You don't want basement air upstairs (article post)

There have been a number of discussions regarding recirculating cooler basement air during the AC season. The following is an article (stolen without permission) from http://ludwig-associates.com /. Jerry Ludwig runs a Home Inspection business in western New York and answers homeowner's questions in a weekly newspaper column.
I'm guessing this may start another lively discussion...
Headline: You Don't Want Basement Air Upstairs Democrat and Chronicle Column # 27-07 July 7, 2007
Dear Jerry: I have always wondered if there is a way to circulate the cool, basement air to the upper two floors of the house during the warm summer months. I have a standard air conditioning system blown by my forced air furnace. I have pretty good success at cooling the first and second floors of the house, but every time I go into the basement, I am amazed at how cool it is and I wonder how I can get some of that air upstairs.
I do not have any of the dampers open in the basement and there are no cold air returns directly into the furnace in the basement. Is there a system that can blow the cool air into the furnace? Is it worthwhile to put one or more cold air vents into the system in the basement? Any advice would be helpful and may save me some money. M. C., via email
There are two basic reasons why your HVAC system does not have basement returns. One, in our climate, the systems are designed primarily for heating. This is normally true whether or not one adds central cooling. Thus, circulating air on the first and second floors is the primary focus of the system's design.
However, the second and most important reason why there are not cold air returns in the basement is one of safety. Because most heating systems rely on natural fuels to provide heat, keeping returns away from potential hazards in the basement is an important design criteria.
If there was a malfunction in the furnace's fuel delivery system (gas leak, oil leak, etc.) fumes from the basement could easily be spread throughout the house creating a potentially dangerous situation. And, should a fire develop in the basement, an open return could spread the fire and/or smoke rapidly throughout the house.
In addition, since the laundry, wood shop, and other places that may be home to potential combustibles and chemicals such as bleach, paints, sawdust, etc., are often located in the basement, keeping these areas separate from the furnace and air conditioning systems is a very good idea.
Finally, the basement can be damp and musty, even on a good day. Spreading this tainted air around the house can create indoor moisture and odor issues during winter months.
Supply registers are often used to supply the basement with warm circulating air during winter months and I usually recommend that the warm air registers be kept open during the winter months. Finished basement rooms are often supplied with warm air registers, although often some type of auxiliary heat may be necessary to keep the rooms at a comfortable temperature.
My advice is to allow the basement to remain cool during the summer while using the air conditioning system as necessary to keep the main floors comfortable.
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He makes a number of assumptions that may or may not be true. In northern climates, the basement is normally heated and requires an air return for this purpose. If the basement is made into a liveable area, you will need returns to ensure that the heat is distributed.
Many of his assumptions could cause some people who do not know much about the operation of their house and climate to be afraid of the basement air, with the variables in construction styles, age of building and many, many other conditions, the advise really only applies to a limited number of homes and the rest he doesn't cover -- as it would require a whole book.

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Would you have any evidence for this article of faith? :-)
Nick
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NREL says the average deep ground temp in Pittsburgh is 50.3 F. A 2400 ft^2 basement floor with a 2 Btu/h-F-ft^2 airfilm resistance could contribute (75-50.3)2400x2 = 118.6K Btu/h (10 tons) of cooling to a 75 F house before it warms up. The ASHRAE HOF gives 8 Btu-in/h-F-ft^2 as a conservative soil conductance for earth cooling.
Nick
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On Mon, 9 Jul 2007 18:17:18 -0400, "Charles"

No that's not true, it is evidence. One example is not the best evidence, compared to two or ten examples, but it's still evidence. In addtion, you lived there and had the opportunity to pay close attention. OT3H, you probably didn't do actual measurements.
Lately, on tv, the script sometimes implies the only evidence is printed evidence, or sound or video recordings. That's not true. One person's testimony of what he saw or heard is still evidence.
And OTOH for the last 60 or more years, we've heard the caustic remark, "That's just circumstantial evidence", as if that means it's no good. In fact, most criminal convictions in the US and elsewhere are based entirely on circumstantial evidence. Which is everything but eyewitness testimony of someone who saw the crime committed. Paperwork, autopsies, blood evidence, all crime scene evidence, all lab work, ballistics tests, everything that a witness didnt' see or hear is circumstantial.
If you see someone A walk into a room carrying a gun, hear a bang, and you walk in to find B on the floor, and A holding a smoking gun, that is all circumstantial evidence. Does that mean it's not good in our system? (IIUC, in death penalty cases in Israelite and Jewish cases under Biblical law, circumstantial evidence is not admissable, but that's not the law we use. Although maybe that is where people got the idea it is never any good.)

