I have a problem with my plumbing vents on the roof frosting closed when the temp is cold and the wind blows across them. Anybody have a solution to this problem?
I should add, this is a early 80’s built split entry, 1000sf per floor
Cousin might have answer? The best solution is to change the roof cap to a frost free type. It is a galvanized pipe cover with a lead ring on the end to seal around the pvc pipe. This helps to trap the escaping heat and use it to keep the pipe open. That said, it needs to be warmer to install without wrecking shingles and being able re-seal it all up after install. But I think Home Depot/Fleet Farm or plumbing shop has one that inserts into the vent pipe that is there now so you would not need to pull up shingles in the cold to install now.
See what the plumbers say about the “frost free” vent system?
I’m not sure what they are called, but we nicknamed them bird houses. They are about a foot tall, 8 inches in diameter and made of black plastic with rigid foam on the inside, they just slip over the pipe. I used to have to buy them at a plumbing wholesale store but I think menards started carrying them.
Have heard of frozen vents but never gotten a call to fix one. maybe try painting the vents black to get warmed by the sun. Wonder if the vent pipe are to high above the roof the sewer gasses might cool to much before the end of the pipe. Or maybe just the opposite are they to short and getting snow covered. Are they causing you problems with the toilet not wanting to flush and drain not working properly? Have heard about putting a copper pipe in the vent but have no idea how or why that would work. Not sure about steves idea either ov changing out the flashing. It might work but no idea why it would.
Plumbing code here calls for a pipe of atleast 1 1/2″ inside dia. that goes to within a foot of the roof in the attic, then flares to a 3″ so frost buildup doesn’t close the vent pipe, this is new construction or remodeling. It wouldn’t hurt to put a bigger pipe from the roof line up. When it warms up then Id go with the new construction code so you can apply the roof fitting to make the pipe waterproof, it seems to solve the problem here in Iowa.
There is no draining problem. The problem is the smell, we get sewer gas that collects in the entry way. Could not having enough attic insulation cause this?
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Plumbing code here calls for a pipe of atleast 1 1/2″ inside dia. that goes to within a foot of the roof in the attic, then flares to a 3″ so frost buildup doesn’t close the vent pipe, this is new construction or remodeling. It wouldn’t hurt to put a bigger pipe from the roof line up. When it warms up then Id go with the new construction code so you can apply the roof fitting to make the pipe waterproof, it seems to solve the problem here in Iowa.
Very similar here in WI also. My plumbers take a 2″ vent up then go to 3″ well below the roof penetration. Any snow accumulation in the pipe generally melts since the transition is in the “heat loss” zone of the attic.
If your able to access the vent safely, pour some biodegradable RV Anti-freeze down the vent tube. That will melt out any current freezing you have. Obviously, you need a long term solution and I would look at changing the vent size if feasible.
As for a reference, here is link to WI code SPS 382.31 Venting
It is frosting up/closed above the roof line only. I use a broom stick and push the frost/ice down the vent and all is good for a few days, until the temperature drops and the wind blows. I think I am going to try some type of “T” on top of the vent and see if changing the air flow over the vent will work.
So what is the sewer gas coming from. Traps dry out this time of year and need water added to them. If its a open pipe it needs to be sealed. Clogged roof vents will cause traps to get sucked dry to. Was reading about putting a couple of street 90s on the end of the vents to try to hold the heat in.
Thanks for the replies. I had some 3″ galvanized dryer vent that I cut 2 inches above the vent pipe and painted them black. I put them over the vent pipe, we will see if that helps. As far as liquid in the traps, I try to keep them full by running water every once in a while, looks like it will be at least weekly.
I had this problem on my brand new house. All 3 of my plumbing vents were froze over. Friday night had a bad smell in the master bedroom, and notice that when flushing one toilet the other on that same line would drain down. Also found that trap on the sink to be getting sucked down enough to allow gas to pass through.
I had to go up on the roof yesterday and open them up. The builder is going to ask around for solutions, but I am going to try to paint them black as well. My stacks are 3″ and 4″, and I think the third may be a 2″. The 4″ was at or below the snow line on the roof so I think it need to be extended, but the other two were at least 8″ or so above the snow line.
I see the new house being built next door to me has snow on one of their vent lines….so I think theirs is plugged as well.
Just got a call this morning for someone having these issues. Not sure what Ill find or what we are going to do about it. Kinda hoping with any luck the warmer temps this week thaw the pipes out and everything goes back to normal.
I used to have that problem with the pvc vents freezing up in cold weather. It was the moist air being vented that would freeze up.
I had the lead tops installed when my roof was replaced and have not had an issue since.
Good Luck
Steve
so far so good with using the galvanized dryer vent painted black. I will give it till the next cold snap before I give that fix a thumbs up. I am optimistic that it will work.
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I used to have that problem with the pvc vents freezing up in cold weather. It was the moist air being vented that would freeze up.
I had the lead tops installed when my roof was replaced and have not had an issue since.Good Luck
Steve
Any idea why these types of vents would make a difference?
