I was wondering if anyone can help me get my head around this, picked up a Nest in a Black Friday deal and trying to work out how to install it.

I have an Ideal Heat 15 boiler, Danfoss TP9000MA-Si thermostat next to the boiler, Danfoss TS2 remote sensor in the hall and a Danfoss (either TP4000/TP5000Si/TP5000/TP5001+RF - unsure which) thermostat in the lounge.

From what I can tell the lounge thermostat has an inbuilt sensor, when I take the cover off there are 2 wires in terminals labelled COM and N/O. The wiring diagram is here http://assistyou.danfoss.co.uk/PCMPDF/TP5000%20Si.pdf

The TS2 in the hall has 2 cables too and the TS9000 has one cable in N, 3 in L, one in 3, 4, 5, 6. The wiring diagram is here: http://heating.danfoss.com/PCMPDF/TP9000.pdf

I found the following site which has some useful info: http://www.aimlesswandering.uk/web/2...-nest-3rd-gen/

I've read up and Nest say for a zoned system you need multiple Nests (or can have one nest for one zone and the existing system for the other zone) but I can't work out if I would need two heat links if I have 2 Nests? if I do then where/how are they wired up? If I install a Nest in place of the lounge thermostat would I have to keep the TS9000 in-place and link the heat link directly to the boiler or to terminals on the TS9000?

I've watched guides on YouTube but thought people here would have done it themselves already and have some hints