Cylinder stat controlling central heating - Is this correct?

[fishface]

Hi all,

I've just moved in to a new house and am trying to work out the heating system, which seems a little eratic. My old place had a combi boiler and the new place has a fully pumped system.

I get periods where the the CH and hot water timers are ON and the room thermostat is high enough to create a demand, but the CH does not seem to work. I played around a little and removing the cylinder stat from the side of the cylinder and allowing it to cool starts the CH system. (pressing the metallic strip then stops the CH pumping).

This seems strange to me. Can anyone explain why the cylinder stat should control the CH system pumping water through the radiators? I always thought that this was controlled only by the CH timer being on and the room thermostat being set higher than the room temp. Is this a sign that the set-up has been plumbed incorrectly?

Thanks

fishface

 

[secret squirrel]

It shouldn't (obviously), have you got 2 x 2 port valves or 1 x 3 port valve?

When you turn the hot water on, do the rads get hot?

It sounds possibly that you have a knackered valve. That is providing it was working correctly before.

 

[fishface]

How do I tell if it's a 2x2 or 1x3 please? The valve is a silver box above a T junction of pipes.

I just tested to see if the rads get hot when I turn the hot tap on and they don't seem to be getting hot.

One additional point I remembered is that when the heating is on (i.e. the cylinder stat is 'cold') then I can still turn off the heating using the room stat, by decreasing it's set-point. Not sure if that is relevant, but thought I would mention.

As a temporary measure would there be an issue if I remove the cylinder stat until I get the problem fixed? That way the heating can run as it needs to. I understand the hot water will likely be very hot but is there any harmful effect to leaving it disconnected till it's all fixed? I guess it will just get as hot as the boiler setting, but that there should be no other effect - is that right?