Pro tip: that "universal" thermostat you got at the hardware store might not work on zone systems from the 90s

I spent 3 hours on a Saturday last month swapping out a Honeywell TH3110 for a customer's old Trane in their basement and the zone panel kept kicking the new unit into emergency heat until I manually jumped the B and O wires.

2 comments

2 Comments

schmidt.blake9h ago

Just read on a hvac forum that zone panels from the 90s use proprietary wiring that cheap stats can't handle.

noraj796h agoTop Commenter

Bet that's just what the stat installers want you to think.