Horizontal furnace in the foundation crawlspace

[Keith Swift, PhD.]

I inspected a house today that had a horizontal furnace/blower fan, and evaporator coil in the foundation crawlspace with the condensing coil a few feet away behind a garage. The system was manufactured by Ruud, was fairly new, and working well, but here's the rub. I could see the design of this system turning into a lawsuit, quite easily. First of all, moisture had entered the foundation crawlspace, which was confirmed by salt crystal formations on the stem walls and the presence of a float activated sump pump. I could have pointed out that we don't get much rain in California, but I wasn't about to. Supposing we happen to get a lot of rain and mold follows, what then? Also the furnace and its blower fan are just inside the crawlspace at one end of the house and, therefore, are not centrally located. And, as we all know cold air falls, meaning that for opitmum design the furnace/blower fan should have been centrally located in the attic. In short, I expressed my dissatisfaction with the design, pointed out one or two other deficiencies, and recommended a specialist evaluation of a relatively new and functional system, thus possibly avoiding a lawsuit.

[Dale Duffy]

Great idea Keith...you have a picture of the beast? I have never seen one in a crawlspace, but then again I haven't seen may crawlspaces here either.

[Russel Ray]

Originally Posted by kswift

I inspected a house today that had a horizontal furnace/blower fan, and evaporator coil in the foundation crawlspace with the condensing coil a few feet away behind a garage. The system was manufactured by Ruud, was fairly new, and working well, but here's the rub. I could see the design of this system turning into a lawsuit, quite easily. First of all, moisture had entered the foundation crawlspace, which was confirmed by salt crystal formations on the stem walls and the presence of a float activated sump pump. I could have pointed out that we don't get much rain in California, but I wasn't about to. Supposing we happen to get a lot of rain and mold follows, what then? Also the furnace and its blower fan are just inside the crawlspace at one end of the house and, therefore, are not centrally located. And, as we all know cold air falls, meaning that for opitmum design the furnace/blower fan should have been centrally located in the attic. In short, I expressed my dissatisfaction with the design, pointed out one or two other deficiencies, and recommended a specialist evaluation of a relatively new and functional system, thus possibly avoiding a lawsuit.

Hmmmmmmmmm.

I don't know, Keith.

It almost sounds like someone who is totally paranoid about the possibility of a lawsuit.

I find lots of furnaces in foundation crawlspaces here, especially in the 750-SF beach houses with flat roofs (so that everyone has a view) that are built so close that they are almost on top of each other (so that lots more everyones can have a view).

Is there really any difference between what you describe and a furnace that is not centrally located in the attic, which happens to be about 75% of the attic furnaces that I inspect.

What if the roof leaks and no one catches it until lots of mold has grown in the attic and been circulated throughout the house. What if the primary drain (or the secondary drain) get clogged and start leaking into the attic, causing mold to grow and, again, get circulated throughout the house through the heating and cooling system. Same difference?

If the furnace was working and installed properly, I would have simply recommended "regular homeowner monitoring and maintenance," regardless of whether it was located in the foundation crawlspace or attic.

But I am reminded of your story about how report writing has changed. Perhaps you are leading the way to the next generation of report writing:

1 - Kitchen faucet leaks.
2 - Kitchen faucet leaked.
3 - Kitchen faucet leaked and needs to be repaired.
4 - Kitchen faucet leaked and needs to be repaired by a licensed plumber.
5 - Kitchen faucet leaked and needs to be repaired by a licensed plumber before close of escrow.
Keith - Kitchen faucet leaked and needs to be repaired by a licensed plumber before close of escrow. If you move into your new home without having the leak repaired by a licensed plumber before close of escrow, the constant dripping might interfere with your sleep since noises appear to be louder at night since there are not as many noises competing with each other. Lack of sleep might interfere with your job performance, possibly causing you not to get the job promotion and raise that you were expecting to help you pay the outrageous mortgage on your 640-SF dump. The constant dripping might also cause headaches, causing you to have to resort to high-priced medical evaluation and/or prescriptions. The dripping will also waste many gallons of water, thereby increasing your water bill. Without that job promotion and raise, you might be unable to pay your increased water bill, the medical bills, the prescriptions costs, and your mortgage, possibly causing your mortgage lender to foreclose on your 640-SF dump. When that happens, please feel free to contact me for a home inspection on your San Diego River-view property under the I-805 bridge.

[Bruce M. Graham, III]

Crawl space install is common as well as the dead dinosuar syndrom where the old unit is left under the house. Not to worry.

[Russel Ray]

Originally Posted by bgraham

dead dinosuar syndrome

I like that.

