Can two furnace condensate drain pipes be joined into one?

Question

For some reason the Ducane furnace installed in my top floor has two 3/4" PVC condensate drain pipes coming out of it. (No, I'm not confusing them with the 2" intake and exhaust pipes.) I've traced both pipes and they go all the way down to the basement drain. I'm finishing my basement and need to reroute these pipes. But, I don't see any reason to maintain two separate pipes. Is anyone aware why the builder would have put in two separate drain pipes, side by side?

Answer 1

You bet. The two condensate lines are not pressurized. One pipe drains the coil and the second drains the heat exchanger. Both pipes work by gravity. No current hvac code prohibits what you want to do. Just remenber to inspect your new single pipe once in awhile to make sure there's no obstructions. Easy.

Answer 2

That seems strange.  Maybe one pipe is actually a listening device

Answer 3

What Giz said. I always run my furnace and AC drains seperate, but tee them together at floor level. There is no code in my state that requires me to do it, I do it because it gives me twice the chance for successful draining of my systems.

Answer 4

The furnace could have been replaced. Do you know if both were installed at the same time? Having the two actually makes things more efficient. Joining the two may end up as a hazard on account of the pressure that may be built up. With the two pipes, pressure and heat energy is divided and things are much safer.

Answer 5

Could one of the drains be for the A/C evaporator coil?

Local codes may require them to be separate.

Combining drains from different sources could cause a problem with draining properly as they may be at different pressures.