Honeywell EvoHome with Vaillant 938 boiler

[Quechua]

I am trying to put in a Honeywell EvoHome and use it with my Vaillant 938 boiler (I believe Vaillant 938 and 838 is technically the same boiler). So any help here should be useful to the users of 838.

Does anyone have any ideas which wires will go where for the Wireless relay (BDR91)? BDR91 is the EvoHome relay portion portion which attached to the boiler.

For BDR91, I have the Live (L) and Neutral (N) wired up to mains and A and B connecting to (Vaillant 938 Terminal) Bus – (and) + respectively.

Pictures of BDR91 and Vaillant 938 terminal is attached.

[top brake]

Do not connect to BUS

Connect to switched live or 24V input according to boiler instructions.

[Quechua]

Thx Top Brake

Any heads up on which terminal will go where will really be appreciated.

[top brake]

Thx Top Brake

Any heads up on which terminal will go where will really be appreciated.

Do you have the boiler installation manual? Will be a page in it with the information you need to identify the right terminals. If you're not au fair with this I strongly recommend getting an installer to do this for you.

[The EVOHOME Shop]

Thx Top Brake

Any heads up on which terminal will go where will really be appreciated.

BDR91 A & B to the purple RT 230v terminal and ideally the live from the RT 230v terminal to A of the BDR91

[Quechua]

I actually would l like to use the SCENARIO 2 from the attached.

Any ideas the advantage I would have if I go for SCENARIO 1?

[The EVOHOME Shop]

I actually would l like to use the SCENARIO 2 from the attached.

Any ideas the advantage I would have if I go for SCENARIO 1?

SCENARIO 1 is your only option.

[Quechua]

I have used SCENARIO 2 for for last one day and its been working fine. The temperature around the room regulates pretty well and as expected.

The advantage I see with SCENARIO 2 is that its pretty straight forward wiring.

Are there any disadvantages anyone can see here?

[The EVOHOME Shop]

I have used SCENARIO 2 for for last one day and its been working fine. The temperature around the room regulates pretty well and as expected.

The advantage I see with SCENARIO 2 is that its pretty straight forward wiring.

Are there any disadvantages anyone can see here?

Why is it any easier? Big downside is someone could mistake it for 230v and blow up the PCB! Easily done with the BDR91 and the potential for the link wire from 2nd L terminal to the A terminal.

[vishaljh]

I actually would l like to use the SCENARIO 2 from the attached.

Any ideas the advantage I would have if I go for SCENARIO 1?

Hi,

I am also in the process of installing evohome with a Vailliant Ecotech plus 938 as the OP.

Scenario 1 was recommeded but the image quality for the scenarios is extremely low and I cannot make out what to connect where. My builder is corgi certified and he is doing the install but he has never fitted a BDR91 relay and hence some guidance here would be really appreciated.

can someone please tell me where was the image sourced from or can provide a high quality image. Or a simple Wire A goes to x and wire B goes to Y on the boiler, that would be great.

[Quechua]

Hi,

I am also in the process of installing evohome with a Vailliant Ecotech plus 938 as the OP.

Scenario 1 was recommeded but the image quality for the scenarios is extremely low and I cannot make out what to connect where. My builder is corgi certified and he is doing the install but he has never fitted a BDR91 relay and hence some guidance here would be really appreciated.

can someone please tell me where was the image sourced from or can provide a high quality image. Or a simple Wire A goes to x and wire B goes to Y on the boiler, that would be great.

I have sourced the wiring diagram from Vaillant and I have been using the scenario 2 for a while now (since my first post).

One downside I saw with scenario 2 was that I was unable to turn off the hot water at will (whenever you want to). It will be automatic mode and will be using this even on summer days. On hindsight, this is not really an issue.

Works perfectly otherwise and I was very conscious to avoid the while hoopla at avoiding playing around with 230v wiring.

[vishaljh]

I have sourced the wiring diagram from Vaillant and I have been using the scenario 2 for a while now (since my first post).

One downside I saw with scenario 2 was that I was unable to turn off the hot water at will (whenever you want to). It will be automatic mode and will be using this even on summer days. On hindsight, this is not really an issue.

Works perfectly otherwise and I was very conscious to avoid the while hoopla at avoiding playing around with 230v wiring.

Thanks a lot.