Heating problem

[JonathanTaylor]

Hi, Looking at the manual, I think I have an S plan heating/hot water system.

1. When only the hot water turns on (central heating off, on the programmer/controller), the pump and two Honeywell V4043 valves open and the central heating comes on too. Is this normal for an S plan system?

2. Also, recently, even when the central heating thermostat in the lounge is turned up (flame icon is showing so boiler should be on) the boiler is not kicking in, nor the pump or valves. Is this is a problem with the lounge thermostat or maybe something else? Can I test the stat somehow or is it defo dead - multimeter?

Any help appreciated. I'm moving house in a week's time, and don't want to leave the new people with a problem as Winter kicks in

Jonathan

 

[kevindgas]

unless someone has been fiddling! i would suspect the timeclock is the culprit. the zone valves should open for the selected circuit not both

 

[solman]

are you sure zone valve is opening for heating when on hot water only they can get stuck open but not make the microswitch hence no response from room stat hope this helps

 

[JonathanTaylor]

Hi Kev, No fiddling recently. I replaced the lounge stat (mechanical for digital) and the controller (old one died) over a year ago, but nothing recently.

Hi Solman, I tried turning the hot water on and off and listening for the valves closing when I switched it off. It could be that only one of them is switching off, not the other - but it's hard to tell. I did notice that they both have a small bit of metal sticking out of the bottom of them; on one of them this is quite firm (I think this is the one I can defo hear turning off), but the other one's bit of metal can be moved quite freely - is that maybe a sign of a fault and getting stuck open like you mentioned?

I am also still confused by the heating pump coming on with hot water only switched on on the controller, is that normal though?

 

[solman]

if you can move the metal slider across on both zone valves on hot water only it may indicate a seized vaive or wiring error hope this helps

 

[kevindgas]

theres the problem, go straight to the top of the class
the valve that the lever stays loose is B****ered, the motor is probably cacked these can be replaced simply or the whole valve can be changed

the reason the boiler fires/doesn't fire will be the microswitch in this valve is / isn't making a contact properly

 

[bengasman]

Probably wired up wrong.

 

[JonathanTaylor]

Thanks both, for info and quick replies


Hi Solman: On the valve that I think is making the noise, I can push it across by applying some force, and it makes a noise like a motor being pushed manually, then it self rights itself back to the original position. The lever on the other valve is completely loose, no resistance to pushing at all, no noise when i push it, and it does not try and self-right itself. Does that sound more like a faulty valve than wiring (just want to try and rule out any chance of wiring before changing the valve).

Hi Kev: I'd rather replace the motor than the whole unit if poss - anything to avoid plumbing at this late stage in the house move. Do you think a replacement motor is something I can get from Plumb Centre, and can it be replaced without draining the system?

 

[Agile]

Yes Yes

 

[kevindgas]

yes its easy to do
a Synchron motor is what you need Parts rather than plumb center (usually same building different counter!) or any reputable parts supplier

take silver cover off the motor is held in by a single or 2 small screws, then you twist the motor to release it. you just clip the wires and rejoin with the bits in the box they aren't polarity sensitive so either way will work.

 

[JonathanTaylor]

Thanks all for your help, Parts desk for me tomorrow....

 

[JonathanTaylor]

Well looks like it was the valve - thanks all. I took the front off the silver box and in doing so noticed the manual lever seemed to be working correctly again - must have just needed tapping the motor to free it. That's good enough for me for now.