Wiring HomeExpert controller to Main Combi 24 HE

[PaulKnappett]

Hi all

My first post, so please be gentle!

I have a Main Combi 24 HE boiler with integral CH timer, and want to replace the timer with a programmable thermostat. The one I prefer is the Honeywell Homexpert THR872CUK Wireless Programmable Thermostat.

Is this possible? It looks as though I remove the link between T1 and T2 on the boiler, and connect these to the external controller, but does this disable the internal timer? I need to be sure what I'm doing before I start. I'm OK with general wiring, but not sure about boiler controls!

Many thanks for any help.

 

[gas112]

yes remove that link and use those terminals but just leave integral clock on constant

 

[PaulKnappett]

Brilliant! Thank you

 

[PaulKnappett]

If anyone else is wondering about wireless programmable thermostats, I am extremely pleased with this one. It was a doddle to install, took about 20 mins. It comes with a default 7-day setup with 6 periods per day, which will get you started, and all aspects of the programming are very easy to change.

Best thing is, rather than wall-mount it, it also has a table/shelf stand, so can be taken at any time into the room where it's most needed. Communication between wireless thermostat and relay box by boiler is faultless.

Not cheap, but I think it is money well spent.

 

[stuartrambo]

hi, sorry to butt in on your thread, i am looking to do something similar to what you have done but on a main eco 30, i guess that it will be the same process as described for your boiler?. with the integrated clock in place and set to constant. out of curiosity what happens when you flick the pips over to 'off'?
sadly i think i failed with the wireless roomstat that i have purchased. user interface looks like it's going to be a nightmare. wish i'd spent the dosh now
thanks for your help

 

[PaulKnappett]

Sorry you've had a nightmare so far - doesn't help the confidence! Don't know about your boiler specifically, but am guessing it will be wired the same, being a Main. When integral clock is set to constant, you can do what you like with the pips - they will be ignored. I've set mine all to 'off' simply because it looks tidier

 

[stuartrambo]

ok, cheers for the post. could i ask another question. now that you have the external roomstat, if that is NOT demanding CH are you able to manipulate the integral clock so to force CH on? the reason i ask is that, i would like to be able to occasionally turn the heating on, but the interface on the wireless roomstat isn't that friendly, so i thought that using the integral clock be a quicker means. just not sure if that logic will work.

 

[PaulKnappett]

No, you can't. By fitting an external stat in place of the original short link on the boiler connection block, you have introduced a second switch, and both need to be 'on' to get CH. This is why the integral clock should be left on constant all the time, because if it switches off you'll get no heating at all!

The way I get round the quick boost issue is simply to turn up the temperature on the wireless thermostat for as long as I need - on the Honeywell this is just by pressing a button to increase room temp by 0.5 degree at a time. Then I either turn it down again, or wait till it gets to the next programmed period when it will revert to programmed settings.

I don't set my thermostat to 'off' during cold weather; I just program a lower temperature at night so CH doesn't come on until whatever time I want in the morning. Beauty of a 7-day model is that you can set weekends different to weekdays. Mine also has a couple of override buttons for if you are going away for a period or staying at home on a weekday; you don't need to change the normal program.

 

[stuartrambo]

cheers for your time. my wireless control panel should do that, but for some reason, when ever you ramp up the set point to bring the temp up, for instance you have guest and i want it warmer. it seems to change it permanently. really annoying. so i have to go back in to programmer mode to knock it back down to the normal set point that i want. really wish i had done my research on the timer/ stat now. especially as i spent a reasonable amount of time researching the boiler. haha.