Worcester Greenstar 18 Boiler Blowing Main 15A Fuse

[LynMc]

Our Greenstar 18 boiler is 18 months old no problems until this weekend (would like to say here we were informed that we would make a saving on our gas bill changing to a condensing boiler from our old Ideal boiler - this has not been the case - have checked our usage we are running at the same amount of units). Came back from being out on Saturday, there were no lights on the programmer nor the boiler - after investigation we found that the main 15A fuse had blown in the garage. The strange thing is that the 13A fuse in the socket switch for the programmer/boiler had not blown. We put a new 15A fuse back in and everything started working and seemed OK, however, on Sunday, same thing the 15A fuse blew again but not the 13A in the socket switch. When we put another fuse in, the boiler fan started up but then cut out and nothing else worked, could this be a pump rather than a boiler problem?We still cannot understand why the main 15A fuse would blow without the smaller 13A going first.

Boiler is under 2 year guarantee but we have to be sure it is the boiler at fault before we call them out or else we get a very high (& extortionate) callout charge apparently

Thanks for any help

Lyn

 

[gas4you]

Firstly the fuse in the switched fuse spur on the wall next to the boiler should be a 3Amp fuse MAX

Is it a Greenstar system boiler, or open vent?

The most common items to blow a fuse are the pump and the fan.

If you can, you need to isolate the boiler from the electrical circuit, either by turning it off, or prefereably removing the wires and then making them safe.

Once this is done, turn the power back on. If the fuse still blows then it is a fault external to the boiler. If it doesn't blow, then it points to a fault somewhere on the boiler.

 

[LynMc]

Thanks for the quick reply Dave

The Corgi Registered Plumber brought his own electrician who wired everything up and he is the one who put in the 13Amp fuse!!!

The system is vented.

Everything was changed - cylinder tank, CH pump and another smaller microswitch or valve item, so everything is only 18 months old.

Will try the isolation 'process' tonight - just got to go and get lots of fuses first!!

Lyn

 

[stem]

Could the cable after the 15A fuse, but before the boiler fuse have been damaged? Any new shelves installed, pictures hung etc., recently!

A 15A fuse in your consumer unit suggests that that part of the installation is quite old. Is it possible that something else has been connected to the 15A fuse? for example a rogue socket in the garage or outside somewhere etc., that is causing the problem.

Do change that 13A for a 3A. Boilers have circuit boards and components that can easily be damaged by too much current. The 3A fuse is designed to blow before they are subject to too much current "frying" them.

It's not unknown for a 15A to blow before a 13A. The stated current rating of a fuse is what it can carry continually without deterioration. Fuses have different caracteristics , but usually take quite a high percentage overload before they blow. One fuse might blow very quickly in the event of a high overload, but handle a relatively small overload for quite some time before blowing. Another might blow more quickly with a small overload.

 

[Agile]

The boiler may be within the warrantee time period.

However, fitting a 13A fuse in the supply to the boiler invalidates the warrantee!

Its most likely to be an external pump though. Disconnect that and I expect it will not blow any fuses.

Some pumps smell burnt if you remove the terminals covers if they have overheated.

Tony

 

[simond]

The boiler has an internal fuse that would have blown in the event of a boiler induced fault.

The installer has made an error with the fusing unless your information is erroneous.

I would call out a Gas Safe registered outfit with a Part P qualification in this instance.

 

[LynMc]

Did all the checks and would seem that neither the boiler nor pump are at fault. The wiring has to be checked (not with the same electrician who put in the wrong fuse - erroneous or not !!!!!!) - taking down part of coving/ceiling along one section to be checked at weekend

Thanks for everyone's help.

Lyn

 

[gas4you]

A qualified sparks will be able to check/test the cable without you removing any ceiling or coving.

He will just need access to both ends of the cable run.

 

[Agile]

Many pump faults do not give any indication with a low voltage test.

An easy way to test is to power the pump from a plug and socket fused at 3A.

Tony