Why does my central heating valve click and remain open all the time?

[Darlajane]

Hi!

I recently got rid of my analogue central heating and hot water timer and replaced it with a nice digital one.  However, now whenever I put the hot water on alone the central heating comes on too.  I discovered that the valve isn't working properly and it mustn't be able to shut itself.  It moves a little and then clicks every couple of seconds as if it can't get any further.  I've fiddle with it, added some WD40 and nothing has changed.

Do you think I need a new motor or is there something I've missed?  The make of valve is Honeywell V4043A.

[Darlajane]

 Sorry I meant it was a Honeywell 4073A valve!

[BillyNoMates]

Are you sure the wiring to the 3 way valve is correct ? For example, it may be reversed and trying to open more rather than close when the HW comes on.

Are you able to manually lock the valve into position ? - some have a manual lever with a latching mechanism.

I'm not familiar with that particular valve. Sounds like it is trying to work but may be sticking or have dirt/debris inside preventing it from fully closing or just worn.

Was is working OK beforehand ? If so, I'd look at the wiring first.

[Darlajane]

I see what you mean with getting the wiring the wrong way round.  I assume that would happen if the neutral and live were connected back to front?  I have checked the wiring many times but I will have a look again just incase.  How do I fixed it if the motor is trying to go the wrong way?

However, even if it is trying to go the wrong way it's clicking as if it's stuck some how after moving some distance, rather than just opening instead of closing.   I've tried tracking which way it's trying to move and it does seem to be trying to open the valve rather than closing it.  It was working find until I rewired the timer.

If I manually open the valve it switches back to open again as soon as I turn the power back on.

Oh the joys of home DIY....

[lembo121]

Hi, first of all the wiring to the programmer is not directly linked to the moterised valve, therefore the replacement unit has nothing to do with the "clicking". The moter is slipping from the leaver arm hence the noise! You need to replace the valve! Is the valve internal, or, external to the boiler? This fault is comon on Potterton boilers and you might be able to replace the head only.

[KARL]

Power from the mains comes to the timer direct, then the timer distributes power to the "zones" as per desired timings for attention from the pump and boiler. Each zone is usually governed by a thermostat which must ask for heat by closing its switch (e.g click on turning up or as temperature drops below desired level), thus sending power to the zone valve which once open by motor action triggers its internal switch to provide power to the pump and boiler (if no thermostat then you have no control based on temperature, just "burn baby burn"). The wiring thus in effect goes mains-timer-thermostat-valve. The internal switch in the valve is often/usually powered direct so once closed the pump and boiler are energised. There is a separate thermostat within the boiler to switch the gas off to ensure the circulating fluid does not overheat. Precisely what your problem is is rather difficult to say for certain, but the actuator head (the electrical bit) is a likely suspect. Not all Honeywell valves have easily replaceable heads so if it is faulty you may need a new valve - but diagnosis on site is the answer. Unfortunately not all tradesmen are fully competent, reliable and honest so you are best to engage someone with a good record, especially if you live in a large city.

[Darlajane]

It is possible to replace the motor without removing the valve and the valve is right next to the cylinder and not in the boiler so it's easy to get to.

Does this mean that I only need to replace the motor?  Does anyone know of a decent electrician who could do this for me in the Coventry area?

[Redandy2]

The ports are labelled A, B, AB, stamped into the body of the valve casting.

AB is supply from the boiler, A goes to central heating and B goes to hot water i e the cylinder.