Condensate line gurgling

[Rick Healy]

I inspected a furnace (Lennox Pulse 21). The condensate line is plumbed with 1/2" CPVC pipe. There is a standpipe made, and when the furnace is running, there is a gurgling sound coming from this pipe? Any thoughts on the cause, or problem?

[David Bell]

No trap or dry trap. Pulse furnaces also tend to fill up with rust in the pvc vent pipe trap. IMHO one of the biggest pieces of crap ever put on the market.

[Jerry Peck]

No trap or dry trap.

Or insufficient trap seal depth for the static pressure in the unit?


The condensate line is plumbed with 1/2" CPVC pipe.


I thought that 3/4" was the minimum pipe size for condensate lines? I know it is for evaporator coils, do those units allow for smaller condensate drain lines?