s plan - heating only

[Simonharris]

Hi All,

I've just purchased the starter pack (5 HR92's, 1 BDR91 and the base unit.)

My current system is an S-plan design with a danfoss programmer and a honeywell wireless thermostat, I wasn't going to bother using evohome to control the hot water (at least for now anyway) so I am trying to work out where the BDR91 needs to go.

I think it needs to go where the current wireless thermostat goes and I need to change the danfoss programming so that it is "on" all the time that I want evohome to control the heating until such point that I add the boiler control.

can anyone confirm?

many thanks

Simon

[Richard]

The BDR91 'normally' wires into the wiring centre on a system or heat only boiler.

[Simonharris]

I have a wiring center, at the moment the danfoss controls the rads and hot water timing, the wireless thermostat controls the temp of the rads by calling for heat. With the Evohome that now makes the wireless thermostat redundant but I still need to control the hot water (not a combo boiler btw)

So my thought process is that I can leave the danfoss where it is for now, take out the wireless thermostat and “replace” it with the brd91 by doing a direct swap of the wiring at the wireless stat end. This would require the danfoss to be set to have the boiler on so when the Evohome calls for heat the boiler will fire.

Are you saying that if I wire the brd91 directly to control the boiler I can bypass the danfoss for heat control entirely but leave it in place to control the hot water?

[Richard]

I have a wiring center, at the moment the danfoss controls the rads and hot water timing, the wireless thermostat controls the temp of the rads by calling for heat. With the Evohome that now makes the wireless thermostat redundant but I still need to control the hot water (not a combo boiler btw)

So my thought process is that I can leave the danfoss where it is for now, take out the wireless thermostat and “replace” it with the brd91 by doing a direct swap of the wiring at the wireless stat end. This would require the danfoss to be set to have the boiler on so when the Evohome calls for heat the boiler will fire.

Are you saying that if I wire the brd91 directly to control the boiler I can bypass the danfoss for heat control entirely but leave it in place to control the hot water?

Where the programmer/room stat would normally wire into the wiring centre is where a heat only evohome would wire instead. Have a look at page 46 of the evohome Installation Guide.

[Simonharris]

I think have some form of wiring dyslexia because I can’t work it out...

I’ve got some pictures that i’ll Upload tomorrow

[Richard]

I think have some form of wiring dyslexia because I can’t work it out...

I’ve got some pictures that i’ll Upload tomorrow

Unfortunately for legal reasons I cannot help with wiring apart from point you to the relevant diagrams. If you are in any doubt, please contact a competent installer for assistance.

[Simonharris]

just for completeness I sorted this out in the end (it worked well enough with the original programmer in place but I have subsequently removed it.)

I did find that this video https://www.youtube.com/watch?v=V9rN5D-wQIc perfectly explained how everything works on an s plan system and what the wiring actually does. Made it perfectly clear in my head and I was then able to confidently make the required changes.

if anyone is having any trouble it is well worth a watch - he has videos on Y plan systems as well.

Simon