Replies

1. 
   Shacko | Apr 22, 2010 12:43pm | #1

   Plumbing Vents

   "I would like to run all of my vents together in the attic space and have one vent penetration."

   Thats a common way of running vents when there isn't any structure problems......they are also run that way when the owner of  the dwelling wants them coming out of the back of the house instead of the front for looks.

   "Do I really have to worry about condensation freezing inside the vent pipes?"

   I don't see how the vents could freeze on the inside of the house; you would need to have the inside temperature 32deg. or lower. The only potential problem in cold climates is whats called HOAR frost which can appear on the inside of the vent pipe AFTER it penitrates the roof, some areas require the last 3ft or so to be one size larger then the vent terminal i.e. if your vent is 4in. you increase to 6in., you can do that whether it's required or not, you should be fine, luck.

   By the way if you are under UPC in your area you can run vents without any pitch at all, but they have to be level.

2. 
   rjw | Apr 22, 2010 01:01pm | #2

   FWIW, the local practice in my area is to simply nail the vent off just below a though roof vent (aka "turtle.")

   Having inspection 1000's of houses so done where there are no signs of problems (and thousands more done by other inspectors) I feelconfident it works, at least in NW Ohio's climate.

   Code enforcement could well be an issue.

   One local builder does what you are envisiing - it too works well.

1. 
   Clewless1 | Apr 23, 2010 08:42am | #5

   I've always thought it a bad idea to vent anything that isn't positively connected directly to the exterior of the roof ... exhaust fan ducts or plumbing vents. If the wind happens to be blowing in the 'turtle', you have a higher chance that the moist air will be allowed to condense on the nearest cold surface .... which would be just about everything (assuming it's winter and cold, of course).

1. 
   DanH | Apr 23, 2010 08:48am | #6

   It's certainly not a good idea.  Could cause condensation problems, could introduce odors/gas into the attic, etc.  A lot depends on the dynamics of the sewage system -- whether it "blows" or "sucks", and how much.

   Probably one of those things that you can get away with most of the time.

3. 
   rdesigns | Apr 22, 2010 03:24pm | #3

   Vents typically have a flow of warm, moist air flowing up and out, and it takes pretty severe cold to cause the moisture to freeze and close them off--and pretty severe cold is just what you get in north MN.

   If you're tying all the vents together, you probably ought to have 4" pipe for your final roof penetration, and the increase to 4" should be started at least 2 ft. below the roof. It wouldn't hurt to insulate the vents that are not already burried in insulation.

   For comparison, we get winter temps of -10 to -20 most winters, and have no problems with vents freezing closed, even in the smaller sizes. But I suspect 30 below or colder is not unusual where you live.

4. 
   DanH | Apr 22, 2010 07:36pm | #4

   I replied on you other post that it's common here in southern MN to tie everything together, and generally the horizontal runs are not below any insulation, either.  Never caused a problem for us and never heard of anyone else around here having a problem with this.

5. 
   KenLewie | Apr 23, 2010 07:55pm | #7

   Thanks Everyone

   All this great info has answered my question... I error on the side of caution if at all possible.  So I am useing a 4" roof penetration pipe connecet to a 3" main vent.  All smaller vents are submersed in blowin cellulose insulation and the short sections that are not will be wraped with fiberglass.  As far as getting cold here your right it does hit minus 30 on occasion and is just under a 10,000 heating degree day rating.  Why my parents decided to move back here to retire is beyond me, but they are hardy folk for sure!

6. 
   tinybutt | Apr 26, 2010 10:13am | #8

   plumbing vents

   I HAVE BEEN A PLUMBER IN NEWYORK CITY FOR 40 YEARS, THE PURPOSE OF VENT LINES IS TO KEEP THE SYSTEM IN YOUR HOUSE WORKING PROPERLY TO REMOVE ODORS AS WELL AS TO PREVENT SYPHONAGE OF TRAPS ON FIXTURES WITHIN THE HOUSE. A VENT MUST BE PITCHED SO IF ANY CONDENSATION FORMS IN THE PIPE IT RUNS BACK INTO THE SYSTEM AND IF YOU HAVE A MAJOR STOPPAGE THE WASTE AND WATER WILL EXPEL AFTER THE STOPPAGE IS CLEARED. IF YOU LIVE ANYWHERE BUT ESPECIALLY IN COLD WEATHER AREAS YOU MUST PENATRATE THE ROOF WITH A MINIMUN OF 3 INCH PIPE. THIS IS SO DURING THE WINTER MONTHS AN ICE DAM WILL NOT FORM OVER THE PIPE PREVENTING THE VENT SYSTEM TO WORK.  IF THIS PIPE WILL BE THE ONLY PENATRATION 4" SHOULD BE THE MINIMUN .

                                                                                                            GOOD LUCK