Rooftop High Efficiency Furnace Vents Frozen

Old 12-29-17, 03:29 PM
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Rooftop High Efficiency Furnace Vents Frozen

Hi All,

Looking for some advice, I have 2 high efficiency furnaces that are vented via the roof. The installer used the chimney stack becuase side vent was not possible. The intake has frozen shut on one of the furnaces (see attached picture). This is not a big issue as it was the upstairs furnace and, with the vaulted ceiling, we are still getting heat up from the main furnace and fireplace. So we are ok from a warmth perspective. Also I should mention that this is the first time this has happened in about 10 year (when we had them installed).

That said I would still like to have this fixed as it was a bit of a hassle.

A little more information, the storm that came in brought very cold temperatures, as low as -35 C with windchill. The storm has been 5 days and will last about another 2 days, after which the temperature will go to 0 and then +10 C. Yes we live in weird part of the world. Also the wind is from the the northwest which pushed the water vapors from the far right vent to the intake on the left side and I suspect that is what caused the ice build up.

I was thinking that a possible solution would be to add about 6 inches of piping to the intake vents to ensure the water vapors from the exhaust would be successfully blown away before getting to the air intake vents.

Does that sound like the right answer? Does anyone have a better answer?

Also to note is that part of the sleeve on the exhaust vents are missing. Likely due to Magpies in our area they have tendency of taking anything they can get there beaks on to make nests. Any suggestions as I suspect that this contributed to the problem.
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Old 12-30-17, 06:52 PM
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Join Date: Mar 2004
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The intake may be freezing due to precipitation being drawn into the pipe.

I do think your idea is worth trying regardless.

yes, weather this fall and early winter in north america has been weird.

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