I noticed that there is significant heat loss at my bathtub drain. If I put my hand above the bathtub drain, I feel an icy draft.
The plumbing is directly under the bathroom, in an unfinished basement.
Here's what I have thought of so far:
Put a stopper in the bathtub when not bathing
Put foam sleeves around the pipes in the basement
Perhaps something in the plumbing arrangement in the basement needs to be re-done in some way
P.S. I chose "energy efficiency" as a tag because I couldn't find "heat loss."
Update: I nosed around downstairs while the hot water was running in the bathtub, so I could be sure I was looking at the correct pipe. There is a U a little below where the pipe comes out of the bathtub. Then there's a straight stretch of approximately 6 feet. Then there's a T and the upper part goes up and out of the house. That portion feels very cold. So apparently I feel a cold draft at the bathtub drain because cold air from outside is coming in through that pipe! Is that unorthodox?
Third update: I read about the "AAV" but wasn't sure if I was on the right track.
Then I read about what might be my situation:
Crawl under your bathroom to look at the drain assembly from underneath.
Patch the hole with pieces of foam board that’s cut to fit around the pipes. Screw them in place.
Then seal any gaps with spray foam insulation ($8 per can).