Wiring up a honeywell pipestat to an existing frost stat


7 Oct 2005
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United Kingdom
I have a setup with a boiler in the garage and a honeywell T4360 frost stat just above it. I need to add a pipestat to avoid the heating being on all night in the winter so i bought a matching honeywell L641B pipestat.

my frost stat has 2 red wires attached (as per picture). My pipestat instructions say to attach wires to 'C' and '1'

An FAQ from honeywell on the combination of my frost stat attached to my pipestat has a fairly simple diagram of a 'Live' cable coming into terminal '1' on froststat and then going from '3' on on froststat to terminal '1' on pipestat and then from 'C' on pipestat to terminal box.

I'm assuming that for me its a straightforward case of disconnecting my current wire attached to terminal '3' on froststat. I then put in in a new cable from '3' to pipestat and then return from pipestat joins up with my disconnected froststat cable.

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The Permanient live goes into 1 on the F/thermo & out on 3.
From 3 on the F/thermo it goes into 1 on the Pipe/thermo & out to the controlled item on C from the Pipe/thermo.

So ensure you have a permanient 240vac supply on 1(F/thermo) & connect as above(or as you stated).
Tricky Dickie............ ;)
Oh, just one other thing; I take it you know what you are doing with electrics?? And don't blow yourself ta f.ck!!! Use a good multimeter & make sure the supply is isolated, check & double check!!
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Thanks for the input guys and I am fine with handling electrics. It seems a straightforward job and I'll ensure there is no live leccy when i do it...

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