Quote:
Originally Posted by where2
I like page 18 and 19 of that manual...
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Agreed. I have pretty much memorized those pages. And also pages 13 and 14 that give a nice walk through of the control logic. What they don't show is that the control relays are on a printed circuit board and are controlled by a microcontroller. And that control signals are sent from a different microcontroller in the wall control unit. So I know which relays need to be energized and when, but I don't know the secret handshake to give the signal wires to make it happen.
If all I wanted to do was run the HRV at high speed using the dehumidifier function from the Nest, I could just wire a 24vac relay backwards to the interlock pins. But that won't get me to a low speed programmable timed interval which is actually the more important of the two features. I could also use relays and splice into the 120vac wires to control the fan and damper directly. But that would likely result in the unit freezing up because the damper was being held open when it should be closed for defrosting. It's also nicer to work on the low voltage side if possible.
When I started out, I honestly thought this would be a 15 minute job of installing two relays.