Replace BG Up2 + Wr1 with Nest 3rd Gen

[ptburkis]

Hi All,

Wondering if someone can help, I've got a bit of an odd setup in my house. I replaced the Up2 unit in November last year and wired in what I thought was correct. However, this year as I've started to use the heating I've realised that there was a seperate WR1 receiver in the airing cupboard which seems to control the circulation pump for the central heating.

I can control the hot water ok from the nest - the boiler fires and the tank heats - TICK
I don't seem to be able to control the rads - the boiler fires, but nothing circulates. CROSS

If I go into the airing cupboard, the old WR1 receiver is there with a red light on it (obviously because it can't talk to the old Up2) - so I hit the override button and the the circulation pump springs into life and the central heating works.

So - it would appear that the old Up2 was communicating with the boiler directly over the wired interface to tell it to fire, but communicating with the WR1 wirelessly to turn the circulation pump on. So that now leaves me with a bit of a conundrum as I'm not sure how to get the Nest to turn on the circulation pump...

Do I need a second thermostat? Is there a wiriing change? Is there a second heatlink I can buy that will connect to the main thermostat?

I'm a little confused....

Incidentally - the boiler is a British Gas/Gloworm 330 - with a standard hot water tank upstairs in the airing cupboard.

 

[CBW]

Sounds like you need to alter some wiring, com/live and switched live. This can either be traced or done at the WR1. Might be best removing the live and neutral too.

 

[stem]

It sounds like it could be a very old system. 40 or 50 years ago when the design of systems dated back to when solid fuel was predominant, and systems began to be converted to gas & oil, the hot water control would simply start the boiler and the heated water would circulate around the hot water cylinder via natural gravity circulation. Then, when the heating was required the heating controls would start the pump which would now circulate water around the radiators. If that is the case, to get it working properly, some plumbing modifications will be required to convert it to a fully pumped system.

The bit that puzzles me though is that you say you installed the Nest November 2021. Did the heating not work last winter?

At the moment there is a quite a lot of guesswork going on, if you could provide some details of the system you are trying to control it would help. If you are not sure what you have check out the different systems on line (eg S-Plan, Y-Plan, C-Plan, Gravity hot water with pumped heating)

 

[Giblets46]

Literally have the same set up this end, the junction box they are box connected to seems a bit of a dogs breakfast!

 

[ericmark]

C Plan came in three diffrent versions. At first no indecent control of DHW temperature, then a tank thermostat was added for summer use, it removed the need for a summer timer, and then a motorised valve added so could control DHW temperature in winter.

Mine is the most basic version, and to get it to work with Nest DHW uses com to feed boiler and N/O feed in and N/C feed from CH relay, so the reverse to normal.

It's a hard fix where with Hive it was a soft fix.