Any HVAC experts?

[wingedfish]

Originally Posted by ILIKECOUGARS

Most heat/cool tstat have a build in jumper. so that when the stat is turning on the ac, the furnace fan turn on.

You need to add a relay to prevent the ac turning on when you run the HRV.

If your HRV ducts are connected to return air of the furnace then the furnace fan should run when the HRV is on.

exactly, when fan switch is in auto, y and g are jumped, this back feeds to turn on the AC. Common problem all Hvac guys run into.