Why the condensate drain trap?
I'm having a high efficiency condensing furnace put in our second floor soon. We're going to insulate the condensate line but I'm wondering why the need for a trap? I understand why we do that in a toilet or sink, to keep sewer gases from backing up unto the house. But why a furnace (or A/C) condensate drain that drains out into the open (fresh) air. Seems to me that deleting the trap would eliminate the major freezing concern with a condensing furnace?
Okay, now why no cover on my drain trap?
Thrilled to have such a quick answer about the drain trap on a new efficient furnace. But it seemed so odd to have a cup of open water attached to the side of my furnace that I assumed the installer lost a cover. No, there is no cover. During the warm season it will evaporate; perhaps the owner is supposed to be educated to check and fill that trap each fall. Why would a cover be a bad thing?