Question about outside air for propane furnace

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d.sebens

New Member
Oct 26, 2021
40
White Heath Illinois
My house has a late 90’s 90 plus propane furnace. Nobody ever hooked up the outside combustion air inlet so it just draws from the basement. The house is not tight, the basement is uninsulated and has cheap basement single pane windows. Do you think I should add the fresh air intake? How much would that raise the efficiency do you think? Also can someone find the manual for this furnace? It’s a comfortmaker enviroplus90. Thanks in advance!
 

festerw

Minister of Fire
Nov 16, 2009
532
Cambridge Springs, PA
It won't raise the efficiency much probably but it will help stop pulling more cold air into your home.

There's no good reason to not have the it hooked to outside air if it's able to be.
 

zrock

Minister of Fire
Dec 2, 2017
1,199
bc
no big deal drilling through the brick... Go to your local tool rental company they will have a drill you can rent and have the hole punched in quickly
 

EbS-P

Minister of Fire
Jan 19, 2019
1,713
SE North Carolina
I would not bother. I would Spend time and money air sealing. Once your house is tighter then yeah it’s on the list of items to tackle.
 

d.sebens

New Member
Oct 26, 2021
40
White Heath Illinois
Fair point. I was able to find the manual and they want both intake and exhaust on the same atmospheric plane. My exhaust vent is on the roof and furnace is in the basement. So by their rules I need to run an intake up there so I don’t end up creating a perpetuating flow chimney in the furnace I guess.

I have the old bvent pipe sealed off and unused. I wonder if I piped the combustion air intake into that? It would be really easy to do but both pipes are next to each other and same height at roof exit.
 

Bad LP

Minister of Fire
Nov 28, 2014
1,845
Northern Maine
Fair point. I was able to find the manual and they want both intake and exhaust on the same atmospheric plane. My exhaust vent is on the roof and furnace is in the basement. So by their rules I need to run an intake up there so I don’t end up creating a perpetuating flow chimney in the furnace I guess.

I have the old bvent pipe sealed off and unused. I wonder if I piped the combustion air intake into that? It would be really easy to do but both pipes are next to each other and same height at roof exit.
My LP boiler draws sealed outside air thru the sidewall of the basement and vents thru the chimney some 30 feet up.

Wood boiler does the same thing (same intake but has a powered damper) but it is not sealed combustion.