In an earlier contribution to this discussion,
Kostas Kavoussanakis wrote:
Hi,
I would like to replace my old (80s) Honeywell room thermostat with
the 907. It's a very common model.
On the old thermostat there are 5 terminals (top to bottom): 5 2 3 4
1. Of these, 2 (Neutral), 3 (Switch Live) and 1 (Live) are connected.
I understand that the 907 only accepts two wires.
It actually *accepts* 3 - but you only need and *must* only use 2.
According to the diagram in the document you sited, the three a
A: Common - (Use the Live from the old stat)
B: Call for heat - (Use the Switched Live from the old stat)
C: Heating Satisfied - Do not - repeat DO NOT - connect anything to that.
Your old neutral wire is not required. Disconnect it and tape it off safely.
DO NOT connect it to anything.
Is my installation compatible with the 907? The installation manual
suggests current needs to by 8A; how does one check that?
You have to make sure that you're not asking it to switch more than 8 amps.
If you're simply switching the boiler and pump and/or a motorised valve, all
of those together are likely to take less than 5 amps, probably no more than
3 - but check the spec of all the relevant equipment.
http://europe.hbc.honeywell.com/prod...7uk07r0906.pdf
Am I right that this a DIY job? I know I need to switch the boiler off
at the mains and drop the fuse while the wife and kids are out
shopping :-)
Your last question worries me! It's a simple job - well within the scope of
a *competent* DIY-er - but the fact that you had to ask, and couldn't work
it out from the Honeywell literature - not to mention being uncertain as how
to isolate it when working on it - makes me wonder whether maybe you should
be getting some professional help.
Also, it's a moot point whether it's notifiable under the dreaded Part P -
since central heating controls seem to come within its scope. I'm not sure
how convincingly you could argue that it's a 'like for like' replacement.
--
Cheers,
Roger
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