re: Ac secondary drip pans have no drain…should they?

I don’t know code either but I’ve seen them both ways - my secondary only has the shut off float switch. With a drain line in the secondary pan one might not know if they have have a plugged up primary condensate line unless the secondary pan drain line is placed in highly trafficked visible location outside. First I’ve heard of a float switch failing, but obviously they can.

Let me pass on a tip from my plumber BIL, when in the attic check the water pans under water heaters or HVAC (if plumbed outside) for debris, usually pieces of attic insulation, and remove them, b/c he’s seen on multiple occasions where the emergency drain line became plugged with debris with a leak in a water heater and it overflowed the pan and caused ceiling damage even though set up to prevent that. I don’t know debris finds it way into those pans, but it does.