Removing Nest, Reinstalling Danfoss TP4000 - Help with wiring please (pictures included)

[jaylaw]

Hi, I'm new here.

I am moving out of my current property in two weeks.

It has a zoned heating system (no hot water control, it is on a combi boiler):

• Zone 1 - Nest Thermostat + Heatlink
• Zone 2 - Danfoss TP4000

I want to remove the Nest in Zone 1 and replace with the original Danfoss TP4000 unit.

I am happy removing the Heatlink, as this was just an addition, so I assume it is just a case of removing the wires that go into the Danfoss receiver unit and the heatlink itself? - Unless someone wishes to correct me?

Replacing the thermostat looks pretty simple, but I just wanted verification from someone on here that what I am doing is correct. I think it needs to be the same as Zone 2.

Current wiring in Zone 2 (Existing Danfoss Unit - not removing):

Current wiring in Zone 1 (Nest - wish to replace with original Danfoss Unit):

Am I right to assume that I need to move:

1. T1 (Nest) (Brown Wire) to COM 2 on Danfoss &;
2. T2 (Nest) (Black Wire) to N/O 3 on Danfoss (just as it is in Zone 2)?

Thanks All
J

 

[stem]

Don't do that if it is still connected to the Heat link T1 & T2.

The heat link T1 & T2 provides 12v DC only to power the Nest Thermostat. The wires have nothing to do with control of the heating. If you put them into the Danfoss thermostat when the thermostat switches 'on' you will create a short circuit and may damage the Nest Heat link.

You can use the cable though if you disconnect it from T1 & T2 at the Heat link end and connect it back into 'series' with the heating control wiring, but you need to understand the heating wiring circuit to understand what you are doing. You can't just remove the Heat link, otherwise the heating will be left 'open circuit' and not work. Some rewiring will be required.

 

[jaylaw]

Hi Stem

Glad I asked, thank you. I’ll get a sparkie in to uninstall it safely.

Thanks
J