Boiler Blowing Fuses?

[marcus]

Hello,

Our boiler and the related thermostat are powered via a switch which has a 3 amp fuse. Lately we have had a few (three in the last two weeks) power cuts and on a couple of occasions this has blown the fuse for the boiler that is in this switch.

Tonight, when I replaced the fuse the boiler worked for about an hour and then another fuse was blown in the switch. There was no power cut on this occasion - at least not that we noticed.

Prior to this the boiler and the associated electrics have worked fine with no problems since they were installed about 4.5 years ago.

Could there any other reason why the boiler is suddenly blowing fuses in this switch other the the power fluctuations we have been having recently? I presume that the low amperage of the fuse is to protect the boiler circuitry (it is an Icos boiler), but is the problem related to the low amp fuse? I presume we would want to change it due to possible risk to the boiler?

Any help anyone can give would be greatly appreciated.

Thanks,

Marcus

[David Hansen]

On Mon, 16 Jul 2007 21:42:08 -0000 someone who may be [e-mail] wrote this:-

Yes, the obvious one. The boiler, or the wiring associated with it, probably has an intermittent fault. The fuse is reducing the chances that someone in the house is electrocuted as a result. Check the boiler, or get it checked.

[:Jerry:]

The light bulb was OK the last time I switched it on.......

As the other posters have said, it's highly likely that a fault has developed within the boiler or associated wiring, what has caused this will need to be investigated - it's possible that a voltage spike (due to the power cuts) has damaged something or, more likely, the two events are just coincidental.

What ever you do don't be tempted to put in a higher rated fuse (or indeed bridge the fuse out), doing so could be lethal for someone.

[Roger Mills]

What else runs off this fuse? Does it power all the controls for your CH system - including thermostats, motorised valve(s), pump, etc.? If so, the fault could be in any of those components, not necessarily in the boiler itself. I would put my money on there being an intermittent earth leak in the pump. I doubt whether the problem is directly related to the power cuts.

[John Rumm]

Indeed, or it could even be furry critters nibbling on your cables... (DAMHIK!)

[John Stumbles]

I think that may be your problem. I have a friend who has an Isar (combi version) which developed a PCB fault which resulted in it blowing supply fuses.

Please let us know if this does turn out to be the problem.

[marcus]

Thanks to you and all the other replies.

In fact the boiler lost power completely today so I have arranged for someone to come in and look at it.

The switch controls all of the central heating circuit systems (pump, thermostat, timer etc). I never planned to use a higher rated fuse - just wanted to know what could be causing the blown fuses.

Now that the boiler is not getting any power all (but the rest of the CH system is getting power so the current 3 amp fuse has not blown this time) is the consensus that there is probably some kind of fault in the boiler itself? Or is it possible that one of the other potential causes (I think someone mentioned an earth leak in the pump for example) has caused some kind of circuitry in the boiler to blow?

I ask only because I would like to have some idea what the potential problem might be before the professional comes in so that I don't end up being ripped off!

Thanks again for the help.

Marcus

[Lurch]

On Tue, 17 Jul 2007 21:20:52 -0000, [e-mail] mused:

When you say 'rest of the system' I take it it isn't just a boiler and thermostat but a complete central heating control system with valves and pumps?