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Heating, Air Conditioning, Fridge, HVAC/water dripping from a furnace gas vent


I have an Armstrong Ultra 80 SX high efficiency furnace with a simpson Duravent Class B gas vent coming out of it. There is a little bit of water dripping out of the gas vent at one of the joints. My question is why is this happening and how serious of a problem is it? Is it something that i can repair by just putting on a little bit of a sealant or do I need to replace the whole vent line (or worse)? Is there a chance that it's also leaking gas and that I'm risking poisoning myself? so far the furnace is still working just fine but I'm worried that this might be causing it some damage.
Thanks for your help.

Hi William, What your seeing is combustion air condensate, which is normal. But it's not normal to see it leaking at the joint. I would seal it with Hi-temp sealant all the way around the joint. Do you see any rust? Make sure you have a CO detector in your house.

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Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

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