Installing Rad Thermostat

[Geoff Lane]

I've got a Combi boiler system, three of my rads have no thermostat fixed and I want to fix one to two of them.

Do I have to drain the entire system to do so of is there a way round this.

Geoff Lane

[Set Square]

You'll have to at least partially drain it - and obviously the rads themselves.

Start with one of the rads. If there's a drain c*ck in the pipe next to one of the valves, use that - with the valve open - to drain the rad and pipe in one go. If there isn't, it gets a bit messier. Priceed as follows:

Turn off both valves tightly. Partially undo one of the unions between rad and valve, and collect the water from the rad in a container. Undo the bleed screw on the rad.[Use lots of old towels to protect any carpets from foul black staining liquid.]

When the rad is empty, fully undo the union plus the one the other end - and lift the rad off its brackets. [While it's off, take it outside and give it a good wash out with a hosepipe].

At this stage, the pipework is still full of water - only the rad is empty. Decide which valve you're going to replace with a TRV. Drain down the pipework feeding that valve into a container by opening the valve. When no nore water comes out you can remove the valve from the pipe and fit the TRV instead.

Swap the tail in the radiator with the one which came with the TRV. [This is most easily done with the rad lying down on a Workmate or similar]. You can then re-hang the radiator and connect the valves to the tails.

Then do it all over again with the next rad!

[Dave Plowman (News)]

Unless it's been done recently, it's no bad thing to drain down, flush through until the water runs clear and re-fill with fresh inhibitor.

The other way is to freeze the pipes, but this is an expensive option.

[Geoff Lane]

Thanks for very in depth reply; I've fitted a rad with thermostat before but some years back and forgot the procedure.

One will definitely be a new rad as well.

Geoff Lane

[Geoff Lane]

Forgot about that one but pound to a penny something wouldn't go smoothly and it'd thaw out anyway :-)))

Geoff Lane