Plenty of hot water but radiators and boiler keep going off

[ightenhill]

I'll try to explain this as best I can.. One morning when we awoke we had hot water as usual but the radiators had not come on. No amount of jiggling the thermostat or the central heating switch made them come on. I looked in the Immersion cupboard and noticed a switch that was sticken out of a white box called a MID POSITION VALVE that I had never noticed before and the switch seemed to be baggy and hanging. I psushed it and it seemed to click into position and an indicator on top of this box moved from W to M and the pump started working and the radiators started to come on.

Phew its fixed I thought, but now all that seems to happen is the radiators stay on for about 3 hours or so and then go off. Oddly they come back on if we run the hot water and I notice that that indicator never moves to H on the white box(though I dont know if it should). Also a couple of radiators in the furthest reaches of the house dont seem to be getting any heat at all though they were fine before.

Im guessing into thin air but it seems my radiators only work when the waters being heated for the tank and once thats hot maybe this valve should move to H to supply the radiators but is stuck.. Am I correct, is it easy to replace, or am I barking up the wrong tree.

Thanks

Danny

 

[ChrisR]

Motorised valve would seem to be faulty. Cure depends on make and exact fault.

 

[ightenhill]

its an acl lifestyle mid postion valve h340-30l0 have not seen it in any poswition but M.. wont move to H even manually , it swings to H for a second(and the pump fires up) when you push the manual lever but immediatly goes back to M

 

[kirkgas]

you will need to change the valve head at least, the valve itself might be jammed but is is usually the head that is faulty, when you moved it manually it worked because the water going to the hot water cylinder was going to the rads as well that is why it stops after 3 hours because the cylinder is satisfied (ie full of hot water) and why the rads heat when you run hot water because the cylinder is cooler and bringing the boiler back on again.
have you checkerd there is power getting to the valve from the heating side, it could be a faulty room 'stat or timer.

 

[ightenhill]

Ok tried to explain this to first plumber who said he would have to drain system and replace the entire valve and its pipework. Told him I would ring him back. Called another plumber who said to try replacing the motor first on the midposition valve as these tend to fail. he sold me one for £15.00 and I fitted it myself. Problem solved.

 

[seco services]

had one exact same prob yesterday paddle seized in valve solid.
fitted complete new valve as the early ones didn't have removable heads.