Thermostat Installation

It’s stopped working, it’s not working properly, or it just seems broken.

Why it happens: Usually flat batteries, settings changed by accident, a lost connection to the boiler, or the thermostat itself has failed.

Try this first: Change the batteries, even if the screen still shows something. Check it’s set to heating and the temperature is higher than the room.

What I do: Find the fault the same day and either fix it or replace the thermostat. Fixed price agreed before I start. Supplied and fitted from £199.

Why it happens: Battery thermostats go blank when the batteries die. A wired thermostat goes blank when it loses power, often from a tripped fuse or switch.

Try this first: Change the batteries. If it’s wired, check the fused switch that powers it and your fuse box.

What I do: Test the power and wiring, and replace the thermostat if it has failed. Supplied and fitted from £199.

Your old dial thermostat no longer clicks when you turn it up.

Why it happens: The click is a switch inside the dial. When it wears out, it stops telling the boiler to come on.

What I do: Replace it with a digital, wireless or smart thermostat. Fit only £120, or supplied and fitted from £199.

You’ve fitted a new thermostat and now there’s no heat.

Why it happens: It’s been wired to the wrong terminals, it hasn’t been paired with the receiver, or a link at the boiler was left out.

Try this first: Check the receiver at the boiler has power and follow the pairing steps in the manual.

What I do: Correct the wiring, pair it and test the heating comes on. Fit only £120.

The heating won’t come on even though the thermostat is turned up.

Why it happens: The set temperature is lower than the room, the timer is set to off, or the boiler has a fault.

Try this first: Set the thermostat 3 degrees above the room temperature, check the timer is set to heating, and look for a fault code on the boiler display.

What I do: Find out whether it's the thermostat or the boiler and fix it. If it's the boiler, see my No Heating page.

The boiler doesn’t respond to the thermostat at all.

Why it happens: The receiver at the boiler has lost signal or power, the wiring has a fault, or the boiler itself isn’t firing.

Try this first: Check the lights on the receiver near the boiler. If they’re off or flashing red, it has lost power or signal.

What I do: Test the receiver, the wiring and the boiler, and fix whichever has failed.

The thermostat and boiler aren’t talking, including Honeywell, Drayton, Hive and Ideal wireless thermostats.

Why it happens: Flat batteries, a power cut that wiped the pairing, or the thermostat is too far from the receiver.

Try this first: Change the batteries, then pair the thermostat and receiver again using the steps in your manual.

What I do: Pair it, move the receiver or thermostat for a better signal, or replace whichever part has failed.

Why it happens: The click means the thermostat is working. The problem is further along: the boiler, a valve or the pump.

Try this first: Check the boiler for a fault code and check the pressure is between 1 and 1.5 bar.

What I do: Find and fix the fault. More on my Boiler Repair page.

Why it happens: A switch inside the thermostat or receiver has stuck on, or there’s a wiring fault.

Try this first: Turn the heating off at the programmer or the boiler to stop it running.

What I do: Replace the faulty thermostat or receiver, usually the same day. Supplied and fitted from £199.

The house is too hot or too cold whatever you set it to.

Why it happens: Most often the thermostat is in the wrong place. Next to a radiator or in sunlight it thinks the house is warm. In a cold hallway it thinks the house is cold.

Try this first: Check what’s near it. If it’s wireless, try it in your main living room.

What I do: Move it to the right spot. A wired thermostat can be swapped for wireless so it goes anywhere. Fit only £120.

The timer isn’t turning the heating on at the right times, or the control panel doesn’t respond.

Why it happens: The clock has reset after a power cut, or the programmer has failed.

Try this first: Check the time and the on and off times are set correctly.

What I do: Replace the programmer with a simple one you can actually use. Supplied and fitted from £199.

The heating dial on the boiler itself doesn’t change anything.

Why it happens: That’s the boiler’s own temperature sensor or dial, not a room thermostat.

What I do: Repair the boiler. More on my Boiler Repair page.

Homes with separate upstairs and downstairs heating have a thermostat for each, and one has stopped working.

Why it happens: That zone’s thermostat, receiver or the valve it controls has failed.

What I do: Test the zone and repair or replace the failed part.

Why it happens: Older systems run on the boiler dial and a timer only, so the heating runs until the timer turns it off, however warm the house gets. That wastes gas.

What I do: Fit a room thermostat so the boiler only runs when the house needs heat. Supplied and fitted from £199.