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New HVAC unit now ICE at base of roof vent

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Cressidaadr

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Discussion starter · #1 ·
Last summer (2014) I had an all new A/C and forced air furnace installed. The contractor was recommended and seemed to be knowledgeable.

I noted during the winter months that there was ice forming at the base of my roof vent. This had never happened with my old unit in 25 years.




The new unit (a Goodman GME80603BN 80% 2 stage 60k BTU) was downsized by at least 1/3 in BTU output (because the old unit was too large and cycled quickly). One difference I noted was this new unit has a small blower motor to force the exhaust stream up the flue but my old furnace didn't have that. I wish the new one didn't have this blower because my guess is the exhaust air flow is moving too fast now and it seems to be bouncing off of the roof vent cap and condensing down onto the roof before freezing when it used to just ease out of the vent?

The contractor said the existing vent pipe did not need to be modified or replaced with this installation.

Would a new and taller roof vent (or different cap) help solve this or what are some other options that I should be looking for (if anything) to stop this ice formation at the vent base before we get into winter?
 
#2 ·
The flue gas is condensing ( and freezing) Looks like they did not replace the flue or cap-- Could be to large of flue I cant tell, but if that is Single Wall it is incorrect--- Personally we would have relocated it right above the furnace All New Flow Cap and Storm Collar

Your soon to have a rusted heat exchanger from that flue gas condensing

Just read your post from 2014 June- It was recommended then ( and again today) that the flue needs to be replaced Especially if that is Single Wall....Obvious no permit was pulled

Your contractor is Not Correct in his statement that the flue does not have to be replaced
 
#3 ·
Good lord man.
You'd think with all the threads you posted about this single, simple installation.....I mean, come on.

Flue is to big, and the flue is wrong type of pipe.

You went from a oversized 70% furnace to a smaller 80% furnace.
I'm surprised it drafts at all.
 
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#4 ·
So, what did you think of the previous advice? Expecting something different this time?

You chose an 80% furnace instead of a 90% because it was less cheaper.
You chose the cheapest brand.
You chose not to have the oversized vent pipe replaced because it was cheaper.
I see a pattern here. Only you can break the cycle.
 
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#5 ·
(removed duplicate post)
 
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Discussion starter · #9 ·
kdean1 said:
If there is he should be tarred and feathered.
Click to expand...
Yes local contractor. I believe it is 6" pipe but don't know if it is single or double wall.

Should it be replaced with 4" "B" vent - is that considered correct; or just ask another contractor and
hope that he agrees with all the experts here ?
 
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