Any HVAC experts?

[wingedfish]

Originally Posted by weyburnt

So if this is the case than why would the thermostat have a Y and a G if both points are common to each other, what is the point in having 2.

It is a long history lesson involving the the dawn of AC and single speed belted fans. Coles notes: the thermostat operator can choose to run the fan or AC. This is important today because with ECM motors, it is advantageous to run the fan.

Originally Posted by weyburnt

So the OP could change his thermostat out for a new one, and keep his wiring exactly the way it is now

No because, as you stated a few posts back, he would not be able to set the stat to cool and auto.

Originally Posted by weyburnt

or, if there is a spare conductor between the furnace board and the HRV, than he can use the diagram at URL and connect the unit using Alternate Furnace Interlock wiring. but in no case will he need a relay added

Look closer at that diagram, "NC C NO" stands for relay and this brand of HRV has one built in. Therefore, he does need the relay. The HRV may have one though.