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-   -   Getting basement air into the return? (http://www.houserepairtalk.com/f8/getting-basement-air-into-return-3340/)

Quattro 01-08-2008 12:12 PM

Getting basement air into the return?
 
Hi all, in addition to fixing that little problem with the condensation in the corner of my basement, I'd like to start thinking about making the space more "conditioned". It's only partially finished, but it is a pretty dry basement most months of the year. Only when it's very humid outside in the summer months does it feel a little damp. No water issues to speak of, no sump.

We use the finished space as our "TV room", so we'd like to condition it at least a little bit. The previous owner simply punched a few gnarly holes in two of the main heat (forced air) runs that feed the main floor (1 story modified ranch). The warm air that trickled out of these holes wasn't making any difference in the basement, so I sealed them back up to feed more warm air to the main floor.

However, I would like to get the air moving in more of a "circular" fashion. There is only one basement access, and it's a narrow stairwell. So I'm thinking of somehow letting the furnace "grab" some of the basement air in two of the main floor return ducts. If I just place a few adjustable vents on these returns in the basement, will that help? I just think I need to somehow get the basement air involved more in the whole-house circulation...and this seems to be an easy way...even though there wouldn't be any warm air re-entering the basement. We're probably going to install some baseboard heaters for that next winter.

Sorry for the disjointed post...it's difficult to explain. Perhaps I'll take a few pics tonight and post them up.

glennjanie 01-08-2008 04:43 PM

Hello Quattro:
The furnace normally would be sitting in the basement in this situation. If that is the case here the return air duct runs down to the bottom side of the frunace and return air vents could be placed in that. I would open a couple of supply holes too. Circulating the air would fight any moisture (which is normal and natural with concrete and masonry ) and the basement won't take that much heat if it is mostly underground.
Glenn

Quattro 01-08-2008 07:35 PM

I was just looking around online, and might try something I saw...grabbing one of the main warm air feeds for the main floor and, just as it turns to go through the floor, make it also go downward along the basement wall and out at the basement floor. This, along with an ample vent in the main return trunk should help, right?

Another thing that will help with keeping the basement warm is to insulate the walls. I did say it was finished, but not with insulation...luckily it's not drywall, only tongue and groove planks. I'm really digging this EPS foam board stuff, and I think I'll use it on all the exterior basement walls in the finished area. A little more expensive, but easy to work with and effective.

Thanks for the info Glenn

Quattro 01-08-2008 07:37 PM

Oh, and I'd put a return hole in the bottom side of the furnace, but that is right next to the floor drain. I don't really want to be introducing any "fumes" that might linger in that area (although I never smell anything funky).

Hube 01-09-2008 07:53 AM

The location of Return air right at the furnace is NOT a good idea(mainly safety).Returns are BEST situated as far away from the furnace area as possible. The same goes for any supply runs. Supplys should terminate at LOW floor level and any returns should also be located at LOW floor level , but as far away as possible from the supply.(supply and returns are best located on opposite walls for the best circulation.)
And INSULATION of the walls in the area to be conditioned is a 'must"
Depending on your locale (climate) you live in would determie the amount of R value of the insulation, but imo it should be no less than R 12.

If you are considering "intercepting" any supply runs from the upper level make sure that you install dampers at the take-off point so you can shut them off when not required.
If you have any more questions on this feel free to ask.
good luck. Hube

Quattro 01-09-2008 07:59 AM

Ah! Great point about the dampers...because I don't need to cool the basement air in the summer, or heat it when we're away.

I will focus on the insulation first, then the venting. Thanks!

glennjanie 01-09-2008 02:15 PM

Hey Quattro:
Your plan sounds good to me and the floor drain will not be a problem as long as the water in the trap doesn't evaporate out. We like to use an automatic trap primer in these cases but you can add a quart of water once a month and as long as the water reflects a full circle in the bottom you will be sealed.
I like your supply lines running down to the floor but it is not necessary in a basement. If it is mostly underground it is far easier to heat and cool.
Your supplies at the perimeter wall and the return being at the furnace, which is normally in the center of the house, should give you sufficient circulation of the air.
Glenn

Hube 01-10-2008 07:08 AM

Quote:

Originally Posted by glennjanie (Post 14070)
Hey Quattro:
Your plan sounds good to me and the floor drain will not be a problem as long as the water in the trap doesn't evaporate out. We like to use an automatic trap primer in these cases but you can add a quart of water once a month and as long as the water reflects a full circle in the bottom you will be sealed.
I like your supply lines running down to the floor but it is not necessary in a basement. If it is mostly underground it is far easier to heat and cool.
Your supplies at the perimeter wall and the return being at the furnace, which is normally in the center of the house, should give you sufficient circulation of the air.
Glenn

__________________________________________________ ______________

Quattro. The above advice is simply not the ideal methods.
First of all, it is best NOT to have any return air intake grille situated right at the furnace because it could "create a "negative" pressure and this can "draw" unwanted fuel fumes,flame,odor etc, in that immediate area.
Also,what happens if you 'forget' to add water to this floor trap.??? This sewer gas and odor would be sure to be 'sucked' right into the furnace duct system, whereas if the return was situated further away this would not be a problem.
A basement is no different than any other level in your home. Sure,the heat loss/gain is different because of the ground protection, but hot air (in the heat mode) still rises, so why not start the air to enter the room LOW where you are sitting or laying.
And it is also not uncommon to have a furnace installed elsewhere in the basement other than in the center.
Btw; I have 50 years experience in Hvac(now retired)

Quattro 01-10-2008 07:51 AM

Thanks to you both. It's always interesting to hear two opinions that don't exactly match. I appreciate them both! My father in law is also an HVAC professional who now teaches at a Technical College in that field. I've asked him about this before, but never when he was around to actually look at the situation.

The furnace isn't exactly in the center of the house, rather it's offset from the center about 10 feet. The return is also right next to the gas water heater...which seems to emit a fume or two when it ignites. Since the basement ceiling is unfinished, it really wouldn't be trouble to make a drop from one of the main returns down to the basement floor level...and the same with a supply run.

I think once I get the finished area insulated (most of it is below-grade, except for the 1 foot at the top of the foundation that is above-grade), adding a supply and return in the above method should help greatly.

Thanks for your help!


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