New Furnace Problem - exhaust icing

[pdog15]

Had a new 2-stage furnace installed two years ago. Exhaust pipe goes through the foundation about 2’ above ground and extends about 2’ out. During these cold periods, moisture drips from the end of the exhaust to the ground as it should, but a column of ice builds up (about 3” in diameter. After a regular furnace inspection/filter change it has taken 12 days for the ice column to come within a half an inch of the exhaust pipe. A few more days and it probably starts blocking off the exhaust wth probably CO backup into the house.
So far the installer has offered no solution. Has anyone discovered a way(s) around this that works and can be relied on?

[ganderblaster]

Mine does that too. Keep an old ax nearby especially in these temps . Give the ice a whack every couple days. Not ideal but it works. Oddly last year was way worse then this one. This year just a small Icicle

[Twisted Canuck]

They all do that in cold weather. As mentioned, knock it down with an axe or whatever implement is handy. It's not really a big deal. If it were dangerous, the Code would change in a hurry.

[Dean2]

I knock it off too. One thing, if you let it build up too much, your furnace may refuse to run because it can't vent enough. I have seen that happen to two neighbours last winter.

[fishunter327]

Originally Posted by pdog15

Had a new 2-stage furnace installed two years ago. Exhaust pipe goes through the foundation about 2’ above ground and extends about 2’ out. During these cold periods, moisture drips from the end of the exhaust to the ground as it should, but a column of ice builds up (about 3” in diameter. After a regular furnace inspection/filter change it has taken 12 days for the ice column to come within a half an inch of the exhaust pipe. A few more days and it probably starts blocking off the exhaust wth probably CO backup into the house.
So far the installer has offered no solution. Has anyone discovered a way(s) around this that works and can be relied on?

Is there a 90 deg fitting on the end of the exhaust or does it vent straight out ?

[Big Grey Wolf]

When you shovel the walk knock it over with your snow shovel, part of 'preventive maintenance' these days.

[Arty]

Considering there's so much infinite and free electricity floating about that some people push cars around with it, just run the plastic pipe into a short section of electrically heated steel pipe. The hot metal should evaporate the few drops of water.

Of course that will consume more energy and materials than the little bit saved by not running a warm stack out through the roof, but such things never bothered the pointy-shoes eco crowd. After all, materials cost nothing and electricity is clean and therefore free.

Alternatively, maybe tee off the exhaust pipe before it punches out the wall so the drops fall down into an inside drain. Sort of like a water trap in a steam line.

Personally, I'd just use an old chunk of 2x4 or axe to smack over the stalagmite when doing the weekly walk-around house inspection. Beats the heck out of what they used to have to do with the frozen mountain under a biffy.

[buckbrush]

My wife uses an axe to chip it away once a week or so. I used to do it then she just took over one day. I think she just just likes weilding the axe??

I have had it build up and shut the furnace off a few times over the years. (Pretty sure CaberTosser diagnosed that one for me the first time I woke up to no heat)

[traderal]

My stacks are on the roof, I climb a ladder and use the long handle from my snow shovel to knock off the ice. If I wasn't around not sure the wife could do it.

[buckbrush]

Originally Posted by Arty

Beats the heck out of what they used to have to do with the frozen mountain under a biffy.

Ya, I think I would have just added a lift kit to the outhouse...

On That note I once saw a portajohn that had a frozen stalagmite sticking up higher than the seat and the Frac crew had resorted to squatting on the seat to add to it. Probably one of the most disturbing things I've seen in the patch...

[pdog15]

Appreciate your thoughts/comments. So far the toe of my work boot has worked ok. Problem would be if the house was vacant for any length of time. Will try a piece of plastic or tin at an angle on the ground to drain the drip away from the exhaust. The exhaust is pretty much parallel to the ground with a slight down slope.

[gunluvr]

Originally Posted by Arty

Alternatively, maybe tee off the exhaust pipe before it punches out the wall so the drops fall down into an inside drain. Sort of like a water trap in a steam line.

This would be a simple fix.
My neighbor has a big icicle below the exhaust outlet that forms from the ground up. Often, it grows nearly up to the pipe but never quite touches it because the warm air that escapes continuously melts the top of the icicle.

[vinny]

Please be extremely careful altering any type of venting. Improper venting or restrictions can cause a very dangerous situation with CO in your home. We get way too many CO calls this time of year. And they don’t all turn out ok. Clearing the ice is the safest method, or at least consult a professional before making any changes.

[58thecat]

Chop the ice down daily, or at least inspect it so nothing goes real bad.


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[Arty]

Originally Posted by vinny

Please be extremely careful altering any type of venting. Improper venting or restrictions can cause a very dangerous situation with CO in your home. We get way too many CO calls this time of year. And they don’t all turn out ok. Clearing the ice is the safest method, or at least consult a professional before making any changes.

