Gas and Oil Home Heating Furnaces - Venting advice for 90% furnace

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crv16
08-24-04, 12:15 PM
Hi All,

I'm replacing an old 50,000 btu 80% efficiency furnace with a new Goodman GMNT060-3 60,000 btu 92.6% efficiency furnace.

The new furnace vents via 2" pvc. The furnace is in a (two car under) garage. I could poke a hole in the sidewall for a vent, however the other side of that sidewall is (lattice vented) crawlspace under a covered porch. Seems like a no-no as far as code is concerned. Other sidewall locations are problematic due to aesthetic objections (front and side), and other back locations are difficult due to need to rip into finished basement walls & ceilings.

Can I just run 2" pvc all the way up the old chimney flue? It would go up about 24 feet. I've seen suggestions from people that it needs to be insulated to keep from freezing. Has anyone had experience with this? Thanks for the advice and comments!


mattison
08-25-04, 05:46 AM
I've seen it done but would check with the manufacture 1st. Where are you getting combustion air from? If you run it out the "good" sidewall you can paint the pvc to match the house. One of the problems I saw once with venting it out the chimney was that the condensation coming out froze over the top of the chimney.

crv16
08-25-04, 06:39 AM
I was going to get combustion air from under the porch. There's a few feet of crawl space under the lattice vented porch. It seems like I can't vent the furnace under the porch. I could pipe it out the side (through the lattice), but that leaves it a couple feet below the surface of the deck.

Anyway, what are the code requirements for furnace vents? Distance from ground, windows, porch, etc? My town says:

APPLICABLE CODES: The Town of Bedford is currently operating under the 1996 BOCA BUILDING CODE for non-residential construction and renovations. New construction and remodel/renovations for residential one & two family dwelling units and town houses is governed by the 2000 INTERNATIONAL RESIDENTIAL BUILDING CODE.


mattison
08-25-04, 09:49 AM
You should be able to go down to the local library to read up on the code they are following. Also if you are getting this inspected you could talk to the inspector ahead of time and see how he wants it done.