Wiring support from Danfoss RMT230 to Honeywell T4

bikeman17

My Danfoss RMT230 stopped working.
Here is the wiring on the Danfoss.
https://imgur.com/ofNnEID

I have now bought a Honeywell T4.
Could someone guide me on how to get this connected to the T4?
T4 guide: https://www.plumbworld.co.uk/docume...thermostat-quick-start-installation-guide.pdf

I currently have a combi boiler which is connected to a programmer Danfoss TS715Si.

Thanks

Le_Kirk

You appear to have bought a programmable thermostat whereas you only needed a thermostat and you already have a programmer (the Danfoss TS715Si)

Jeepers_Creepers

I suspect bikeman knows that all he has to do is leave the TS71 'ON' 24 hours.

Prog Stats are great, and that looks like a nice model.

Bikeman, your Danfoss currently has:
LIVE to 1
NEUTRAL to 4
Switched Live (the one that controls the boiler) to 2

Your T4 is battery operated so doesn't require the neutral. This should be safely terminated behind the 'stat*

You connect:
LIVE to A
Switched Live to B

*Neutral wire: get a single terminal connector and shove the bare wire in there so it's safe. Or, snip off the bare wire end, fold around 10mm or so over itself and tape it securely. DON'T cut the actual cable any shorter than you need to - you might want it again later on.

Jeepers_Creepers

ARE THERE three wires AND an earth going to your current stat? 

Le_Kirk

Jeepers_Creepers said:

I suspect bikeman knows that all he has to do is leave the TS71 'ON' 24 hours.

Yep, agreed but it seems like overkill to have two programmable controllers (two things to go wrong) when all he needed was a new thermostat and the latest digital ones with a battery will work to +/- 0.5 Deg C.  Also agree with your wiring answer.

Jeepers_Creepers

His purchase of a T4 seems a fait accompli, so - as a DIYer, which I presume he is - all he'd need to do is leave his TS715 'on' permanently. If he is more capable, he could remove and by-pass this completely and that is the ideal scenario tho' not needed.

I certainly wouldn't discourage him from changing to a Prog Stat, tho' - once used to their convenience, there's no going back :-).

bikeman17

Thanks all for your input. Yes I am aware I have to leave the current programmer to always ON.  
Appreciate the wiring advise. I'll keep you posted on how I get on but probably won't be before the weekend. 

Jeepers_Creepers

Cool.

Do you understand what you are doing, or just following instructions blindly?! I mean, do you know what the Live and Switched Live wires are, and what they do? And you won't get them mixed up with the neutral, will you, 'cos that'll be 'bang' territory - and an ex-T4. :-)

bikeman17

Jeepers_Creepers said:

ARE THERE three wires AND an earth going to your current stat? 

Yes three wires and the Earth (Yellow) was not connected.

Jeepers_Creepers

Cool. Then wire as post 3. Essentially, Terms 1 and 2 go to A and B respectively. 

Safely isolate - but don't snip back - the unwanted Neutral that used to go to 4.

Does you stat have a metal backbox behind it? If so, hopefully the earth wire is going to the terminal on there? If there isn't a backbox and nowhere to 'park' the earth wire on the new stat, then safely isolate it like the neutral (again, don't trim down).

bikeman17

Regarding the metal backbox, not sure about the current one as it's still on the wall. The new stat has arrived today and cannot see a metal box.
That's fine I'll be able to safely isolate it.