I'm trying to install a whole-home humidifier. I'm wondering whether I can use these copper pipes as supply lines for the humidifier. Any guesses as to what pipes A, B, and (just out of curiosity) C do? I believe they're connected to a condensate drain, but am wondering where they come from.
A and B look to be a gas line of one nature or another, whether it be natural gas or liquid propane (LP), C is the conduit that feeds electric to the unit.
Either A or B supplies the unit, and the other branches off to supply fuel for another appliance that requires gas.