Evohome wiring setup sanity check

[forty_beans]

Hi all,

Firstly, thanks very much for hosting such a helpful site as a free resource, there’s so much great info here and I appreciate the effort that goes into running the site.

Full disclosure – I’m not currently an Evohome shop customer. I recently bought the Honeywell Connected Thermostat package from Argos with a 20% off code. However, I plan to add about a dozen TRV’s to the system as I scale it out.

I’ve spent some time today documenting the boiler and controls wiring in my existing setup. This proved a bit challenging as I’m not a spark or heating engineer, plus the house has two colours of wiring in it, so it took a bit of time. However, I’m confident this is how its presented now: (NB. the neutral wiring on the frost stat isn't complete but i dont believe its wholly relevant in this case as its fully seperate)

https://www.lucidchart.com/documents/vi ... d2269d26/0

The system is as follows:

Garage
Worcester Bosch Greenstar classic 34Cdi (installed feb ’16)
Sauermann Si82 condensate pump (installed feb 16)
Honeywell Frost stat (installed unknown)
Drayton PTS1 on heating return (installed unknown)

Kitchen (approx. 12m from boiler through block walls)
Invensys (British Gas) UT2 programmer

Hall (leads to kitchen)
Honeywell T40 thermostat

So far so good (I think) so I started looking at how the BDR91 would fit into the existing setup. Looking at the diagram, with the assistance of this site

http://www.ultimatehandyman.co.uk/forum ... 73938.html

I believe you just need to wire Lr and Ls to B and A respectively, as the live to the boiler is already established via the existing wiring. Looking at the existing wiring for the controls in place I think I could put the BDR91 in the kitchen, utilising the existing 4core and earth wiring there for the programmer. This would cover the existing hole, reduce wireless interference and simplify my task.

I would achieve this using the wire denoted (1) in the programmer, connect to A in BDR 91. This already connects to Ls. Output (3) from the prog would be jointed to the grey wire going to LR in the “wiring centre”, previously output 3 from the thermo. I write in quotes because its basically a single gang box with a blanking plate, so not a lot of room, but it would be possible. Here’s the new wiring diagram based on this:

https://www.lucidchart.com/documents/vi ... f1820718/0

So, it looks easy enough but that’s taking on some big assumptions

1. I’ve not fundamentally misunderstood something
2. The web resource for the suggested diagram I’ve used is not wrong
3. The existing wiring beyond the prog/thermo can remain as is and unchanged
4. The PTS and frost stat are completely separate so play not part in this.
5. Putting the BDR91 in the kitchen isn’t a major issue

I believe looking at the documentation there’s a recommended minimum gap for the relay, but I can’t see anything about a maximum. There’s also not much on installing it in a garage, but i haven't searched exhaustively. There is plenty on wireless interference so it stands to reason that closer is better (to a point) The suggested location of the BDR would be approx. 3m from the evohome controller, so I see no issues with this.

I’d welcome and comments or discussion on the plans and potential pitfalls of the setup. Likewise, any warnings will be heeded – If I’ve made a massive boo boo in my reading of this I will step back and let a pro do it, but I have enjoyed the learning to date and would like to see it through if possible. But, safety first.

Thanks again

David

[Richard]

Hi David,

Although we have an open forum for general discussion, any in-depth technical discussion with regards to setup and wiring of the evohome system is exclusively for 'The EVOHOME Shop' customers who have purchased their full evohome system from us.

Unfortunately (and you may not appreciate the fact), without purchasing the full evohome system from us it does not make it viable for us to spend our time with support or give our knowledge for free... After all we are an independent online retailer of the evohome product and not Honeywell, so any support we give is deducted from the profit we make on the evohome system we have sold.

The information we have already posted publicly in the past should be sufficient to aid basic understanding or alternatively there is some limited information available on Honeywell's website - https://getconnected.honeywell.com/en/support

Good luck with your installation.

Kind regards,

Richard

[forty_beans]

Hi Richard,

Thanks for your quick reply. I understand and fully appreciate your position and respect that in-depth support from your company is reserved for customers only - i read the FAQ's before posting.

i noted a few threads with posts by other users of the forum, so if forthcoming I'd welcome their views. However, I appreciate this is at your discretion as forum owner so if you'd rather i removed the post then please let me know.

Thanks again and best wishes,

David

[Paul]

Did you get your system up and running?

Paul