Originally Posted By: dvalley
This post was automatically imported from our archived forum.
Everything in the attic appears fine so far but I have more questions?
Are all the soffit vents unblocked from the loose fill insulation or are there baffles installed at this soffit area to allow outside air to enter?
What type of heating unit are you venting? Is it oil or gas? And how many floors is this vent going through?
Did you change your heating unit from a low/mid efficiency to a high efficiency? Low efficiency gas appliances such as older 78 percent AFUE furnaces/boilers rarely have such a condensate problem because the flue gas exits with a relatively high temperature making condensation difficult to occur. However, in your situation it sounds like you have a unit with efficiency just below 83% and the flue gas exits much cooler. These are known as category 1 type gas appliances and they are much more prone to developing unwanted condensation on B-vents.
This could also be caused from an excessive number of elbows installed. Can you figure out how many elbows are being utilized to vent this unit to the outside, from bsmt to attic? There should be no more than two elbows from the heating unit to the attic area.
How much B-vent is penetrating outside the roof surface?
I want to help you resolve your condensation problem but I need more definitive answers.
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