Not using outside air for basement only HVAC?

9 years ago

My parents just closed on their new construction home. They had it built with a full basement for which my dad felt some compulsion to have heated. I am not sure if he has a/c down there or not, we tried to tell him not too, that a dehumidifier would be fine in the summer. It's a big basement and I noticed at least 5 supply vents, maybe more.

Anyway, I went over for the walk-thru and noticed the 2 pvc pipes for intake and exhaust, one is vented up and out (somewhere) the other is just a little curved pipe about 8 inches long. I assume that one is the intake. This system is solely for the basement. Does that make it ok to not use outside air? The attic unit does have 2 pipes that I assume go out the ceiling. I was worried they had done the same thing up there and I knew that it would not be good to have insulation etc pulled in to the heater.

I don't know if this is acceptable or not. If not, please send me wording or documentation that they can present to the builder to get it changed. My dad is fine with it.

I'm adding this ....I just realized I didn't see a return trunk line. I assume there is a return vent, maybe right at the furnace? But there was only one big rectangle duct across the basement which I know has supply vents either in it or off of it. That is fine now, but won't they need returns if they were ever to build rooms down there (highly unlikely)? I know they paid an arm and a leg as this was a very unusual thing for the builder to do, they are probably the only ones who asked for it (few homes even have basements in the development). We all know how inflated upgrade prices are, but my dad was bound and determined to have it. The basement is probably about 1600 sf (it's mainly a single story home and the basement is the whole LxW of the house). The main trunk runs across the short width of the house. House is 35 ft wide. How much $$ did the builder/hvac installer save by not putting a return duct? (Gloucester County NJ) Should they ask for it to be added? I think (not sure but will ask) they paid about $5k for the furnace, it's very small looking but I don't know the size (yet). It is Carrier.

But hey, they did use that mastic stuff on the seams.

Let me know what to look for when I go over there on Friday.

Thanks and Happy New Year!

This post was edited by cindywhitall on Wed, Dec 31, 14 at 23:50

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Comments (4)

klem1
9 years ago
"Let me know what to look for when I go over there on Friday"

NOTHING,unless you are trained in hvac. Let the folks injoy their new home. Something tells me dad knows what he's doing and you disagree with him spending money on a new home. If you believe their health or life is at risk,take 10 pounds of T-bones by the nearest fire station and request they drop by to check it out.
cindywhitall
Original Author
9 years ago
I could care less about them spending $, they have plenty of it. (they paid for this house and haven't even listed their current one yet!) I just don't like to see shortcuts taken if they were charged for doing it the "right" way. I just want to know if this is an acceptable practice. Dad focuses on strange details and ignores others.

They paid for diagonal backsplash but it was put in horizontal, luckily we caught it and a solution was determined. I just want them to get what they paid for, and since they have never shopped hvac they have less clue than I do.
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mike_home
9 years ago
Cindy,

Below is a paragraph from page 10 for the installation manual for the Carrier 59MN7 modulating furnace. I think you will find something similar for other furnace brands.

"When the furnace is installed as a direct vent (2-pipe) furnace, no
special provisions for air for combustion are required. However,
other gas appliances installed in the space with the furnace may
require outside air for combustion. Follow the guidelines below to
insure that other gas appliances have sufficient air for combustion."

All furnaces need combustion air to work properly. New homes are built very tightly so it is important to have enough oxygen so the fuel burns completely. If the furnace and other gas appliances are operating at the same time it could cause a dangerous situation.

If it were my house I would want the PVC air intake to be installed so it has access to outside air. In my opinion this is an improper installation caused by laziness by the installer. It may be fine, but why take a chance with your parent's home? As you stated they paid a lot of money for this furnace and basement. There is no reason it should not have been done properly.

Here is a link that might be useful: Carrier furnace installation manual
cindywhitall
Original Author
9 years ago
Thanks Mike.

I looked at the manual you referenced and sInce there is only one pipe leaving the basement I assume they did it the second way...I think that is what you are saying. I think they took a shortcut, and since this is a brand new, pretty tight house, I do not think the basement will "freely communicate with the
outdoor to provide sufficient air for combustion", unless it is drawing air down from the main living area, which is not a good plan (imo). I will send the info to my parents and my brother (he had decent understanding of home building--does a lot with Habitat for Humanity but is not a contractor of any type, just a handy guy). My dad is all about safety with smoke and CO detectors everywhere, I don't think he'd like it if it's not done properly and he knew about it.

1. Direct Vent (2--pipe) Applications
When the furnace is installed as a direct vent (2-pipe) furnace, no
special provisions for air for combustion are required.

2. Ventilated Combustion Air Applications
When the furnace is installed using the ventilated combustion air
option, the attic or crawlspace must freely communicate with the
outdoor to provide sufficient air for combustion.