Motorised valves

npm1971

Hello!

Wonder if anyone can help with a central heating query? I have a gas condensing boiler with water tanks in the loft and a hot water cylinder in the airing cupboard. I have a little wireless heating control in the hallway which I use to raise the required temperature and start the central heating. When I start the central heating, a flame indicator appears in the wireless control box to indicate the heating is on and the wireless receiver in the airing cupboard indicates that the signal has been received.

However, the boiler doesn't fire up every time. Sometimes it works,sometimes it doesn't. When it doesn't, I can get it to work by moving the handle on the motorised valve a few times (it is quite stiff). This suggests to me that the problem is that the valve is seizing up? (I have two such 2-way valves - presumably one for the central heating and one for the hot water tank). Does that sound correct and, if so, do I need to replace the entire unit?

Another question out of interest - how does the opening/closing of that valve cause the boiler to fire up (or not) - is it an electrical signal from the unit to the boiler?

Hope I've explained that correctly! Many thanks for any replies.

a&akay

I installed 4 zone valves on my system, one to our upstairs CH zone, one to our downstairs CH zone, one to our independent granny flat CH zone (she likes it hot!) and one on the hot water tank for her and our hot water from the shared hot water tank. Our upstairs and downstairs zones both failed separately on the respective zone valve seizing open, not shut as you report. One required a new zone valve, the other a serious dose of WD40 to free it up a couple of years ago, but it still works OK. These zone valves call for boiler heat on being opened by a heating demand signal eg from a timer, thermostat or both (in a combined unit). If they seize open the boiler fires 24/7. Yours sounds like a seizure on failing to open if you can solve the problem by opening the valve manually? Try the WD40 route.

Owain_Moneysaver

The thermostat sends a signal to the valve motor, this operates the valve and an actuating lever operates a microswitch which then sends a call for heat signal to the boiler.

You may only need to adjust or replace the microswitch, or the actuator head, which in most cases can be done without removing the valve body (the wet side) from the pipework.

http://www.diyfixit.co.uk/central-heating/motorised-valves-replacing-actuator-or-valve.html

npm1971

Thanks for the responses. Really useful to understand how these things work. Had always thought that the programmer somehow fires up the boiler but of course now realise it doesn't!

EssexExile

If the programmer thinks it's time for heat, the thermostat thinks it's cold enough for heat & the valve is in the right position for heat - then the boiler will come on. Any one of those missing & it won't won't. Of course nowadays all the electronic wizardry has to be in the right mood too or nothing will happen!

C_Mababejive

What make/model is stamped on the vale? are they industry standard silver/metallic honeywell V4043H ?