kensa user guide (page 18) for instructions to correct simple common faults.

If there is a message on the control board in the form of a code number, or if you do not understand the message, make a note of it and call us for advice.

Check that radiator control valves are open
Most modern radiators have a control valve on one of the corners. Make sure these are open.

Where is the thermostat?
If you have a remote thermostat, check where it is – if it is close to a heat source, such as a wood burner or a radiator in a different room, the thermostat may detect that the temperature has been reached and will turn off the heating in that zone, so other rooms in the zone will not get heat.

Check the thermostat setting
The thermostat should be set at the desired temperature of the room that it is in. This is normally between 18°C and 21°C.

Check the batteries in the thermostat
If you have a remote thermostat, check that the batteries are working.

Is the heat pump on a hot water cycle
When the heat pump is heating the hot water in your cylinder, it does not provide heat for the space heating circuit.

If you have a Mitsubishi air source heat pump, you can check whether it is on a hot water cycle by referring to the Quick start guide for FTC 3 & 4 or FTC 5* (Page 7 – icon 11).

Once the hot water cylinder has been heated, the heat pump should switch back to space heating. If it does not, check whether the hot water taps/showers in the building are running – If a hot water tap has been left running, the cylinder will never reach the desired temperature and the heat pump will be stuck on the hot water cycle.

* You can find out which FTC (Flow Temperature Controller) you have by checking the label on your hot water cylinder. The FTC 5 was released in 2015, so if your heat pump was installed before then, it is probably FTC 3 or 4, and if it was installed after 2015 it is probably FTC 5.

Space heating prohibited mode
For Mitsubishi air source heat pumps, see the Quickstart guide (see links above – Page 7, Icon 13) to determine if the system is in space heating prohibited mode.

Obstructions (Air source heat pumps)
Is there anything in front of, or down the back of, your heat pump unit, obstructing the flow of air? If so, remove the obstruction. The heat pump needs a clear space of 10cm behind and between 0.5m and 1m, depending on the model, in front of the unit to allow the air to flow through efficiently. Obstructions, such as false hedges, garden furniture or building materials, in front of the unit can make the heat pump work less efficiently.

The heat pump is using more electricity than expected

The heat pump was designed to heat the building to an average temperature of around 20°C, with the thermal properties of the building at the time of the installation. The estimate of the running cost in the quote were based on this average temperature.

Are there windows open?
If you like to keep windows open to allow fresh air into the house, try opening them for a short time (up to one hour) to allow in the fresh air and then keep them closed for the rest of the day.

Check the thermostat(s)
The thermostat should normally be set at between 18 and 21°C, depending on which room it is in. If it is set higher, the heat pump will work harder to maintain that temperature and will demand more electricity to run.
If you have a remote thermostat, and it has been left in an unheated room, it will continue to call for more heat. Move the thermostat into a room where the heating is on.

Obstructions (see above)

Call us

If you have checked all of these and you still cannot find the problem, give us a call, either on our office line (during weekdays only), or on the dedicated maintenance phone line (available at weekends), which is available to all customers on our service and maintenance plan. Please give us as much detail about the problem as possible, including any error messages on the control board and what you have already checked. We will try to identify and solve the problem over the telephone, and if we can’t, we will arrange to come and check the system.

If you have our service and maintenance plan, the visit will cost £30, all labour costs thereafter are included in your plan as well as replacement parts within warranty or up to the value of £500. If you do not have our service and maintenance plan, we charge £85* for a call out lasting up to one hour, and £45 per hour for any repair work thereafter. We will provide a quote for any new parts and estimated labour for any repairs that are required and will ask for written confirmation to proceed, before carrying out any work.

* The standard call-out rate of £85 is for properties within 25 miles (40km) of Harrogate. For locations outside of this radius we will let you know the call-out fee when you call to arrange the visit.