Hi and thanks for taking the time to read this. I am trying to get a HRV unit connected and interlocked with my furnace. I do have a basic understanding of HVAC and HRV systems but am in no way an expert... so please be patient with me.
The HRV is a Nu-Air NU145 model which i believe is likely an older or discontinued unit as the unit listed under that model number on Nu-Air's website does not look like what I have here and the connections are very different.
The HRV has 3 blocks of connections on its right hand side (when looking at the device) where the power button is and they are marked as block 1: (Remote) HUM, INT I, CONT II, / 2: (timer) LED, Switch / 3: (furnace interlock) In (R), out (r).
I like to be able to interlock this to the furnace so that it can run when the furnace fan is running and be able to switch it off using the power button on its side when its not needed or in the summer as we have an AC installed.
My furnace has a iComfort E30 thermostat and a smart hub
questions:
Would I be able to connect this the way I mentioned with what I have or do i need more parts etc: relays/controllers ?
Does the HRV have a built in relay? Can I just use the Furnace Interlock ports to connect to my furnace? How do I connect this to my furnace or thermostat?
Your help is very much appreciated.
Thanks
Connect a wire from the furnace R terminal to the HRV IN (R) terminal.
Connect a wire from the furnace G terminal to the HRV OUT (G) terminal.
The interlock would start the furnace fan anytime the HRV was turned on. The relay would already be installed inside the HRV.
Just make sure the AC does not run when the HRV is turned on. The newer models include a 3 wire interlock method but your HRV only appears to have the 2 wire method. Sometimes power will back-feed from G down Y and start the AC with the 2 wire interlock method.
Thanks for the super fast reply...
"The interlock would start the furnace fan anytime the HRV was turned on. The relay would already be installed inside the HRV."
In this case, what would trigger the HRV to start? Would I need to install a timer / thermostat?
"Just make sure the AC does not run when the HRV is turned on. The newer models include a 3 wire interlock method but your HRV only appears to have the 2 wire method. Sometimes power will back-feed from G down Y and start the AC with the 2 wire interlock method."
Is there a way to use a relay or something to do what the 3rd wire does?
Thanks again.
Yes, you would need a main control or timer to start the HRV and I don't know of any way to use the three wire interlock method on that model, but likely the two wire method will work fine.
Will give that a try... Thank you for your time and guidance.
Cheers!