Monday, December 14, 2009
Frozen Vent Pipes Can Cause Sewer Gas Smells.
Question: When the weather is below freezing I get a sewer smell in the house. One plumber came over and poured hot water down a pipe on the roof and it immediately unplugged the pipe and the smell went away until it froze again which it can do the next day if there is a cold spell. I can’t be getting up on the roof everyday for weeks at a time to do this. There must be a better solution. This plumber didn't know what to do so I made some calls and another plumber told me to put an external heat tape like the one gets put on the roof to keep the snow melted down this pipe. I am going to try it. I was wondering if anyone has had this problem before and what their solution was.
Answer: In most venues the minimum sized vent pipe is 1" diameter (that’s with a minimum number of fixtures that its venting), this minimum sized vent needs to penetrate the roof and must extend a minimum of 18", no greater than 24" above the roof . All these rules are to allow the gases to escape well up in the air above the house and to prevent the roof vent from becoming blocked by hoarfrost (basically the same white, icy frost you'll find in a freezer. If, after all that, you still have a roof vent that's susceptible to hoarfrost, they tell you to increase its size one pipe diameter (i.e. - from 2" to 3") - which could mean having to replace the roof flange, as well. Find out what the code is in your area, and determine if your current installation meets that code. Additionally the most common vent problem that we run across is a clogged vent which causes toilets to gurgle and drains to run slow. Water can also build up at the clog and eventually can cause an ice blockage of the vent pipe thus not only would you have the sewer gas type smell to build up but slow running drains as well.
This is proof that you can teach an old dog (that’s me) new tricks. Having been raised in the South I didn't even know what hoarfrost was. Do you mean it's not a cold woman of the streets? Also rarely does it get cold long enough to cause this type of build up, but we do experience frozen vent pipes temporarily during ice storms or particularly cold weather. Normally this clears up sooner than we can realize that the problem exists. As always, I hope this new solution will be also help to you. Comments and stories about your own problems and solutions are always welcomed. Use the search device on my blog (upper righ corner) to find all of the blogs I have written amount "whats that smell". I smell a book coming on!