That's correct
The forth wire on a Ideal Logic 18kw Heat Only System Boiler
- Thread starter Ray1000
- Start date
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I understand Ian, I was discounting earth wires and assuming it would be OK to get the second live from the fuse spur outlet making 2 in and 3 out.
Please correct me if I'm wrong, but ...
Where I made my mistake 30 years ago was having LNE from the consumer unit and then LNE out from the fused spur but with the live only going as far as the programmer half way up the wall. The neutral and earth continued to the wiring centre in the loft but the live only got there as a switched live ... I think.
At the time there was no need of an un-switched live in the wiring centre it wouldn't have been used until 3 years ago when the boiler now needed an un-switched live.
Ray
Please correct me if I'm wrong, but ...
Where I made my mistake 30 years ago was having LNE from the consumer unit and then LNE out from the fused spur but with the live only going as far as the programmer half way up the wall. The neutral and earth continued to the wiring centre in the loft but the live only got there as a switched live ... I think.
At the time there was no need of an un-switched live in the wiring centre it wouldn't have been used until 3 years ago when the boiler now needed an un-switched live.
Ray
That's correct
I don't see what the problem is. From your layout sketch the fused spur is local to the boiler, so should be able to run a wire between them. You wouldn't normally use a single-core length of wire, it would look a bit messy, but from any of the junction boxes or terminal strips which has a permanent live. If it's currently a 3-core to the boiler you could change to 4-core for a neater job.
No the fused spur is simply an isolating switch nothing else, just like pulling a plug out of an appliance, you need the permanent live from the fused spur run to the wiring centre, then the switched live is picked up from the orange wire on the mid position valve inside the wiring centre, leave the fused spur switched on but turn the HW AND CH both off at the nest, then test the wires in the wiring centre with a multi-meter and see which ones are live and post up which numbers are
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OK, but aren't any of the junction boxes or terminal strips local to the boiler?
There will be - but I’m hoping to somehow have only one central heating isolation switch.
If I’m not mistaken it involves having an extra wire in the trunking, behind the plaster, from the heat link to the Honeywell wiring centre in the loft which can then be connected to the live coming from the fused spur.
If I’m not mistaken it involves having an extra wire in the trunking, behind the plaster, from the heat link to the Honeywell wiring centre in the loft which can then be connected to the live coming from the fused spur.
The fused spur isolates the whole system.
this makes less sense with every post, how is the nest heatlink physically wired to the wiring centre ?
Ianmcd has kindly explained a way to resolve the lack of a permanent live to my boiler and I'll let you know when it's complete.
At my son's house the permanent live is on the wrong side of the fused spur and needs changing for a properly insulated cable and moving to the output side of the switch where it will be included in the isolation procedure. Almost certainly the reason for the the fused spur having 7 wires plus earths is because it's on a ring main.(ianmcd)
We may not have heard the last of this as it still needs a Nest fitting - at which time I'll be able to renew the fused spur and have all the wires coming from the Honeywell board including the permanent live ... I'll probably have a question or two to ask
Thank you for all your help
Ray
At my son's house the permanent live is on the wrong side of the fused spur and needs changing for a properly insulated cable and moving to the output side of the switch where it will be included in the isolation procedure. Almost certainly the reason for the the fused spur having 7 wires plus earths is because it's on a ring main.(ianmcd)
We may not have heard the last of this as it still needs a Nest fitting - at which time I'll be able to renew the fused spur and have all the wires coming from the Honeywell board including the permanent live ... I'll probably have a question or two to ask
Thank you for all your help
Ray
To complete ...
This topic has been a bit confusing as I couldn't avoid referring to two different houses.
Our house had a Ideal Logik 18KW boiler fitted three years ago without a permanent live to power the cooling fan after timed shutdown.
This only became apparent when we had the same boiler fitted at a different house a few weeks ago and observed the overrun procedure for the first time.
The forth wire has now been fitted by the people who originally installed the boiler.
They chose to add a second fused spur to provide the permanent live and marked it as also needing isolating elsewhere.
This topic has been a bit confusing as I couldn't avoid referring to two different houses.
Our house had a Ideal Logik 18KW boiler fitted three years ago without a permanent live to power the cooling fan after timed shutdown.
This only became apparent when we had the same boiler fitted at a different house a few weeks ago and observed the overrun procedure for the first time.
The forth wire has now been fitted by the people who originally installed the boiler.
They chose to add a second fused spur to provide the permanent live and marked it as also needing isolating elsewhere.
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