Ecobee & Air Exchanger Questions

[cjcarlson]

Hi,

I have an Ecobee 4 unit that I would like to get connected to my Air Exchanger.

The Boiler works great.  The Air Exchanger is on it's own connection/circuit.  There are no interconnects.

The original wires going to the wall control were Y R G B.

I tried hooking up most connections to ACC-/ACC+ on the Ecobee and the unit is just not seeing anything to configure. 

When I go to configure additional equipment and get to the wiring, ACC+/ACC- aren't listed, and when I click next, the only option for Accessories is a dehumidifier.  It does not give additional options for a Ventilator / Air Exchanger.

Checking the voltages across all line combinations I get the following:

R->B = .365V
R->G = Floats
R->Y = -.340

B->G = -5V
B->Y = -13.45V

Y->G = 8.37V

My understanding is the ACC connections are a dry relay and just looking to connect a 24V source.  However, none of the lines offer 24V (The closest is 13.5V with B&Y).  My guess is this is why the EcoBee is not seeing the Air Exchanger when trying to add the equipment.

The Air Exchanger is a Carrier Performance Series HRV - Model:  HRVXXSVU1157

Any thoughts on how or if I can get this working?  It doesn't seem complicated since it's not interconnected anywhere.  I would have thought using 5V logic on the G&B lines would be enough to power it up.

Photos can be seen here of the EcoBee and the old wall controller for the HRV:
https://www.dropbox.com/sh/82cbbphbo6x7xdb/AADOQmFLOW5MM-MwPWVCtoCEa?dl=0

Thanks!
-Chris

[Admin]

If you twist B and G together the HRV should run when you plug it in, after it completes its power up test.  Connect those wires to the Ecobee ACC terminals.  Then the Ecobee should detect the connection.  Now you can set the Ecobee to run a certain number of minutes per hour.

[cjcarlson]

Thanks for the reply.

I got this resolved but wanted to come full circle in case someone else is having the problem.

1)  The voltage on the wires is irrelevant with regard to the ecobee picking up the HRV.
2)  The logic Hi/Low of 5V is correct for turning on/off the HRV - so the Green/Blue wires are the correct ones to be using.

The reason it's not an option is the ecobee wrongfully assumes you only have Ventilators with "Fan Based" heating.  Since we have a boiler and there is no fan, ecobee does not give you this option.

To fix the problem, simply override the "G" (aka Fan) wire in your ecobee equipment setup.  Tell it there is a 'G' wire even though there isn't one.

Once ecobee thinks you have a fan, it will now allow you to choose a ventilator (HRV/ERV) as an accessory.

Probably a bug to be fixed in a firmware release.  But for now, everything is working great.

Thanks again.

Ref: https://www.reddit.com/r/ecobee/comments/ejzzs4/missing_accessory_options/

[Admin]

Thank you for the update!