Blimey, these things always happen over a cold weekend, don't they?
Are the heads to Honeywell 3-port valves interchangeable? I know they are removable, mostly, but is a new one the same as one from 1985 (I guess)?
My tenant called to say the heating wasn't working and I've just been over to try to see if I can work out what's wrong. The hot water seemed to be on all the time and the central heating only coming on intermittently. Obviously I need to get this fixed sharp-ish (they have small children, as we do).
It's just a "y plan" system. House built in 1985, not quite big enough for multiple heating zones. It's an open vent system with a boiler and timer-controller in the kitchen, and pump/valve/junction box all in the airing cupboard with the cylinder.
One question: does the manual override lever on a mid-position valve do anything? The lever on this valve is permanently loose whether the heating/water are on/off. On a 2-way valve (as I have at home here) I know I can energise the valves with the lever.
I'm not entirely sure that I could detect the valve energising or doing anything when fiddling with the heating controls.
Is it a typical fault for the valve to get stuck and fail to operate the heating? If the motor fails, the valve sticks in the water only mode, or the heating only mode?
After kicking the motorised valve and switching the hot water permanently off at the timer-controller, the heating circuit appeaered to come on and the water circuit appeared to start cooling down - but it seemed to take a long time for heat to get to the radiators and by the time I had to leave again, only the upstairs was getting warm. The tenant had bled all the radiators and the result was horribly black, so think I shall have to get someone in to give the whole thing a proper flush.
Michael