Switching Boiler Thermostat/Programmer

youngh90

I currently have a Worcester Greenstar Si Compact boiler and the programmer on the boiler itself consists of little sticks that, when pushed in, set the heating to on and, when pushed out, set the heating to off. These are really fiddly and I now need to change these most days so it's not a suitable system.

I also have a separate basic dial thermostat in the living room which controls the temperature.

I'm looking to replace both of these with one single digital thermostat and programmer. Is it possible to do this (override the timer on the boiler itself) and is it something that could be installed DIY?

Cornucopia

Generally speaking, yes. It is a job I have done myself.

I set the Boiler to Continuous, and replaced the thermostat with a combined Timer-Thermostat unit. This provides for temperature-time programs with overrides, holiday mode, etc. You can buy these from Screwfix, Toolstation, etc., starting from about £20.

The only issue is ensuring that the wiring from the Boiler to the old Thermostat is compatible with the new Thermostat. Many of the cheaper (new) thermostats will be battery-powered, which means that the wiring can be the simplest on-off switch, with no need for power, which may or may not be present.

It's a simple enough job for someone reasonably comfortable with electrical wiring.

edit: I have this one, which seems to work quite well, although the click on and off is louder than I would prefer.



https://www.screwfix.com/p/iqe-7-day-programmable-room-thermostat-with-li-ion-battery-back-up/53575

SuzieSue

I did exactly did this a few years ago, but had to get an electrician to wire it as I couldn't work it out myself.

I got this one:

https://www.amazon.co.uk/gp/product/B003EQCTFQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

benjus

As others have said, it's pretty easy - at the moment you have 2 devices that act as switches: one is the timer on the boiler, the other is the room thermostat. The heating only comes on if both switches are ON. So you replace the thermostat with one that also includes a timer, and set the boiler's timer to always on.

However, if your boiler is also used for hot water and your new thermostat offers hot water control that you would like to use, this will have to be wired up separately - and exactly how to do that will depend on your system. It's probably easier to stick with whatever you're using now for hot water and just change the heating controls.

wantonnoodle

That is precisely how a Nest system works. Boiler is set to always on, and then the nest links in and controls time and temperature. Our DHW is on demand though so don't know how it works if DHW is through a tank - though I know looking at the nest website it is possible.

Not possible to fit DIY though. Its possible to buy a nest kit with fitting included - you get a voucher in the box that you can use to arrange fitting.

Debbie_Savard

Yes, done this with a combi using a Drayton Digistat +3RF.

Just set all the 'fingers' on the dial to On and wire the receiver unit to the call for heat input on the boiler and programme the controller to the temp profile you want.