Fuse Blowing on Maxistor Horstmann Electronic 7

[Kimberley88]

Help appreciated for this problem please, my neighbour told me she had no hot water, she has a Hortsmann Electronic 7 maxistore timer/controller, I found the fuse had blown on fused spur, so I replaced fuse and as soon as Boost is pressed on the box it blows the fuse.

My first thoughts are the element on the emersion is to blame, can someone advise how I check this so I can eliminate it or prove its the problem.

Thank you.

 

[ollski]

Not sure on the setup but I wouldn't think the immersion was linked in to the programmer (though its possible). Almost always the pump or fan on the boiler and sometimes a leak on to electrical components.

 

[chrishutt]

I presume this is an economy 7 set up with two immersion heaters in large cylinder. The boost switches the upper immersion heater, so this is probably leaking to earth. If you isolate it electrically, you can test with a multimeter the resistance between the current conductors and earth.

Resistance should be approaching infinity, so if you get a lowish reading it shows leakage. Someone will doubtless know the resistance figures to look for - I think they were posted very recently. Most likely you'll find that the heating elements have split open to expose the live conductor to water, although it could be something simpler like a wiring fault.

 

[ollski]

sorry, of course didn't click the relevance of 7 in the name

 

[Kimberley88]

Thanks for your replies, I forgot to say it was economy 7 and a strange layout, it appears to have an immersion heater then what looks like another immersion on top. But it only has one cable that goes from the element into the programmer. I checked to see that no cables had come loose. I will check the resistance tomorrow.

I suggested that the neighbour come round and take a bath here but as she is a rather attractive blonde my wife was not keen on the idea.