I live in a tiny valley next to a small stream. The hills around me within 200 yards are probably no more than 20 ft. high, and no more than 40 feet within 400 yards. But I've started to think this is why I have so little breeze. I love my little stream which turns 90 degrees just a few feet past my house, and the little bit of woods around it, and was amazed to find it next to a townhouse. I've still never see a better lot in this town, even for a full size house.
But I rarely have a breeze.

Thought I would need it today. It was 98 but only 26% humidity in Baltimore and not so bad.

I did test for that 20 years ago and I passed. Do I have to test again?
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wrote:
I have two answers for this, one on topic and one somewhat off topic, that should follow within 12 hours.

Despite his first sentence, and that this is a common way of thinking, this is not a reason why it doesn't have them. What he says is that even though houses have heating and air conditioning, heating is the primary goal in laying out the ducts, so they didn't consider air connditioning. That's not a reason, that's a failure. Or it's a reason why the failure is not so bad. But it's not a *reason* they don't include those ducts.

The ONLY cold air return is my house is in my basement. The basement has two rooms and the return is on the other side of the wall from the furnace, and the door is 3/4 of the way along the wall from the furnace, so it's almost as far as it can be, but it's still in the basement.

I guess I'm at risk.

Maybe a basement can be, but my basement is almost never damp or musty, even on a humid day. Even the day after the drain has backed up. Let alone a normal day.

24 years, and I've only had an odor for 6 weeks at the end of last winter, and only from one vent. For this I should give up 24 years of cooling?

Even with a warm air register? Basements don't get as warm in the summer or as cold in the winter.

Will he pay for it?
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You can't smell CO!!!!!
But it can/will KILL you!!!!!!
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wrote:

And you can buy a CO detector at Home Depot for thirty bucks.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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That WON'T protect you from low level CO poisoning!!!!!!
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Why would you say that?
Nick
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wrote:

What makes you think that?
For that matter, what makes you think that CO levels too low to trigger a detector constitute "poisoning"? You seem to think that any level at all, no matter how low, is a deadly poison. Maybe you ought to take a CO meter with you in the car as you commute to work, and see how much CO you're breathing from other vehicle's exhaust fumes.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Strange that all his objections, with the possible exemption of the moisture, apply equally to a house with no basement. What does he recommend to be done with the HVAC and laundry systems in those type houses I wonder.
Harry K
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wrote:

I was wrong about this. There is an air return 2 1/2 floors directly above the one near the basement floor. (for heating and cooling, if in practice it works that way.) Both grills are in the stairwell, one near the ceiling on the second floor and the other near the floor in the triangular space below the top half of the basement stairs.

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Not an HVAC specialist but that sounds wierd to me. Just 'shade- treeing' it I would think only the bottom one would be effective (coolest air and nearest the furnace) as it would be the easiest air to move.
Harry K
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wrote:

Yes, it seems that way to me too, and in my last poast I was going to start in on theorizing like you're doing when I remembered that when I removed the grill for painting a few years ago, it was dirty.
So I just got up now and the new one, which is taller than it is wide and goes from about 5'6" to just short of the 8 foot ceiling, is dirty too, and almost the same amount of dirty everywhere. Even nearest the ceiling was about as dirty as 2 feet below that.
It is obviously being used during the heating season, and for all I know during AC use too.

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One word: Radon.
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Oh, please. Radon isn't anywhere nearly the health hazard that it's made out to be. And in a basement with a poured concrete floor, it's basically a non-issue.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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I think a better answer for the intelligent DIYer is to weigh your situation and act upon it.
We cooled using basement air for a dozen years. I turned the furnace pilot off for the summer and just opened the bottom of the furnace. We didn't have lint in the basement, so that wasn't a problem either. A little hokey, but it worked. I closed up the bottom of the furnace during heating season, of course! Just don't do anything stupid.
And I agree that once you've sucked the cool air out of the basement, it becomes almost as warm as the rest of the house, except that the ground keeps on cooling the basement to some extent.
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