Wireless Theromstat Installation Help

[Rob1982]

Hi Guys,

I have a brand new Vaillant ecotec plus combi boilder installed and need to wire up my new wireless CM900 thermostat and BDR91 relay box.

At the moment i cant see how the to 2 wiring diags marry up so id like some help with what needs to connect to what.

combi boiler diag:

Untitled

• Rob1982
• 25 Oct 2009
• 3

relay box diag:

Untitled

• Rob1982
• 25 Oct 2009
• 2

Cheers.

 

[bengasman]

Why didn't your installer connect the roomstat? Technically speaking, he left an incorrect installed boiler as he could not have signed off the benchmark truthfully as correct, and you risk forfeiting your warrantee by doing diy on it.

 

[Rob1982]

I was told at the time that this is a job for the spark which in this case is me. If this should have been done by the plumber then its to late now.

The boiler could still be operated through its controls so the fitting being complete would appear resonable to me.

Either way I'm doing it now.

 

[bengasman]

So be it.
Switch wires from stat to 3 and 4.
L&N to feed outside boiler, but I guessed you worked that part out.

 

[picasso]

here is how to connect the bdr91

boiler....................bdr91

5...........................N

3...........................L

4..........................B

link L and A in the relay box.

 

[Rob1982]

Cheers for the replies guys.

Just to confirm, i must remove the bridge between 3 and 4 on the boiler as it says?

Also, would it be ok for the relay to get its power from the L and N terminals inside the boiler, marked as Mains Supply: 230 V/50 Hz?

I ask because its going to be difficult to get another cable from the switched spur.

or is this not a good idea?

 

[bengasman]

Remove bridge.
Connecting to he live terminals in the boiler is effectively the same as connecting to the spur, should work fine.

 

[Rob1982]

cool, thanks for the help.

 

[Rob1982]

just realised, the relay box has 2 L's. Which L needs to be connected to A?

 

[Norcon]

just realised, the relay box has 2 L's. Which L needs to be connected to A?

You shouldn't be wiring this asking such questions!
Get an electrician in.

 

[Rob1982]

if you dont know the answer, dont post.

 

[bengasman]

Are the 2 l's internally bridged?

 

[Norcon]

if you dont know the answer, dont post.

I do know the answer but feel you are out of you're depth to be attempting this.

 

[Rob1982]

Are the 2 l's internally bridged?

I only have the diags that i posted pictures of to go on and they do show a connection between the 2 in each one.

I guess iv answered my own question as either will do since they're connected in the device itself?

 

[bengasman]

Are the 2 l's internally bridged?

I only have the diags that i posted pictures of to go on and they do show a connection between the 2 in each one.

Did someone knick your tester?