Combi boiler electrical supply

[NickB_99]

Hi,

My combi boiler has a switch to isolate the power from it, but it has no fuse.
The boiler manual says there should be a 3a fuse protecting the supply.

I want to put in a wireless thermostat and I have it ready, but I am wary of wiring it in and damaging £100 of thermostat.

Is this normal to have no fuse in the switch?
Or would you advise swapping the switch for one with a 3a fuse installed before connecting in the thermostat?

 

[Galoka]

Yes, the combi should be connected to a Fused Connection Unit (FCU) fitted with a 3A fuse. It is an easy enough to swap the existing switch for one.

This kind of thing: http://www.screwfix.com/p/mk-13a-dp-switched-fused-connection-unit-with-flex-outlet-white/13479

Though, it won't make any difference as too whether you blow up your thermostat Before you wire it in, have a good read of the instructions, make sure understand the current setup and what you need to do before you start)

(As an aside, the fuse - like a fuse in a plug, is there to protect the cable from the FCU to the boiler, in case of a fault condition which would overload the cable and cause it to overheat)

 

[Burnerman]

Always a good move, I think, to have the boiler on a low current fused supply.....if something does go haywire within then you get maximum protection - but there may be other fuses on the PCB of course.
Its a simple enough job to change your switch for a fused spur - the chances are the metal box will be deep enough for a two pole item.
This won't necessarily protect your new thermostat though, and there should be guidance regarding fitting that in the installers instructions......often enough the stat connects directly onto the PCB.
John

 

[NickB_99]

Yes, the combi should be connected to a Fused Connection Unit (FCU) fitted with a 3A fuse. It is an easy enough to swap the existing switch for one.

Ok, will go for that. Screw fix is up the road and usually go there - so thanks for the link, saves wading through the large numbers of them!

Before you wire it in, have a good read of the instructions, make sure understand the current setup and what you need to do before you start)

Have had a good read and think I've worked it out. But will check, may post some pics on a separate thread tonight. Best be safe!

 

[NickB_99]

Always a good move, I think, to have the boiler on a low current fused supply.....if something does go haywire within then you get maximum protection - but there may be other fuses on the PCB of course.
Its a simple enough job to change your switch for a fused spur - the chances are the metal box will be deep enough for a two pole item.
This won't necessarily protect your new thermostat though, and there should be guidance regarding fitting that in the installers instructions......often enough the stat connects directly onto the PCB.
John

Had the switch off tonight, the box is deep.

I will post pics later this eve and ask for advice to make sure.