Just got my second call of the day about frozen vents. Never a call on them in 25 years and now two in one day. You guys have started something. 
Mike, My theory would be if they wrapped the PVC pipe with lead and folded the top over into the PVC, you reduce the diameter and increase the pressure of gas rising out. One way to combat it I guess. I would still question why they would freeze to begin with. I understand older homes before (common sense) codes were applied. But in newer construction, if the envelope is sealed/vented properly, this shouldn’t happen. BTW, congrats on the new segment of business Mike!
I have found that the vents that freeze are normaly on the north/northwest side of the homes/and are then more exposed to the cold air.
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But in newer construction, if the envelope is sealed/vented properly, this shouldn’t happen.
Randy, how you think the envelope would play into this?
My vents are both on the west side of the house, one on the north end and two on the south end. One was more or less burried, so I see how that could happen. Still not sure on the other two and how this actually occurs.
They was fairly solid 1/2″ ice on the interior surfaces of the pipe, over the whole section that was above the roof line. Inside of that was more crusty snow. I wonder if the cold weather combined with all the light snows and higher winds have cause the snow to start sticking to the ice and building up slowly over time. It just has not had time to really melt and it slowly builds up?
my theory is, the cold wind blowing over the top of the pipe causes turbulence at the outlet because the wind is stronger than the air venting out the pipe. the air in the pipe is warm and moist, and the wind is dry and cold, frost builds up until the pipe is frosted shut. after time, the frost melts and turns to ice and builds up on the inside of the pipe above the roofline..
Randy, how you think the envelope would play into this?
In some engineering formulas used, venting accounts for a heat loss factor. I don’t recall what it was, and I couldn’t find it. I’ve seen them full of snow, plugged from birds/critters, but never frosted shut unless they were sized wrong
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Randy, how you think the envelope would play into this?
In some engineering formulas used, venting accounts for a heat loss factor. I don’t recall what it was, and I couldn’t find it. I’ve seen them full of snow, plugged from birds/critters, but never frosted shut unless they were sized wrong
The problems I have seen are mostly new home construction typically, you will find two or more vents on a roof, one of which is 3″-4″ this is the main sewer vent, and the others are 2″ vents that meet the MN state code. 2” PVC vents can freeze when they are exposed to the NW winter wind as mentioned before. What I have found when this occurs is, test caps which are glued into vent piping above the roof have been not removed. When this happens the 2” vent is left to vent the home. During the winter months this can freeze easily, and when the warm air from the sewer is exposed to the cold air and winds of winter it can frost over.
There are two things that a properly vented plumbing system provides to your home, it allows the sewer gases to be vented into the atmosphere, and at the same time draws air into the system when your fixtures are draining, which prevents your traps from siphoning and allowing sewer gas into your home.
So if you are having problems with sewer gas entering your home, you need to check all vent penetrations on the roof.
And like Randy stated it is not uncommon to have a bird’s nest or even a bird blocking one of your plumbing vents. One think to watch for during the winter is that you will see birds sitting on the top of your vent piping during the winter, the reason they are there is the warm air coming out of the vent.
I have 3 vents on my house (all were froze over), and my house is kind of split into two zones. On one side of the house is one zone which has master bath, main bath, and laundry. This has it’s own 3-4″ vent which was completely frozen over. After I opened it up it started venting right away….could easily smell it!
The other zone is on the other side of the house and mainly includes the kitchen and dishwasher, the mechanical room is over there as well so any venting that might be coming from there. I have two vents on that side of the house, one is a 2″ the other is a 4″. Both of these were frozen over as well. Once I opened them up both started venting right away. None of these vent were blocked with anything, other than the frost/ice/snow.
The 4″ does sit a little to low I think…and was even with the snow line so that might be the issue there.
House is 7 months old.
***update***
the galvanized dryer vent painted black slipped over the pvc pipe is working great. We have had cold temps and wind and no sewer smell in the house. This tells me that the plumbing vents are open and working as they should. Cheap and easy fix
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***update***
the galvanized dryer vent painted black slipped over the pvc pipe is working great. We have had cold temps and wind and no sewer smell in the house. This tells me that the plumbing vents are open and working as they should. Cheap and easy fix
Good to know, but I’m not sure it has been cold enough long enough for them to plug up? It was 18* yesterday…..I think if it holds up over the next week that will be a good sign. Curios to know….I will be watching mine this week to see if they freeze up again.
Looks like the vent on the bedroom side of my house is frozen as of tonight. I need to get this resolved…..time to call the builder.
Got an image of the dryer vent setup you used on yours?
-24 this morning and all is well with the plumbing vents. I will say the bigger diameter dryer vent over the PVC works in my situation.
I finally got up on the roof and found all my vents frosted shut. One 2″ and two 3″. I wrapped the exterior of them tight in black plastic and taped them up good. Hoping the sun will warm them enough to keep them open going forward.
Still don’t understand why this is happening on a new house when others don’t seem to have the issue. I have another call into the builder.
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