Boiler Thermostat Not Working – How to Fix Guide Dan Bayliss April 3, 2023

Boiler Thermostat Not Working – How to Fix Guide

boiler thermostat not working

Is your boiler thermostat not working?

How to fix a boiler’s thermostat – the boiler and thermostat may have disconnected. This blog covers the possible causes.

When they are working, boiler thermostats or controls make life a lot easier. They allow us to control the temperature from a device on the wall or from a phone app (if it’s a smart thermostat like a Hive smart thermostat).

Boiler thermostats come in many different forms, and they are more advanced than ever, but the more advanced devices become, the harder it is to figure out why the thing isn’t working. In this guide, we’re going to look at the common problems that stop a thermostat from connecting to your boiler and heating the home.

Before we get started, let’s get a cheeky advertising plug-in – if you need a brand new smart thermostat or a new boiler (with or without a thermostat) fitted, then WarmZilla can help you. Get an instant online quote now. However, times are hard, so you’re probably looking to get that old thermostat back up and running. Let’s get to it!

Change the batteries

This may sound like a silly suggestion, but you’d be surprised how many times we’ve spoken to customers who are unhappy that their thermostats have stopped working only to find out that the issue is down to dead batteries in the thermostat.

This solution only applies to wireless thermostats, no need to start pulling those wired thermostats off the wall, they are powered by mains electricity.

Are the boiler and thermostat turned on?

Another fairly easy fix for this one, check to make sure both your boiler and the thermostat are actually turned on. Go and have a look at your boiler, swing that flap down and make sure there are no error codes and that the LCD screen is bright and active.

If there is a fault code on your boiler, just google the fault code and click on the WarmZilla blog that will come up (ignoring all cheap imitations 🙂)

Check your wireless thermostat is on, if not, change the batteries and then pair the thermostat with your boiler. You will need to refer to the manufacturer’s instructions for this as they all have a different and unnecessarily complicated way of pairing.

User error

It’s extremely unlikely, you don’t make many mistakes, but maybe, just maybe, you might have put the incorrect temperature into the app, or moved the dial to a rakish angle without meaning to.

Some apps also offer water and heating scheduling, perhaps you might have applied the temperature you wanted to the water scheduling side by mistake?

No? We didn’t think so. Don’t worry, we’re getting through the silly fixes, and on to the more technical fixes.

user error image

The average gas bill cost in 2023

The estimated annual gas bill for a medium-sized home with three bedrooms is around £1,345.96 – this works out to an average of approximately £112.16 per month. These figures can change based on gas prices and other factors.

Thermostat temperature sensor issue

The temperature sensor inside your thermostat is quite sensitive, so don’t scream at it to start working again, it won’t help. 

What might help though, is to gently clean the temperature sensor with a clean cloth.

Google Nest Smart Thermostat on wall

Thermostat location

A thermostat uses a temperature sensor to gauge the ambient temperature where it’s located. If you have your thermostat located in a room that is always cold or always hot, then it will have a difficult time regulating the temperature for the rest of your home.

Other factors that can affect a thermostats performance include:

  • Located in a room where the radiators have been switched off
  • Being in direct sunlight
  • Located in a draughty area

If your thermostat is located in your tropical greenhouse, then it’s going to think it’s doing a great job of keeping you nice and warm, while you’re busy freezing in the living room. Try to locate the thermostat controls somewhere that gives a good representation of the general temperature of the home.

If you have a wireless thermostat then you should be fine to move it yourself, they are generally fixed to the wall with a couple of screws. If you have a wired thermostat, leave it to someone who knows what they’re doing, because you’re dealing with live electricity.

Turn it off and back on again

You knew this one was coming didn’t you. Scientifically proven to fix 99% of all gadget related issues, the old classic, turn it off and back on again. 

To reset your thermostat, refer to the manufacturer’s instructions and follow them until you have successfully reset your stat. If you don’t have the manual, just Google it ‘How to reset a Google Nest Thermostat’ and you will have your answer.

More modern thermostats tend to have a reset button that you hold down for a specific duration and that resets them. Some older, and some cheaper brands have a 20 step plan you have to follow religiously to reset your thermostat.

Wiring issue (wired thermostat)

Sometimes a wiring issue can occur with a wired thermostat. Either the wiring going into the thermostat on the wall, or the wiring connecting the thermostat to the boiler is wired incorrectly. 

This would usually be when the installation is new, it’s unlikely something would go wrong with the wiring if nothing has changed in a while unless someone has been a bit overzealous in their DIY and cut or damaged the wire.

If there is an issue with the wiring, don’t try and fix it yourself, get a qualified electrician (sparky) to take a look at it for you.

Thermostats don’t last forever

If you’ve crossed off all the other reasons why your thermostat may not be working, and your thermostat is getting on in years, it might just be that it’s old and in need of replacement. Like boilers, thermostats tend to have a 10 – 15 year lifespan, after that, they become less reliable and prone to parts failure.

Signs your thermostat might be in need of a replacement include temperature fluctuation – if your temperature swings wildly between hot and cold, your thermostat probably has something to do with it. High energy bills can also be a sign of a faulty thermostat, although it may be difficult to tell a high energy bill at the moment, as they all seem pretty steep.

If you have an aging thermostat don’t feel bad for retiring it, the technology advancements in ten years is huge, giving you a whole range of new features on your thermostat that will save you money and offer you more convenience. Like geofencing for example, you can program your thermostat to turn your heating on when you are a certain distance from your home, pretty nice eh?

We’ve already looked at the best thermostats around in 2023, and done the research for you.

It’s the boiler’s fault

It may be that your poor thermostat is taking the blame for the boiler. If you can’t find anything wrong with your thermostat, it could be that there’s an issue with your boiler. Take a look and make sure there are no error messages displayed on the LCD display on your boiler.

Most modern boilers will lockout and display an error message if they detect an issue to ensure your safety. So if the boiler doesn’t have an error message displayed, it’s probably not the boiler.

How much does it cost to fix a thermostat?

Typically, the cost of repairing a thermostat will depend on several factors including the extent of the damage or problem, the type and brand of the thermostat, the cost of labor and replacement parts, and the hourly rate charged by the contractor or technician. 

The hourly rate of a heating engineer or an electrician is between £30-£50 per hour, depending on where you live.

Unless your thermostat is relatively new, it’s probably not cost effective to get it repaired. By the time you’ve paid a callout fee and the problem has been diagnosed and replacement parts ordered, you may as well have just bought a new one.

It’s worth checking whether or not your thermostat is still under warranty before making any decisions. You might be able to get it fixed for free.