drain trap linkage to combat sewer gas
hi folks. i have a garage underneath a bathroom and an adjacent light well. this bathroom has an intermittent problem with sewer gas smell, and at least one of the causes is that the drain in the light well dries up in a few weeks without rain. right now, if i smell the sewer gas, i have to open an ancient wooden window into the light well and run a hose to refill the trap (the iron one shown below).
i had some plans to add an irrigation line here, but looking at the plumbing from the garage beneath, i think i have a better idea: to add a small tube between the shower and the exterior drain traps. this way, whenever someone takes a shower, enough (grey)water would flow laterally to keep the drain trap full. it would require maybe a bulkhead fitting in the copper trap and a NPT threaded one in the iron trap. hopefully the attached photo makes this clear (please ignore the messy light fixture in the middle).
my question: is this scheme crazy?
Replies
hey there-
im not a plumber; just my two cents- id either install a trap primer off your bathroom supply pipe somewhere, or open the window and throw a bucket of water into the light well every satuday afternoon. also, plumbers have been known to put mineral oil in traps that are prone to drying out, doesnt dry out. im assuming that would most likely get washed away by a significant rain storm, but....
Don't check valves also block sewer gas?
If so, maybe all you need is an in-line check valve.
thanks mikedrums, i had not understood what kind of check valve you meant. i found some related hardware discussed at
http://www.buellinspections.com/your-plumbing-system-should-not-pass-gas-indoors/. either of these look like installing them would mean replacing the cast iron trap.
thanks for that tip, indeed the term of art is "priming". i want to keep the trap primed. i'm not sure why this would justify using a valve, or what would reasonbly trigger the valve to open. that is essentially similar to the irrigation line solution, where the valve is controlled by a timer.
I think they call them wet drains. I always figured they would be expensive as teh drain has to have a water line plumbed to them and some kind of valve, and or timer. $$$$$$$$$$$$$$$$$$$$$$$$$ I always figure that a cup of water once a month would work., of course that would be a pain. SO $$$$$$$$$$$$ or bother?
For some styles of floor drains there is a sort of float valve (consists of a hollow ball and a threaded collar) that can be installed from the top. This will effectively prevent evaporation. The valves have a tendency to stick closed, however.