CH zone actuator replaced, now struggling to get up to temperature.

TadleyBaggie

Up to 2 days ago the CH was working fine, setting the thermostat to 20C would cause the house to easily reach that temperature and be maintained. Yesterday came home to a cold house, radiators cold, hot water still working.

Called British Gas under Homecare300 contract and they came out and diagnosed a faulty actuator on the CH zone valve (system has separate valves for CH and HW).

Radiators now heat up but are not as hot as they used to be (only warm really), consequently the temperature is now struggling to reach 18C and the boiler is running constantly. The setting on the boiler (25 year old Ideal Mexico) is the same, i.e. max.

My suspicion is that the new actuator isn't fully opening the valve and restricting the flow to the radiators. Before calling BG back, anyway I can easily test this theory. Or may there be another cause?

Thanks.

TadleyBaggie

Hmmm...not quite as I suspected. The radiators I'd checked (Hall and Lounge) were not very hot, however the radiators in the downstairs WC and study were too hot to touch. The radiators upstairs were also much hotter too.

So I'm now suspecting an unbalanced system. I've restricted the valves on the v. hot radiators and am waiting to see if the cooler radiators warm up a tad.

keystone

Or you've got a blockage. Going back to Post Number 1 you can check the operation of your zone valve by removing the head and observing what it does as somebody operates the roomstat to make the heating come on and go off again. You probably get full travel on the head as its a new one. Next you can operate the valve itself manually. You'll need a tool on the valve spinvdle to give you some leverage. As one face will be flat then an adjustable spenner is fine. If it moves freely you don't have a stuck valve.

I'd fetch 'em back at their cost. They haven't diagnosed this completely.

Cheers

jayyar66

Its unlikely to be unbalanced now, if it was all working well prior to the valve change. Was it the whole valve or just the electrical valve 'head'? If it was the whole valve assembly then its quite likely that air has got in and there's an airlock somewhere. But as Keystone says, get 'em back at their cost, it sounds like it was their doing!