Heating on when timer off?

[SyncroMan]

Up till now my heating has been working fine, on/off with timer, room-stat and tank-stat etc. The other day the central heating mcb tripped and after resetting the heating is constantly on even when the timer says off. Lowering the room-stat temp does still turn the heating off.

Has anyone had this situation before, and is it most likely a timer problem?

Any suggestions would be appreciated.

Cheers

 

[marcusone]

If roomstat will shut heating off then its the timer.

Sent from my HTC One X using Tapatalk 2

 

[ringer]

Yes, is most likely the timer. If you can get the same make/model then it can most likely be fitted without having to touch any wiring - they usually plug in to a backplate, and the wiring is terminated to the backplate. Just turn off the mcb before you look at replacing the timer.

 

[Darkwood]

It sounds like you had a short circuit thats cleared itself but in doing so it welded the contacts in timer permanently closed... the mcb tripped for a reason just replacing the timer may cost you again if it re-occurs until you know what was the cause of the tripping id be weary of just replacing it and forgetting about it.

 

[tamz]

Its a motorised valve

NOT.

Reading the post correctly would help.
If the stat is turning it off then it is the timer.

 

[fog]

Agree with Darkwood, what is causing, worth checking.
Had similar problem, changed timer only to burn new one out expensive, 2 valves is s plan, 1 valve is y plan, the way i tested eventually which is good tip, to prevent from blowing new timer is to link the hot water on terminal to permenant live, then turn on and off by switch fuse, then do same for central heating on terminal, on and off by switch fuse making certain you have correct fuse 3 amp gas 5 amp oil, if this works ok atleast you have proved the motorised valves are ok (i had a burnt out motorised valve which then burnt out 2 timers expensive) once you have proved the motorised valves you can then connect your new timer, the only other components are the cyclinder stat and the room stat, WHICH do go wrong albeit very rarely, also check the ten block connector these are prone to welding wires together if a component goes wrong as the wires are so close together. hope this helps

 

[fog]

Remember my post above is only a temporary fix do not run permantly with linked wires to permanant live. Thought would state that in case someone thinks thats a permanant fix .DO NOT LEAVE AS ABOVE ONLY FOR FAULT FINDING

 

[Darkwood]

Its a motorised valve

Is this a question, statement etc is it direct to OP's query or following my last post .... punctuation carries alot of weight as to your intended message!, also if you are just throwing a guess into the thread explain your reasoning for your view this will aid the OP and also may help others agree or disagree with your views.

P.S. Welcome to the forum.

 

[fog]

Of course my previous post didnt enlighten a problem with boiler as i presumed this is ok, if its working for hot water it must be external to this for the central heating not to work correctly, as the boiler doe not know if its heating up hot water or central heating its the valves that do this via the stats and timer/programmer

 

[tamz]

Is this a question, statement etc is it direct to OP's query or following my last post .... punctuation carries alot of weight as to your intended message!, also if you are just throwing a guess into the thread explain your reasoning for your view this will aid the OP and also may help others agree or disagree with your views.

P.S. Welcome to the forum.

Just a passing browse. Reading the post correctly helps of course.
If the stat wasn't turning off the heating (or boiler) it (as i'm sure you will know) is being fed from the microswitch on a valve. It could also, depending on the boiler, be feeding from there.
But it is not.

Thanks for the welcome.
Tam
(Poor plumber with hopefully only another 10 or so years more left doing this garbage)

 

[fog]

We like plumbers very good wit tamz, never heard of a poor plumber though!! ho ho

 

[tamz]

never heard of a poor plumber though!! ho ho

A bit of an urban myth but nearer the truth than we are all on 60k+

 

[mountainman]

We like plumbers very good wit tamz, never heard of a poor plumber though!! ho ho

Could say the same about sparks too!

 

[SyncroMan]

Agree with Darkwood, what is causing, worth checking.
Had similar problem, changed timer only to burn new one out expensive, 2 valves is s plan, 1 valve is y plan, the way i tested eventually which is good tip, to prevent from blowing new timer is to link the hot water on terminal to permenant live, then turn on and off by switch fuse, then do same for central heating on terminal, on and off by switch fuse making certain you have correct fuse 3 amp gas 5 amp oil, if this works ok atleast you have proved the motorised valves are ok (i had a burnt out motorised valve which then burnt out 2 timers expensive) once you have proved the motorised valves you can then connect your new timer, the only other components are the cyclinder stat and the room stat, WHICH do go wrong albeit very rarely, also check the ten block connector these are prone to welding wires together if a component goes wrong as the wires are so close together. hope this helps

Thanks for all the responses.

Before I buy a new timer, All house wiring is new and i have checked all the terminals are secure, the three way motorized valve is new and appears to be working fine i.e. goes to heating, water and mid-position. Hot water side of timer works fine, timer turns it on/off and tank-stat does the same. Boiler coming on and off as it should. When heating is in off position the pump and boiler still fire up when room-stat is high enough. The tank-stat is old but works fine, the timer is a Grasslin QE2 which is about 8 years old, and the room-stat is a tower rs and is about 8 years old.

Can a faulty timer cause the mcb to trip, or is it more likely to be another problem? Its worked fine for the last three months.

 

[oldtimer]

Why dont you turn up your room stat so it call for heating and when it does then remove the timeclock from its backplate heating goes off its the timer