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Topic Title: Main Bonding
Topic Summary: Central heating boiler is in an external building
Created On: 26 July 2013 04:59 PM
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 26 July 2013 04:59 PM
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circle143

Posts: 213
Joined: 19 July 2007

Hello,

I was having a brief look over a job today and the boiler for the central heating is an out building about 15mtrs from the main house.

The water supply into the house is in plastic and then goes to copper (no visible bond). However, it appears all of the central heating system is in copper pipe which goes underground to the outhouse - I didn't have time to investigate to see if this is bonded.

Im just wondering if this is something that it overlooked at times - incoming supply in plastic but then rerouted underground etc without further thought ?
 26 July 2013 05:21 PM
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geoffsd

Posts: 332
Joined: 15 June 2010

All extraneous-conductive-parts must be (main) bonded.

This includes central heating.
 28 July 2013 02:10 PM
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circle143

Posts: 213
Joined: 19 July 2007

Indeed.

But in this particular instance - the point of entry into the house is at the copper tail - coming out of the cement floor - to the first radiator
 28 July 2013 02:31 PM
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leckie

Posts: 1768
Joined: 21 November 2008

So bond it at that point then, or at the nearest practicable point after entry.
 29 July 2013 10:58 AM
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AJJewsbury

Posts: 11349
Joined: 13 August 2003

Are the copper heating pipes actually in contact with the soil? It feels unlikely to me - just from the point of view of thermal performance - you'd loose so much heat into the ground over 15m (x2), I'd expect (a lot) of thermal insulation surrounding them - which is likely non-conductive. If it's a fairly modern system I'd be surprised if they're even copper underground (it's so much easier to lay plastic in trenches, no joints buried and so on).

- Andy.
 29 July 2013 11:08 AM
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leckie

Posts: 1768
Joined: 21 November 2008

What about if the remote boiler is bolted/fixed to concrete, wall, etc. might be earthy. Obviously wouldnt matter if it was in plastic, but I wired in a couple of large remote TPN ASHP's that were fed in about 50mm copper pipes wrapped in insulation that was about 150mm diameter. I bonded where the pipes entered the plant room. They were bolted onto concrete bases that sat straight on the soil. It's a bit difficult to test as extraneous parts because of cpc's etc.
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