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Replacing Manual CH Thermostat with Digital one

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Registered: 16-10-2014

Replacing Manual CH Thermostat with Digital one

Given a product like this:
http://www.meteorelectrical.com/timeguard-digital-room-thermostat-with-night-set-back.html
how do I know if this compatible with my boiler, or is there a standard that applies here?
Is it a one-for-one replacement or do wires need to be ran back to the boiler?
4 REPLIES
sjptd
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Registered: 01-09-2014

Re: Replacing Manual CH Thermostat with Digital one

I fitted something like that a few years ago, just straight replacement for the old thermostat.
Typically they just have two wires (warning, mains voltage); effectively input and switched output.
The old one had an earth as well as it had metal casing.  No earth connection for the new one.
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Re: Replacing Manual CH Thermostat with Digital one

Thanks for that sjptd. I'll ask the gas engineer when he calls if he'll fit it for me, but if it's mains voltage then it may need a spark.
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Re: Replacing Manual CH Thermostat with Digital one

I fitted one of these a couple of years ago.
It has a 3 wire block connector but only 2 were needed as per the original wiring to the old mechanical room stat.
It's a bit more pricey than the one you linked to but it's fully programmable and varies the temperature at points throughout the day.
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Re: Replacing Manual CH Thermostat with Digital one

Well this is a timely thread, I'm just looking at replacing my room stat (Sunvic TLM 2253) that doesn't seem to work below 20deg with <nothing fancy> a Drayton Combi-Stat RTS8. Straight forward rotary manual stat.
It is by no means obvious how the new stat wires-up. The old stat is 3 wire blue, yellow and red plus earth. There is a schematic wiring diagram inside the stat that doesn't actually seem to agree with the connection terminals, however the yellow appears to be connected to the fixed contact on the stat itself, There is 240 volts that changes between red and yellow whether the stat is open or closed, the blue seems to be neutral.
Yellow on what seems to be terminal 1
Red seems to be on terminal 3
And the blue on terminal 4
The new stat has a terminal block labelled L 3, 2, N  with a connector block for the earth (the stat is double insulated so the earth is not needed, so its just somewhere to put the earth)
Which leaves me thinking that the new stat wires:
Blue = N
Red = L
Yellow = 2
But is this right?
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