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Snow blocks furnace intake

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  • Jan 19th, 2009 10:59 am
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Jr. Member
Mar 18, 2007
112 posts

Snow blocks furnace intake

Just moved into a new house and am having some difficulties with the furnace. It is a 4yr old high efficiency furnace with two pipes going through the wall to the outside. One is intake and the other is exhaust. The problem is that the intake is getting blocked up with snow even in very light snowfalls. When the furnace can't suck in sufficient air it automatically shuts off. The furnace keeps trying to turn on but then shuts itself off without ever producing any heat. I have to go out with the shopvac and suck out the blockage in order get the furnace going. We have to go away for a week over christmas and I am very worried about the temperature dropping dramatically in the house. Any ideas on how can I prevent the intake from getting blocked?

The intake pipe is a sort of upside down J shape with the actual intake facing down. You'd think this would be sufficient to prevent snow from accumulating inside it, but somehow it keeps getting in there.

Any help is much appreciated
38 replies
Deal Addict
User avatar
Jul 19, 2006
2208 posts
87 upvotes
Toronto
we have the same problem this year during the big storm...never had this problem before...I think I will install a mesh-like cover for it next year...our problem is not serious enough yet...i think...

anyway...what I did was just shovel all of the snow away from the pipes...I think it helped...
[OP]
Jr. Member
Mar 18, 2007
112 posts
I can see how this problem might be expected when there is a very heavy snowfall, especially if you don't clear the snow from the area around the pipe. But like I said it is happening to us even after very very light snowfalls. I have also cleared all the snow away within 5 feet of the pipe.
Jr. Member
Nov 20, 2005
121 posts
Oakville
I have the same problem as the pipes in my house sit about 18" above the ground, currently I'm shoveling around them to keep things running.

As goofy as it may look you may want to grab some wood scraps and make a box to sit around/on top of the pipes. I'd make the top solid (to prevent the snow from going through, and put angled slats on the side with good sized gaps for airflow. As long as the box is taller than the snow it should still be able to breathe sufficiently.
Deal Expert
User avatar
Jun 3, 2005
26828 posts
403 upvotes
Ottawa
what a strange problem.


it seems the only solution is a series of filters. Some INSIDE the actual intake pipe...some outside. The box is a natural solution of course...but really..if even LIGHT snowfalls causes stoppages....how effective would a box be? Unless the box is really constructed securely enough.
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Deal Fanatic
Jan 16, 2003
6202 posts
75 upvotes
Try to figure out a way to deflect air around the intake. I doubt that it's sucking the snow from the ground, I think that it's sucking the snow in when it's windy. If you just box it or put a sheet of wood / plastic in a key location to deflect wind it might be enough to take care of the problem.
Member
Oct 20, 2003
364 posts
1 upvote
Waterloo
While I don't have this problem in my house, I have seen what some others have done to solve this. It's actually quite easy.

The 2 plastic pipes come out parallel to the ground and instead of leaving it at that, you put a 90 degree elbow upwards and extend the pipe 12"-24" vertically and then put a 180 degree elbow on that with a short 4" downpipe. This raises the level of the intake and exhaust avoiding the snow issue.

Hope this helps.
Deal Addict
User avatar
Nov 16, 2003
2581 posts
22 upvotes
Toronto
We had this happen to us last winter, not due to snow. After we stucco the outside of our house, the pipes were not extended, it currently has a 90 degree pointing to ground, and about 1/3 of it was blocked by the stucco increase of 2" thickness to exterior wall. the guys who did it didn't cut the stucco to keep it open. the furnace guy came and acutally unscrewed another opening in the furnace. open up your furnace, and look at the intake, usually there is a T shaped pipe, it can either suck air from the outside, or the inside, after unscrewing the other end it's sucking from both in and out now, and the problem never came back.
Sr. Member
Jul 21, 2006
653 posts
5 upvotes
virgoan wrote:
Dec 19th, 2007 12:56 am
we have the same problem this year during the big storm...never had this problem before...I think I will install a mesh-like cover for it next year...our problem is not serious enough yet...i think...

anyway...what I did was just shovel all of the snow away from the pipes...I think it helped...

This may also cause you problems. We have a high efficiency furnance as well (96 UAFE), the installer said never to put mesh on the intake for this furnace as it will reduce the air rate and cause the furnace to think it is "under water" which will cause it to trip and not function.

