Smart thermostats: what an electrician does and does not do

A smart thermostat looks like a single product to buy and fit, but the job behind it usually splits across more than one trade. Knowing which part is electrical work and which is not saves an awkward call-out where the wrong person turns up for half the job.

The wiring an electrician actually touches

Most smart thermostats replace an old mechanical dial or a simple programmer, and the cable run behind the old one was often never built to power a device with a screen and a wireless radio. An electrician's part of the job is usually running a new cable where one is needed, working on the wiring centre that connects the thermostat to the heating system, and fitting a socket nearby for a hub or receiver where the thermostat needs one. It also means checking that whatever cabling is already there is sound before anything gets connected to it.

Where the boiler side is someone else's job

Where the boiler itself runs on gas, anything that involves opening the appliance, its burner, its flue, or its gas valve settings is Gas Safe registered work, not electrical — an electrician can wire up to the boiler's external terminals but has no business inside the casing of a gas appliance. For an electric boiler the picture is different again, and that is electrical work throughout, which is worth knowing before you book the wrong trade for the wrong half of the job.

What the manufacturer decides, not the trade

Which boiler models a given smart thermostat works with, how the app pairing goes, and which features actually function together are decided by the manufacturer's own compatibility list and installation instructions, not by a generic wiring diagram. Check your boiler against the thermostat's own compatibility information before buying, because that is the part no electrician can wire around.

• Check the thermostat's own compatibility list against your boiler before buying, not after it arrives.
• Expect an electrician to handle the wiring centre, any new cable run, and a socket for a hub where one is needed.
• Expect anything inside a gas boiler's casing, its flue, or its gas settings to be Gas Safe registered work.
• Keep the old wiring diagram or a photograph of the original connections before anything is disconnected.

We handle the wiring centre work and cabling a smart thermostat needs, and we'll say plainly when a job belongs with a Gas Safe engineer instead, as part of general heating electrical work across London, Essex and north Kent.

If you are unsure, it is always cheaper to ask than to guess. Give us a call and we will tell you straight.