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I've been reading the great responses to prior threads about interlocking a HRV with the furnace blower and tying in with an Ecobee. Haven't found exactly our scenario in previous threads, so I'm hoping for advice.

We have a new Mitsubishi Zuba central heat pump wired to a PAR-40MAAU thermostat. We also have a Vanee 190H HRV that came with the house, but which we haven't actually used in >10y living here. It's been cleaned, and I just bought a bronze controller which I installed today to be able to control it without having to go into the crawl space to turn on/change speeds on the HRV. It is set up to exhaust air from a return trunk and to put fresh air into the main supply trunk. The manual says that it doesn't require the air handler to be running with this style of install, but I imagine it will work more efficiently if it does.

Our heat pump installer had initially said that we should be able to interlock the air handler to run when the HRV is on, but I'm not sure that's the case. It looks like the air handler is only set up to turn off the HRV if it's in defrost mode rather than being turned on itself by the interlock relay when the HRV is running. If they were to try to link the two, I think I understand that we'd be stuck choosing either low or high fan speed for the HRV?

Is anyone familiar with this kind of setup? Would it possibly work, or should I just resign myself to the air handler running as needed and the HRV doing its own thing independently?


 

What is the air handler model number?

Sorry, I only now saw your reply. It's PVA-A36AA7.

I don't think the Venmar Part 12658 is compatible with that system.  It relies on a 24V source from an air handler or furnace.  The air handler will control the interlocking anyway.

You likely need Part PAC-740, from Mitsubishi.

Disconnect the HRV main control B and G wires from the HRV. I suspect you can keep the other wires connected so that the main control LED still functions.

You would use Part CN24RELAYKITCM3 to connect the air handler CN2C connector to the HRV B and G terminals.

Then use Part PAC-740 to connect the air handler CNER connector to the HRV main control B and G wires.

I believe closing the B and G terminals activates the HRV high-speed fan.

Only seeing this much after your reply, but thank you so much for your thoughts. I'll investigate this further!