Jay
Deal Addict
User avatar
Nov 23, 2001
4486 posts
58 upvotes
Calgary
All furnace intakes should have a wire mesh of some sort on them. How else would one prevent a squirrel from running inside. Believe you me, I've seen plenty of rodents try to chew through a metal mesh to get to a warm spot in the middle of winter.

If its restriciting the airflow, you need to get a bigger intake. Just like a vaccum, the smaller the intake is the more powerful suction you get, causing leaves and snow to be sucked in. If you spread out the intake into a larger orifice, the suction will not be as strong but you will get the same amount of air.
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Deal Addict
Sep 11, 2006
1918 posts
9 upvotes
KELOWNA
This may be totally off base but I'll put it out there anyway. It's crossed my mind after having a furnace guy tell me to do this with the air vent that blows into the basement. Anyway, in one house it was just a vent blowing out from the furnace to the floor which caused a lot of draft. He put a bucket under it. New furnaces have a cage on them now which helps stop that draft. All it did was change the air flow and have it disburse differently, but it was simple and it worked.

So for the intake, I can't see why it wouldn't work as long as enough air was getting in. If you can imagine hanging a big bucket or ice cream pail from your intake so the actual opening to the vent is in the bucket (but not touching the bottom). If the bucket is large enough, it's basically shielding the vent but still allowing it to operate as air can freely flow through the top of the bucket and into the vent. If it's windy etc, the sides of the bucket should prevent snow from blowing up that vent although I guess the problem is whether you need to somehow put a 'roof' over it to prevent falling snow from going into the bucket. I really can't see mesh keeping snow out but if you can rig something solid that still allows airflow...

Or... call a local furnace company and see if they have some sort of solution you can just attach to the vent/house. You can't be the only person whose had this problem.
[OP]
Jr. Member
Mar 18, 2007
112 posts
hotgo wrote:
Dec 19th, 2007 9:19 am
While I don't have this problem in my house, I have seen what some others have done to solve this. It's actually quite easy.

The 2 plastic pipes come out parallel to the ground and instead of leaving it at that, you put a 90 degree elbow upwards and extend the pipe 12"-24" vertically and then put a 180 degree elbow on that with a short 4" downpipe. This raises the level of the intake and exhaust avoiding the snow issue.

Hope this helps.
my intake pipe does exactly this... It is not a problem of getting blocked by snow that has fallen on the ground. It is sucking snow out of the air as it falls and this is what is leading to the blockage.
Deal Addict
Jan 11, 2007
1148 posts
73 upvotes
Brampton
Perhaps it is the snorkel (upside down 'j') on the intake that is causing the problem. The snorkel is to increase the distance from the exhaust, so the furnace doesn't suck in exhaust gases. But if the snow is getting sucked in and sticking to the sides of the pipe without melting, it could accumulate in the snorkel.

I would contact the manufacturer of the furnace to see what your options could be to re-configure the piping or their terminations so this isn't an issue.
Deal Addict
User avatar
Nov 23, 2001
4486 posts
58 upvotes
Calgary
There is also a chance that your furnace not turning on has nothing to do with the snow blockage.

If the air intake is too cold, and your air temperature sensor is not set properly, what can happen is this:

The furnace turns on, the gas turn on and heats up the furnace block. The fan attempts to turn on (usually indicated by a buzz) - but will not because the temperature sensor is still too cold (IE: its too close to the fresh air intake) The furnace block continues to heat up, and without the fan moving, the main overheating failsafe for the furnace block will trip and shut down the whole furnace.

If you get the same furnace problems on a really cold day without snow, this may be your problem.
A US nickel is worth more than 5 cents.
Newbie
Feb 11, 2008
1 posts
Vaughan, Ontario
I am also having the same problem. I have two furnaces, air intake pipes protrude from the same wall approx. 4 ft. apart. One has a 90 degree bend pointing downwards, the other points straight out of the wall. The furnace with the intake having the 90 degree bend continuously clogs with snow during a windy snow fall. The intake that sticks straight out doesn't clog. I am very confused by this?

I think the post that suggested hanging the bucket from the intake pipe may work. However, I would drill holes at the bottom of the bucket to let any snow accumulation fall through.

Therefore two suggestions, 1) Take the 90 degree bend off the intake and let it stick straight out -- I'm not sure why this works but if it works for you ... who cares why.

2) try hanging the bucket from the intake pipe.
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