motorised valve query

[MP]

Hi All

I've just had a check done by a CH engineer who thinks (not sure) that my motorised valve is set up wring, in terms of the ports.

At present : A goes down through the floor AB connects to the pump (then goes into the loft, where there is a wierd t-port device which then goes back down through the floorboards) - assumed to be source from boiler B goes to the hot water cylinder

So, what he says is the problem is that when the heating is on so too is the hot water, which cannot switchitself off (thermo stat bypassed in favour of central heating thermostat).

I must admit to having installed this MV myself but only after going to a local plumber merchant and asking for like-to-like mv replacement.

Any comments.

Thanks

Matt

[Andrew Gabriel]

It is more usual to have A (resting position) going to the hot water cylinder, and B going to the central heating, at least if you use any of the convensional circuit arrangements.

Of course, you can design a circuit to operate it some other way (I have A doing downstairs heating, B doing upstairs heating, and a control box with 4 relays in it).

[Set Square]

Assuming it's a 3-port mid position valve, it sounds *more or less* ok. AB is the inlet - so hot water comes into the valve from the boiler via the pump. A is the CH outlet - so the pipe which goes down through the floor probably feeds all the radiators. B is the HW outlet, and rightly goes to the HW cylinder.

I'm not quite sure what you mean about the pipe going into the loft - or about the "wierd t-port device". Is it a vented system, or is it unvented/pressurised?

Any chance you could take some digital photos of the valve and of the thing in the attic, and upload them to the internet somewhere and post the URL here?

What exactly are the symptoms you are experiencing?

[Set Square]

Does it depend on the make of valve? My Danfoss valve *definitely* says A=Heating and B=Hot Water. That's the way it's connected, and it works as expected. My valve's unpowered resting position is with B connected to the input.