Changing a Honeywell Programmer

[Mucka]

Seem to be having problems with my heating system where the Honeywell programmer keeps turning itself off all the time. This means i have to reset it to get the boiler up and running again on a regular basis. Im looking at changing the programmer to see if this is the cause but cant seem to find a replacement one the same. Its a Honeywell ST712. Does anyone know where i can purchase one online or if another one similar can be used to fit the back plate so i dont have to rewire the thing. I found one on controlscenter.co.uk but this was for the whole y plan system which was near £200.00.

[NeilUK]

Go for a Honeywell ST6400, it should be a direct replacement but is a 7 day timeclock rather than a 24 hour i.e. you can have upto 3 on/off times per day with different times for each day of the week.

If you go to the RS website and search for ST6400 you will find a link to a datasheet that includes wiring information. Even if the backplate is not comaptible (although I'm pretty certain it is) it would be easy to change over as long as you label the wiring first.

[Mucka]

Many thanks for the reply. I will give it a go.. cheers.

Also do you think this tripping out/turning off of the programmer sounds like a fault of the programmer or something else.

[NeilUK]

I've never had a central heating programmer lock up or require resetting so it does sound like a programmer fault to me.

[sunbeam]

What make of boiler do you have mucka?

And what kind of heating system?

[Mucka]

I believe it is a Potterton Suprima about 10 years old. Had someone to look at it when we moved in about 6 months ago as the boiler kept locking out. The problem then was that you had to keep one radiator on all the time to keep a flow of water going in the system when the boiler is on so it didnt over heat. This seemed to fix the problem until about 2 months later when the programmer kept tripping out. The boiler fires up fine no problem when the programmer is reset so it makes me think that it might not be the boiler. But could be wrong. I know that the boards on these boilers are very dodgy so if the new programmer doenst work this weekend then i might look at changing it. Do you know is it easy to change and where the best place to purchase one is.. Any other ideas?