5 Reasons Your Underfloor Heating Thermostat Isn’t Working

A thermostat is an essential component of every heating system but occasionally they can begin to malfunction. Is your thermostat not working? There could be a number of reasons why a thermostat has stopped working including the boiler not working with thermostat and the thermostat not turning on the heat when you need it. In this article, we take a look at 5 reasons why your underfloor heating thermostat isn’t working and examine the possible causes. If you need help fixing your thermostat issue then read on.

1. Your thermostat won’t turn on or the display is blank

The main reason why a wireless thermostat might not work is simply because the battery is being discharged. It’s an obvious cause but very often overlooked because many people tend to forget that their thermostat relies on battery power. Changing the battery is the solution to most thermostat problems including a slow response time. It’s always a good idea to keep a spare battery handy just in case.

Another reason why you might find your heating thermostat not working or not responding is because the circuit breaker has been tripped. This only applies to thermostats that are wired into the mains electrical supply. Check your fuse box to see if the breaker has been tripped and then reset it. If this continues to happen then it could be a sign that an electrical fault has developed, which will need to be checked out by a qualified electrician.

2. Your thermostat won’t let you change the temperature setting

You know you have a problem with a thermostat not working when it won’t let you change the temperature setting. This is quite a common problem and can easily be rectified by moving the thermostat to a different position or to a different room. However, the cause could be down to a malfunctioning sensor, in which case this would need to be replaced by the manufacturer.

Some thermostats have a child lock setting and if this has been activated then you will not be able to adjust the temperature. Check and disable the setting before trying again. A dead or weak battery could also be causing the problem so check this too. Sometimes the build-up of dirt and dust can have a bearing on your thermostat’s responsiveness so try wiping over the unit with a clean, damp cloth.

3. The heating isn’t reaching your thermostat’s set temperature

With a thermostat not working properly you might experience a lower than expected room temperature. When your underfloor heating isn’t reaching your thermostat’s set temperature in all rooms then there could be a problem with your home’s insulation. If the problem only occurs in a particular room then there could be an issue with airflow such as a door or window being left open. Kitchens are less likely to reach the set temperature due to space being taken up by fixtures and fittings around the floor area.

If you have a water-based underfloor heating system installed then the problem could be trapped air. Try bleeding the system to see if that makes a difference. If it doesn’t then the problem could be a faulty thermostat so first check the settings. Before considering a replacement, try cleaning the thermostat to remove any dirt or dust deposits and change the battery.

4. Your thermostat is not working with the boiler

When a thermostat is not connecting to the boiler, there is no communication, which means whatever setting your thermostat is on, it will not work properly. Your water underfloor heating thermostat must be in contact with your boiler so that it can respond to your settings. Otherwise, the heating can just come on unexpectedly or go off when you need it most. The first thing to consider is interference from WiFi routers, smart TVs, smart fridges and game consoles. These operate at frequencies and wavelengths that can interfere with other wireless signals.

Try moving the wireless thermostat to a new position in the room or to a different location. Ensure that it is not too far away from your boiler and in an open position, rather than in an airing cupboard. Keep it away from any heat source such as a boiler or portable heater as this will cause the thermostat to switch off sooner than expected. Once again, if that doesn’t work then check the battery and clean the thermostat unit with a damp cloth.

5. Your thermostat is displaying the wrong temperature

If your underfloor heating thermostat is reading 25° when it’s clearly less than 20° in the room, there could be a problem with the thermostat’s internal sensor. However, it is more likely to be a heat source affecting the thermostat such as the sun shining through a window directly onto the wireless thermostat. Ensure your thermostat is located away from heat and draughts and is placed 5 feet from the floor in a central position within your home.

If repositioning the underfloor heating thermostat doesn’t solve the problem then try changing the battery and cleaning the unit. Assuming the underfloor heating system has been installed correctly, including the floor sensor, if the problem persists then there may be no other option but to replace the thermostat unit. If your heating system is using an old thermostat with a mercury bulb then a modern alternative should seriously be considered.

When to replace your thermostat

There comes a time when despite checking everything, including changing the battery and cleaning the unit, your heating thermostat is still malfunctioning. With your heating thermostat not working and no control over your heating needs, run through this final checklist before buying a new thermostat. If your answer is a resounding ’no’ to all the questions then it’s time to replace.

1. Does your thermostat respond to a new setting?
2. Is your thermostat displaying the correct room temperatures?
3. Are you able to save the settings on your thermostat?
4. Is there anything being displayed on your thermostat?
5. Has restarting the boiler had any effect on your thermostat?

As a final check, try resetting the thermostat. To do this with a digital thermostat, remove the batteries and re-insert them the wrong way around. Wait 5 seconds and then change them back. Some thermostats have a recessed reset button you can press by using a paper clip. Hold the button in for 5 seconds and then release. A mechanical thermostat can be reset by turning it off and then flipping the circuit breaker. Leave it off for 30 seconds and then switch it on again.

A fault can develop with a thermostat if it is old and worn out. Also, any thermostat that is not working correctly could have an adverse effect on your heating bills so it’s an issue worth taking the time to correct as soon as possible. If all else has failed and you need to replace your faulty thermostat unit, it is recommended you choose from a selection of wireless smart thermostats.