Why is there water leaking from the intake & exhaust pipes of my HE furnace?

Question

My high efficiency furnace was installed this summer, so the furnace has only been operating for a month. But recently, I realized at the place where the intake and exhaust pipes connect with the furnace, there's water sits on top of the furnace. And as the water evaporated, there's white water marks left.
Does anyone know what's causing this water leaks?

Answer 1

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HE furnaces make huge amounts of water - it's a combustion byproduct. I had one with it's condensate drain run into a 5 gallon bucket and on cold days it would fill the bucket in 5 or 6 hours. Most of the condensate is collected in the heat exchanger and these furnaces have tubes and pipes to collect this condensate and carry it outdoors on the ground. IN most municipalities it is not legal to run it into the sewer (it is very clean, maybe slightly acidic water - the treatment plant just doesn't need to waste energy processing it).

Some condensate will condense out on the walls of the exhaust pipe. This is typically 2.5" PVC pipe. The joints are supposed to be glued and the pipe is supposed to be sealed at the top of the furnace with a rubber gasket. This water runs back to the furnace and into the condensate collection system. It sounds like maybe yours isn't sealed correctly. I'd be more concerned about the carbon monoxide hazard than the leaking condensate....

Answer 2

its from the the water vapor that condednses from the flue gases as they cool going up the flue. perfectly normally, however the water shouldn't be leaking onto the top of the unit. The contractor must have forgot to seal something

Answer 3

Check the flue pipe sizing chart that came with the unit, sounds like you may be undersized for the length of the run and number of elbows. You may be restricting the flue gas causing an abnormal amount of condensation.

Source(s):

http://www.furnacepartsonline4u.com