I've just had my boiler replaced with an Icos HE18. However, since it was installed 10 days ago it works normally for a while, then for no obvious reasons fires up even thought the timer is set for it to be off and the lights showing active CH or HW are off. Most times I can turn it off by lowering the setting on the thermostat but sometimes that doesn’t work either - maybe its trying to heat the hot water but I'm not sure. It tends to work fine for a day or so then does this in the middle of the night. The installer cannot find anything wrong and replaced the timer but it still goes wrong. If the timer is physically removed and left aside for about half an hour it all goes back to normal. We never had that problem with the 23 year old Baxi boiler.
Boiler fires up but timer is off
- Thread starter raybarclay
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Hi Ray
I had a similar, maybe not identical, problem. What I found was that one of the motorised valves diverting heating to CW or HW was seized. The manufactures wiring diagram showed that if this was the situation then the heating boiler would fire up irrespective of the timer control output.
Seemed a crazy way to wire anything up but that is how the manufacturer detailed it. As the whole system was over ridded then the hot water just got hotter and hotter, leading in my book to a dangerous situation.
I changed out the seized diverter valve - job done and no further problems.
Hope this helps.
I had a similar, maybe not identical, problem. What I found was that one of the motorised valves diverting heating to CW or HW was seized. The manufactures wiring diagram showed that if this was the situation then the heating boiler would fire up irrespective of the timer control output.
Seemed a crazy way to wire anything up but that is how the manufacturer detailed it. As the whole system was over ridded then the hot water just got hotter and hotter, leading in my book to a dangerous situation.
I changed out the seized diverter valve - job done and no further problems.
Hope this helps.
the answer is ever so simple. if it was just installed, get the installer back to fix it. if you are not satisfied, call corgi and tell them that you doubt the boiler is installed correctly as it comes on when the timer is turned off. boilers that come on when they should be off, are a potential danger. make sure you have got the installers gorgi number handy.
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Firstly these boilers are designed to fire up every 24hrs on their own to stop the pump sticking etc. This is the same whether it is a system boiler or open vent.
It could well be that you have a faulty microswitch in the 3 way or one of the 2 port valves fitted.
What gets hot if any thing when the boiler fires?
It sounds as though your installer is trying to be helpful but at present just cannot find the fault.
Get him to check that he or the electrician, has removed the link between terminals 1 & 2 on the boiler plug (that slots in under ther boiler).
You need to have the wiring center cover off when this fault happens so the volatage path causing it to fire can be determined with a multi meter.
It could well be that you have a faulty microswitch in the 3 way or one of the 2 port valves fitted.
What gets hot if any thing when the boiler fires?
It sounds as though your installer is trying to be helpful but at present just cannot find the fault.
Get him to check that he or the electrician, has removed the link between terminals 1 & 2 on the boiler plug (that slots in under ther boiler).
You need to have the wiring center cover off when this fault happens so the volatage path causing it to fire can be determined with a multi meter.
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