Worcester 24si II – dangerous design or bad install?

[Rob.S]

My hot water ran cold yesterday so I had a look at my 4 year old Worcester combi boiler which appeared to be dead with an electrical burning smell. After checking the fuse etc I took the front off and found this:

http://www.syzygys.f2s.com/boiler/

Basically a pipe had melted through the fan cable insulation and shorted out. Everything looked like it was in the right place since the cable is routed down this side of the boiler. Am I right that it should just be hanging around like this or should it be secured in some way?

The problem blew a fuse on the PCB but luckily there is no other damage, I just need a new piece of cable. I was curious whether anyone else had a similar problem with these boilers though?

 

[croydoncorgi]

That looks like the main supply cable - not 'part of the boiler' at all!

Looks to me like the installer just poked the cable through from the back of the boiler and it was left lying against something hot! Unfortunately, there's no enforced requirement to use heat-resistant cable in this situation....
There should be!

Is all the crud around the nut in the 3rd pic part of the same incident - or has the boiler been having a sly little tiddle as well?

 

[Rob.S]

That looks like the main supply cable - not 'part of the boiler' at all!

Looks to me like the installer just poked the cable through from the back of the boiler and it was left lying against something hot! Unfortunately, there's no enforced requirement to use heat-resistant cable in this situation....
There should be!

Is all the crud around the nut in the 3rd pic part of the same incident - or has the boiler been having a sly little tiddle as well?

It's definitely part of the boiler, the power comes in from the other side. It is shown as the fan power in the service manual and runs from the PCB up to the top of the case. You can see it in the pic below where it also looks like it just hangs around waiting to be melted!
http://www.worcester-bosch.co.uk/index.php?fuseaction=site.viewFile&id=7182

I don't think there is a leak but the stuff on the nut in the 3rd pic is where the insulation had melted and the wire had shorted out.

 

[chrishutt]

Internal cables would be heat resisting and there is no way that a pipe at say 80C could melt through the insulation. I would suspect mechanical abrasion to be the cause. Might the pump have been vibrating abnormally? It's obviously been leaking (as CC pointed out) for a long time - the deposits of concentrated inhibitor (?) might have had an adverse chemical effect on the insulation.

 

[Rob.S]

Internal cables would be heat resisting and there is no way that a pipe at say 80C could melt through the insulation. I would suspect mechanical abrasion to be the cause. Might the pump have been vibrating abnormally? It's obviously been leaking (as CC pointed out) for a long time - the deposits of concentrated inhibitor (?) might have had an adverse chemical effect on the insulation.

Yes I think you might be on to something with the inhibitor corroding the insulation. It was only resting on the nut and not taut so I don’t think abrasion would be the cause.

So I guess my next question is if that if a joint like that is leaking is it just a case of trying to tighten it up or should I get a plumber to come and sort it out?

 

[james12]

I put this in the wrong place. Sorry. I've now started a new topic.