Best way to implement HRV control

I’m not very new to Hubitat, but till now all my uses of it were relatively simple.

I was wondering what the best way would be (if possible, at all) to improve control my HRV system.

Currently my HRV (heat recovery ventilator system) is connected to Hubitat and runs for 20 minutes every hour. Its all done using rule machine. Nothing fancy just every hour from X:00 till X:20. In addition to this HRV I’m using Ecobee to control my Furnace/AC. When HRV is ON its running the furnace FAN

The problem is that in many cases HRV and Furnace are running at different times. For example, the HRV can run from 9:00 till 9:20 and the furnace can run at 9:30 till 9:45

I want to minimize the run time of the furnace fan while still running the HRV for 20 min every hour. If the furnace is running anyway, I want Hubitat to run HRV too as long as HRV was running less than 20 min during the last hour. Or something like that.

I can create a variable and using rule machine check every minute if the if the HRV is running. If it is it will add 1 to the variable. This way I will have a counter of the HRV run time per hour. These variables can be reset every hour. Same rule that runs every minute can check if Furnace is running and my counter is less than 20 min it will run the HRV until the counter reach 20.

I guess it will work. But its not a very elegant solution and I'm not sure how much load on the hub it will create because it does it every minute.

Not sure this answer will help you, but I use the Honeywell Home THM5421R1021 IAQ Equipment Interface Module. You may also want to check your ASHRAE Standards 62.1 and 62.2 for ventilation rates etc. My HVAC (but not my ERV) can be controlled with HE and Alexa. But I was not familiar enough with the IAQ module to set it up. I had to have a professional do that one.

Yes I'm actually aware of Honeywell IAQ. Its the only thermostat that I know about that can control the HRV, Furnace, Humidifier etc. Its nice, but relatively old, expensive and complicated to setup. Plus I like my Ecobee setup and prefer to stay with it.

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