Potterton Netaheat short circuiting?

[uphoriak]

Hi guys, first post an' all after searching google so "hello"

My problem is similar to Joe's at //www.diynot.com/forums/viewtopic.php?t=64659

I've got a Potterton Netaheat electronic 10-16 boilder with an Ep3000 electronic control box and a PWB1 circuit box, and on sunday the 15A fuse in the main house electricty control box blew.

After replacing the old fuse-wire type MCB with a tripswitch MCB type box so I can properly test things out I'm finding that if I turn the CH on via the control box absolutely nothing happens, and if I turn the HW on to 24 hours (to test it), the control box will either make repetitive ticking sounds (and the indicator light for HW flickers on and off), or it will work for a random length of time and then the trip switch on the fuse box will go. Last night it worked for a few hours, this morning for about 40 minutes, and this evening for about an hour. Then the fuse box trips, and everything obviously shuts down.

I'm guessing there's either a short circuit in the control box, or after reading Joe's thread I'm guessing it could be a pump problem? After switching off the electricity supply to the house I opened the face plate of the circuit box but none of the wires were loose from what I could gather.

I'll admit I know next to nothing about this stuff and I've got a guy coming round tomorrow night to have a look at it, but any advice anyone could give me in the meantime would be much appreciated. Thanks

 

[gas4you]

Why did it blow the 15amp? where is your 3 amp switched fuse to protect boiler/heating system circuits?

 

[uphoriak]

Why did it blow the 15amp? where is your 3 amp switched fuse to protect boiler/heating system circuits?

No idea why the 15amp blew - the 3amp switched fuse was/is fine and is right next to the control box.

 

[Trance Nation]

A very similar fault i seen recently was a faulty zone valve motor on c/h that was pretty much burnt out. The system would fire up for around 10-15 mins before tripping the fuse box. I just went round the components one by one and disconnected/looped out till i found said problem - The engineer who's coming round will do some similar checks i imagine. Shouldnt be a tough one to fix.

 

[uphoriak]

A very similar fault i seen recently was a faulty zone valve motor on c/h that was pretty much burnt out. The system would fire up for around 10-15 mins before tripping the fuse box. I just went round the components one by one and disconnected/looped out till i found said problem - The engineer who's coming round will do some similar checks i imagine. Shouldnt be a tough one to fix.

Thanks for the heads up. The pump seems fine so it's not that, and similar to what you say I think I've traced it down to when the CH temp. reaches the setting on the thermostat for room temp, seems to be this that's tripping the box.

I'll post more when I get to the bottom of it

Nice handle btw!

 

[pannierstan]

Is it possible that the roomstat has gone kaput as they have(or should have) a neutral and I have had that cause a trip.

Still doesnt answer the question about the 3 amp fused spur though??

Stan

 

[uphoriak]

Another day, another new development!

Got home from work today, set the 15A tripswitch MCB downstairs in the fuse box to on... and it clicked straight back off again. The switched 3A fuse isn't even switch on, the control box didn't have power going to it, the CH and HW wasn't on or anything, it just tripped immediately.

So, I'm now guessing the immersion system could possibly be connected directly off the 15A circuit rather than the 3A spur (which if is the case I don't even wanna consider), and that the immersion element is shot.

So now I'm phoning round friends getting recommendations for electricians in milton keynes to come out and have a look.

Having never had to deal with anything like this before lets just say I'm learning a lot, and pretty fast. It's starting to wear my patience now having it going on for almost a week, but there you go.. it's all part of being a first time homeowner I suppose!

 

[gas4you]

The 15A circuit is for the immersion heater. The 3A fused spur is just for heating. Immersion won't work on 3amp. This explains why the 3A didn't blow

 

[uphoriak]

The 15A circuit is for the immersion heater. The 3A fused spur is just for heating. Immersion won't work on 3amp. This explains why the 3A didn't blow

OK, thanks for clearing that up, I did say I'm learning everything from a standing start, it's just one of the people I spoke to on the phone said "well the immersion could run off the 15A" so I surmised it therefore could not run off it.