I have a feeling it is to do with Google taking over Nest?
When I moved in I had a problem, in the Utility room there was a programmer, which said I could select DHW or CH+DHW but only two wires between it and the boiler so realised it could not do what it said, found a wire sticking out of wall in hall which connected to programmer, but no thermostat, down in the flat under the house where the boiler is, found a wireless thermostat receiver but nothing to connect to it, and a second thermostat which connected to boiler and one pump so it would heat flat, but to get main house warm needed to go down into flat and plug in second pump. Also three FCU's and a CU plus fuse box all connected to central heating, and even when pump not running radiators got warm, but not hot, and only some radiators.
So my main problem was how to control the heating when only two wires, and also since it started as red, yellow, blue but ended as brown, black, grey would be better if extra low voltage as no idea where the cable was joined.
I looked at Nest Gen 3 and two wires between wall thermostat and heat link would keep thermostat battery charged and also send data to heat link to control both CH and DHW so it seemed an easy way around the problem.
I also added a couple of motorised valves so flat and main house independent from each other, and 9 electronic TRV heads, it was claimed 4 of these worked with Nest which was another reason to get Nest as already had the TRV heads from last house.
The DHW is still a small problem, as no tank thermostat, but ½ hour every other day in Summer seems to work reasonable. And advised better for boiler which has no cool down system that thermo-syphon remains with no motorised valve for domestic hot water.
Earlier this year lost connection with Phone and PC and it seems I was forced to migrate to Google from Nest. But prior to that been working well.
It did work with GeoFencing, but to be frank, with an 18 kW boiler and a house with three floors only way to reheat fast is to select which radiators heat first, so simply times work better, 4 of the TRV head also can have GeoFencing, but again used simply timed changes. As to savings since never worked without Nest and programmable TRV heads can't say, more worried about comfort.
I prefer it cool when sleeping, so switches down over night, then in the day it increases at 0.5°C every two hours which ensures there is hot water circulating for the TRV heads to control. Jumping direct to evening temperature it tended to over shoot.
But as said worked OK last year, but this year seems to be auto changing to Eco Mode read that as cold room mode.
) thingies that are being purchased!