So would HVAC draining into septic sewer be subject to plumbing code or HVAC code?

Seems to me it would be straight-forward to set up a tee off the fan-driven horizontal (cool) exhaust vent to drain condensate into a standard p-trap setup. Sewer gas is blocked as usual, and CO continues to be driven out the side of the house.

The danger would be not doing anything about ice buildup, thereby blocking exhaust with trace CO amounts from escaping. At least until any protective mechanisms trip the furnace completely.

I'd guess running plastic exhaust vents up an old chimney path would lead to all sorts of problems with condensate flooding and corroding the exhaust fan, so it has to be sent out through a wall. Arguably equally problematic is freezing the exhaust vent shut. I wonder how long it will be before ABC mandates a sewer tie-in for condensate...

[badbrass]

Originally Posted by pdog15

Appreciate your thoughts/comments. So far the toe of my work boot has worked ok. Problem would be if the house was vacant for any length of time. Will try a piece of plastic or tin at an angle on the ground to drain the drip away from the exhaust. The exhaust is pretty much parallel to the ground with a slight down slope.

And that's your problem! I also had a new furnace installed about 5 years ago.
When they are installing the pipes, one cold air and exhaust, i noticed that the pipes had a slight upward slant to them, and asked why they were installing them that way? He said I would thank him someday, as the little bit of moisture would go back into the furnace and not outside. This furnace has a drip pan, and as the furnace burns natural gas, and the moisture for the exhaust, the moisture then goes down a line into the floor drain. That's how they are to work correctly!
I have never had a problem at all with ice build up, or with the furnace!

[MK2750]

The exhaust pipe should be angled no less than 5 degrees towards the furnace. Do not drill any holes in the pipe as any condensation would run back to the furnace anyway.

Straight pipes cause problems. Creating a 90 degree angle up and then another 90 out away from the house is a procedure that generally eliminates a lot of issues. It also eliminates false trip out if a strong gust of wind blows in the pipe.

Code requires an exhaust be off the ground to avoid snow drifting and ice build up. Anything under 2 feet can give issues. The periscope method above helps with that issue as well.

The wrong sized pipe can cause venting issues in extreme cold, consult the installation manual.

Finally, the wrong size furnace can cause issues. Furnaces are more often than not oversized. A furnace that is too large for the duct system looses more heat out the exhaust. One would think this would melt the ice but in fact it moves the condensation process from indoors to outside. If the furnace was putting 95% plus up the duct system the exhaust gases would cool more in and around the furnace and the condensate would run down the drain instead of being blown out the pipe.

[Grizzly Adams1]

Originally Posted by vinny

Please be extremely careful altering any type of venting. Improper venting or restrictions can cause a very dangerous situation with CO in your home. We get way too many CO calls this time of year. And they don’t all turn out ok. Clearing the ice is the safest method, or at least consult a professional before making any changes.

X2, that post was a head shaker. That ice build up is normal, just deal with it.

Grizz

[urban rednek]

You say the furnace is 2 years old? Best make sure your furnace guy has the following parts available for you: flame sensor, ignitor, and high pressure limit switch.
IIRC- those are the 3 main components the manufacturers use for continual revenue generation.

[waldedw]

Mine in the garage does the same thing, it has for the 17 years I have lived here, I just knock it over with my ice scraper for the driveway, no big deal

[thumper]

On ours, a little water dripped down, but steam went up, condensing and freezing on the rain gutters and forming huge icicles that pulled the rain gutters off the roof.
We had to re-route the piping in the basement, to lead to the centre of the 'end' of the house where the outlet is well below the house eave.

[Battle Rat]

Originally Posted by pdog15

Appreciate your thoughts/comments. So far the toe of my work boot has worked ok. Problem would be if the house was vacant for any length of time. Will try a piece of plastic or tin at an angle on the ground to drain the drip away from the exhaust. The exhaust is pretty much parallel to the ground with a slight down slope.

Your solution will need a heat trace if you expect it not to freeze and pile up as it is expelled.

[Cold lake guy]

Journeyman plumber/gasfitter self employed
ALL furnace vents are to be graded 1/4 back towards thee furnace, if you have a single white pipe to the outside you need to snorkel the termination. A 90 straight up then a 6” pipe then a 45 elbow off that a short pipe cut at a 45 angle. Think of an rig exhaust pipe.

No sags in the pipe that will trap water, and again drain the pipe back towards the furnace

No more ice

[Cold lake guy]

Out the roof push a rag in, no plastic fillings inside. Cut at a 45, about 18 above roof line and insulate the pipe in the attic

Remove the rag

[Cold lake guy]

Oh ya put a heat trace on an empty pipe……read the label keep a fire extinguisher handy

[bat119]

Time to get the axe out for the shop vent