This makes no sense.
Theres no need for a relay on the W circuit. If the wire was broken from the tstat then the relay wouldn't work either. If the W circuit was bad on the board then the relay wouldn't matter. Why ? Why? Why?
I repair air conditioners to keep people cool when it's 110+ degrees outside.
I repair heaters so people don't freeze to death.
I shut down furnaces that are unsafe to operate.
Make fun of my profession, but dang it, I save lives.
We're awl pawthetic and kweepy and can't get giwrls. That's why we fight wobots.