Anyone know how to connect a HRV to the Nest learning thermostat gen 4?

[Dilon_V]

I have a heat pump, electric furnace, and a HRV ventilation system as part of my central air system. Does anyone know how I can wire the HRV system to work with the Nest Learning thermostat gen 4? I currently have 2 leads going to an air exchanger control box in my living room (Fantech EcoTouch). 

Do the two leads connect to the AQ+ and AQ-?

TIA

[aperezdeleon]

Hello Dilon_V,

Thanks for reaching out to our community.

Optimizing your ventilation system is a key feature of your Nest thermostat 4th generation. Let's explore your options for setting it up.

Your Nest Thermostat 4th generation should be compatible with your HRV ventilation system. As you mentioned, you can use a main and a secondary wire in the AQ+ and AQ- terminals respectively to connect it to your thermostat. However, it's important to understand what are the primary functions of the wires in your control box so ventilation can be activated correctly.

I suggest contacting one of our recommended technicians to have your ventilation system checked and installed. This will help you get the most out of your new Nest thermostat.

Please let me know how it goes.

Regards,
Angel.

[Fitjarald]

Hi Dilon did you get this resolved? I have the same HVAC (fantech ecotouch) with 4 wires, and am trying to troubleshoot the connection.

[Dilon_V]

Hi Fitjarald,

I was able to get it work. Although my HRV system only has two leads going up to my fantech ecotouch controller. The two leads were connected to "W" and "W" on the HRV unit itself. I changed that to "D" "D" on the HRV unit because for some reason leaving them on "W" "W" was causing the HRV unit to cycle ON/OFF instead of staying on. Once I changed the two wires to "D" "D", the system seems to function normally. On the Nest, I connected the two leads to AQ+ and AQ- and I configured these two inputs as "Ventilator" during the Nest installation steps on the app.

One thing to note!! Make sure to take off the power plug from the wall to the HRV unit (or turn off breaker) before trying these changes. I accidently blew my DirectAir HRV unit's controller board by trying different things because the power was still connected to the wall. 

Good luck!