I have done this many times but never for a church. I have a church with a bad X13 out of warranty. I can use a PCS and relay and save them $$$. I can also use an evergreen X13 replacement which will cost them more. The drutter I face is the responsibility of modifying the OEM wiring and design. What are the opinions? The system is a heat pump and I can use two relays; one for cooling and one for heating. Right now I am inclined to use the Evergreen and sleep better.