Gas Central Heating - Upstairs Rads Stone Cold

Hi all,

I've read several threads I found in a search, some were useful but I don’t think any described my exact circumstances. I know very little about central heating, so keep that in mind.

We have just moved into a new property. It has a Logic Combi boiler and a Drayton programmer. Like much in the house they seem to be completely new. I’ve come to grips with the boiler generally, but while the downstairs radiators are quick to heat up and get very hot, the upstairs radiators (3 bedrooms and the bathroom) are stone cold. There isn’t a hint of warmth in them or the pipes leading to them. Hot water comes out of the bathroom tap fine.

There are thermostats upstairs and down, and I’ve fiddled with them but there has been no reaction upstairs. All rads are definitely open, I have not yet tried to bleed them, will do this evening hopefully, but given they are completely cold all over I’m guessing (maybe wrongly) that isn’t the problem.

Is there some switch or valve that could be faulty, or just not turned on?

Thanks in advance.

Sounds like the motorized zone valve is faulty. The thermostats are wired to the zone valves. These are probably located in your hotpress. It looks like a small box fitted to a pipe and it will have a wire coming out of it.

There should be a switch on the end of the valve that says Auto on one end and Manual on the other end. Switch it to Manual. This will over-ride the valve and leave in the open position. You may have to push the lever into a slot to hold in that position.

Turn on boiler and see if heat gets past the valve.

If not the valve, it could also be a faulty room thermostat. This can be tested with a continuity meter or see if you hear a click in the stat when you turn the dial and does it click at roughly the room temp.

Could be other faults, but these should be checked first.

+1 motor valve faulty/stuck

Cheers for that folks, you got it in one. Having moved the valve (there seems to be one for each floor) and slotted it into the manual position we now have heat upstairs.

Depending on the make and type of the valve, you should be able to just purchase the valve head from your local merchant and replace this without draining system. If not, purchase the complete unit but only use the new head.