controlling separate A/C and radiant systems with single Nest

jfmhh

In my living room area I have a Nest thermostat controlling my (new, rarely used) AC system. I have a Tekmar 510 controlling my completely separate radiant heat.

They both work well but I would ideally like to consolidate into the Nest (so that I get remote control).

The A/C is connected to the Nest with wires Y1, Y2, G, RC and C.

The Tekmar has 4 wires - R, C and 2 wires (white and gray) that connect to ports labelled 6 and 7 that, from looking at the control board on my radiant distribution board, is simply a switch that connects to the relay.

Various internet posts indicate either it cannot be done …or I need to connect the radiant to RH and W1. But which wires to connect? The white / gray pair? Or can it not be done?

Thanks in advance,

John

HVACNUT

You are correct, 6 and 7 is just a switch. So then Rh and W will be the new switch on the Nest. It shouldn't matter which wire goes where, the CAC power is doing the switching. But if it doesn't work one way, switch them. The Nest will probably need to be set up again.

No slab sensor?

That being said, radiant should be set it and forget it. No set backs, or, "I'm hot. I'm cold." And even if there's no floor sensor, the Tekmar is a far superior thermostat for radiant than a Nest.