Removing combi’ boiler timer…

Removing combi’ boiler timer…

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Sammo123

Original Poster:

2,141 posts

188 months

Sunday 20th October
quotequote all
We’ve got a combi’ boiler with an old mechanical Danfoss timer. The timer hasn’t worked since we’ve lived here and our ancient thermostat will only turn the heating on when it’s turned up to full.





I want to replace the thermostat with a combined ‘stat and timer and get rid of the Danfoss timer. Any clues on what I need to do with the wiring from the timer to enable the boiler to be switched on when the new ‘stat tells it to?


.:ian:.

2,336 posts

210 months

Sunday 20th October
quotequote all
The blue and yellow wires into the timer carry the switched live, but you need to work out where this comes from and goes to.
Usually it would go:

Live > programmer > thermostat > boiler

But in this case the stat and timer could be the other way around and it would still all work fine.



wildoliver

8,993 posts

223 months

Sunday 20th October
quotequote all
Ok I've had to do a bit of this recently.

Most of these boiler controls tend to follow a pattern, that one pictured definitely does. The red/black and earth wires are power, 240v from the boiler to feed the switch. The only purpose is to operate the switch, the same wires feed a modern radio controlled unit.

The wires on the left are the ones that turn the boiler on and off. Basically if connected together the boiler runs. Disconnected it doesn't. That's what the switch is doing. They are simple things.

I suspect your two "switches" are in series so both need to say go for the boiler to go.

If you do just connect those two wires so you only use the stat to run (sensible) you need to do something with the power wires. At the very least screw a terminal box or something to the wall. Don't leave live wires exposed please!

I'm not a boiler expert. Take with pinch of salt etc.

Mr Pointy

11,821 posts

166 months

Sunday 20th October
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What's the make & model of the boiler?

megaphone

10,933 posts

258 months

Monday 21st October
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Yes what boiler? You need to take a look inside the thermostat and identify what wires run to it.

Rough101

2,286 posts

82 months

Monday 21st October
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Easiest way is to look at the boilers own wiring diagram, disconnect this stuff and wire in a wireless system local to the boiler with a remote stat and online programmer.

trickywoo

12,289 posts

237 months

Monday 21st October
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Be careful would be my advice.

I had a plumber install a new boiler and he ended up with a controller he wasn’t familiar with due to supply issues.

Despite being in the phone with the tech support he managed to wire it up wrong and it shorted spectacularly, think indoor lightening strike. It’s a funny story now but not so much at the time.

He went outside for a bit to regroup and I saw him through the window holding his head in his hands. To his credit he took a deep breath and was back in 5 minutes and got it working. He did then get a controller he was familiar with.