Nest Learning Thermostat and Whole House Dehumidifier

[fniada]

This is quite interesting...

I have a SantaFe whole house stand alone dehumidifier wired to the Nest Learning Thermostat. Under Pro setup / test I can have it running (together with the AC). This is tied to a Trane Heat Pump with electric heat, which is working without any issue.

In the Nest app, I have setup Cool to Dry off (no need to have the heat pump dehumidifying) and the humidity level at the minimum in the dehumidifier setting.

So far, Nest has not turned on the whole house dehumidifier any single time, even if it is 65% or 70% RH inside my house (and nest reading that humidity). If I change the temperature setpoint, the heat pump kicks-in but the dehumidifier stays off.

If I manually go to the Pro settings and turn on the dehumidifier (under test mode) it starts right away, and drops the humidity quite fast (it is like 2 to 3% in 10 minutes or so) - while trying to have my heat pump doing that work it could take an hour easily.

Is there a way to know why Nest is not starting the dehumidifier? or how to manually start the dehumidifier (ideally without adding a humidistat) ?

Thank you guys!

[Patrick_Caezza]

@fniada 

Let's start from the beginning.

How was the original thermostat wired? Can you post a picture of it?

How did you wire the Nest? Can you post a picture of the base plate?

What is the make and model of the dehumidifier?

What is the thermostat showing as its current humidity level? You can check on the Menu screen of the thermostat.

[fniada]

@Patrick_Caezza thanks!!

For some reason this thing is not allowing me to post pics...

Nest wiring:

Y1, G, O/B, Rc, W2/Aux, C, * (set up as dehumidifier).

Dehumidifier a Santa Fe Ultra 70 (powered humidistat or contact to start)

Nest dehumidifier humidity level set at 1 drop (all the way to the left). Inside the house in the evenings I can have about 65% rh but still it does not get the dehumidifier to kick in.

About the wiring, what surprises me is that if I select test under the equipment menu dehumidifier to test. It starts and also the hvac unit in cooling mode - which is what I would expect. But when normally running, the dehimidifier never starts. 

Seems like nest never makes the call for dehumidifier