Hot rads when they should be cold.

[petebdsppl]

My central heating/hot water system has become very unpredictable and temperamental. I have a new baxi condensing boiler, motorised pump,hot water tank and I presume an open vented system. All the radiators have a habit of heating up when the water should be heating up for the hot water tank. This doesn`t happen all the time but I`ve noticed that it tends to happen after the central heating has been on. I have set my timer so that the central heating and water heating functions are at different times of the day and not on together but the problem still occurs. The timer is set to fire the boiler up for hot water first thing in the morning but quite often all that happens is that the rads get really hot throughout the house.I can sometimes correct this by switching the timer off and on again and this seems to reset it until the next time.Please help!!

 

[ChrisR]

Typical plumber's wiring perhaps.
I expect you have a 3 port valve, and if you remove the front from your programmer you will find no wire on the HW OFF terminal.
See the wiring diagram (nb pump wiring may be different)

 

[pannierstan]

Im not sure I agree with that Chris.

If there was no off live from the programmer then that just means you wont get heating without the programmer being on for dhw.

I would say that either the valve is passing or there is indeed a wiring fault but certainly not on the dhw off live.

Stan

 

[petebdsppl]

Thanks to ChrisR and pannierstan for their advice and quick replies. It is possible that the programmer was not wired in correctly after having my new boiler installed a few months ago. The electrician did make some comment about the wiring being somewhat unusual and said that he would just copy how it was wired up previously. I shall get someone out to look at it to see if it is a problem with the wiring. One point that still confuses me however is that the fault doesn`t occur all the time. For instance, today everything has worked fine with the rads heating up when they are supposed to and remaining cold whilst the dhw has been heating.Whereas yesterday evening the rads heated up when the dhw was supposed to be on. Not being too technically minded, can this be explained by a wiring fault or could there be a problem with my 3 way valve.

 

[pannierstan]

I mentioned it could be the valve passing then.

Stan

 

[Agile]

Some wiring faults can produce a situation where the last heat requirement has an effect on the next!