Wiring new thermostat

[Jay919]

I've been living with an ideal w rs450 gas boiler for some time using a Honeywell st6300a programmer. However I've found I dont like the lack of control with this so I decided to purchase a Honeywell y87rf wireless thermostat so that I have better control over the temperature in the house. The problem I'm having is that there is currently a Honeywell 42005748-001 wiring centre installed and the terminals are of course labelled up differently between the 2 Honeywell products.

I believe from looking at the thermostat wiring diagram that I need to connect the neutral to boiler neutral which I believe is no 2 on the wiring centre.
Live to no 1 on centre
The second live to the terminal a on receiver backplate
Then 3 goes to b
But then where would c go?

Is anyone familiar with these able to advise?
Thanks

 

[ericmark]

It would seem you need a 5 core cable, although only 4 cores used, earth needs to be in the cable even when not connected to anything, so right bottom you have line, neutral and earth, which will power the base unit all the time, and left diagonal opposite there is a set of 4 terminals clearly marked room stat with a link these go to A/B on new unit.

It may be possible to get away with 3 core and earth but personally I would power Evohome base unit all the time, so when there is a wireless signal it is not missed.

 

[stem]

The wireless thermostat and its associated BDR91 is only capable of controlling the central heating. It doesn't have hot water control which you will still need. Therefore, the Honeywell st6300a needs to stay connected to provide the hot water control, and the BDR91 receiver connects to the wiring centre roomstat terminals. As they are presently empty apart from the link between (1) and (3) I assume that you don't presently have a room thermostat anywhere. If you do please give details. If not here's how to install the BDR:

1) Remove the link between roomstat (1) and (3) at the wiring centre
2) Connect the BDR (N) terminal to the wiring centre Roomstat (2)
3) Connect the BDR (L1) terminal to the wiring centre Roomstat (1)
4) Connect the BDR (B) to the wiring centre Roomstat (3)
5) Insert a link between BDR (L2) and (A) as shown in the diagram.

There won't be a connection to BDR (C)

The central heating should be set to be permanently 'on' 24/7 at the Honeywell st6300a so that it doesn't interfere with the new wireless thermostat

 

[Jay919]

Yea I will be keeping the st6300a and again yes there is currently no room thermostat.
What you've said makes perfect sense, ipp give Tina go tomorrow. Thanks!

 

[stem]

I've just realised that the Honeywell y87rf comes in two versions. if you have the Honeywell Mobile Access Kit (RFG100) which allows the wireless thermostat to become a wireless ‘Connected Programmable Thermostat', then proceed as my earlier post.

If you don't have this option and it is just a basic thermostat (ie not programmable to give just temperature control only and doesn't have time control built in) the wiring will be different. So post back if you need this option instead.

 

[Jay919]

I have the y87rf2024 which is compatible with the rfg100 as an added extra so I believe your instructions still stand