I had a dead dinosaur at one of yesterday's inspection. I know why they left it, but I will never understand how they got the new furnace in that crawl space. It was by far the tightest crawl space I've ever gone into. I think that, in addition to not walking on roofs, I shall quit crawling under houses. I'll get Ms Margarita and Dr Cuervo to do it for me, if I can get them away from the beaches.

[Gerry Beaumont]

Originally Posted by rray

Hmmmmmmmmm.

I don't know, Keith.

It almost sounds like someone who is totally paranoid about the possibility of a lawsuit.

Originally Posted by Woody Allen

Just because you are paranoid, it doesn't mean the Ba$T@rds aren't out to get you

Regards

Gerry

[sspradling]

Russell, the same people put those furnaces in the crawlspaces that put those sail boats in the bottles.
Stu

[Russel Ray]

Ah-ha!
Probably the same guy who put $1,000 in that tiny bottle at the mint, too, right?
I've got to make new friends.

[Robert J. OConnor]

Sounds like you are just not used to seeing a combination heat/cool system in a crawl space. The optimum system would be cooling from the attic (yes, cool air falls) and heating from the basement/crawl (hot air rises). But there are many combination heat/cool systems located in either space. It's considered acceptable practice, and works well if layed out correctly (like any other system), but there should be a combination high/low return.

In my mind the moisture penetration and potential mold (where there is moisture there can be mold) is really a separate issue from the mechanical systems as long as it has insulated metal ducts for distribution. However, if it was an open under floor crawl plenum (no tight metal ducts for supply and/or return) I could see that as being a real concern.

[cbottger]

I would have to agree with Robert as an exceptable practice if installed properly but my personal opinion as a past installing contractor I Think it is a straw of last resort and have never personally installed a unit in a crawl space and would have tried to deter the thought.

I have a off beat ethic question but it was concerning the A/C ducts.
I inspected a slab on grade repo in a very exclusive neighborhood with the ducts in the slab. The seller and real estate agent were present and as I was checking the registers for moisture and made the statement to those present that I often made wages for the day by finding dimes and quarters in the registers and I said this as a joke. The seller stated that he would split with me what ever amount that I found. I just laughed and continued on and got to the next register and saw something strange and asked the seller if his offer of splitting with me still stood as there was something in the register back about one foot and he stated sure but if it had hair then I could have it all. I pulled out a pop corn jar and counted out $1001 that appeared to have been there for a long time.

The seller had never lived in this home as he purchased it for a flip.

My question to you guys is who got the money????

[David A. Andersen]

The system was manufactured by Ruud, was fairly new, and working well

So you have NO problem.

I could see the design of this system turning into a lawsuit, quite easily. First of all, moisture had entered the foundation crawlspace, which was confirmed by salt crystal formations on the stem walls and the presence of a float activated sump pump.

Moisture entering the CS is not an HVAC issue.

Also the furnace and its blower fan are just inside the crawlspace at one end of the house and, therefore, are not centrally located.

There are package units installed on the outside of the house at one end of the house. They work just fine.

A point to consider, is that a centrally located unit requires two branch circuits that must proportionally split the air flow. This is much more difficult to calculate and design. A straight run, downsized in accordance with friction loss is the best design if at all possible.

And, as we all know cold air falls, meaning that for optimum design the furnace/blower fan should have been centrally located in the attic.

The natural convection of air should not be a concern for air delivery in a properly designed duct system. Natural convection is a factor after the air is discharged from the duct system.

Blocked air flow from floor registers by furniture is a greater concern.

Placing an A/C unit in the attic has detrimental effects in the efficiency of the HVAC unit due to the excessive temperature extremes found there in summer and winter. It is the last place I would consider placing the unit, but is where it needs to be a lot of the time. Still, not the best choice of location.

[Keith Swift, PhD.]

I've seen tons of such installations, and never really make a fuss. I just make darn sure that I don't completely endorse such a design. Remember, what I said about its return-air grill location, not simply being under the house but at one end of it. The air-conditioning was working nicely in the living room, kitchen, and laundry room, but the volume of air in the bedrooms on the opposite side was weak, and the rooms was decidely warm. Knowing what I know about how inspectors have been victimized, and wishing to serve my clients as best I can, I'm only going to endorse an optimum design. Gentleman, you're all calling it very intelligently and as you see it, and I congratulate you all. Let's keep on sharing, and agreeing to dissagree.

[Keith Swift, PhD.]

P.S.Oops. The return-air grill was not under the house. It was at one end of the house, above the unit, and close to the floor. It was also limited in size, about ten-by-ten-inches.

[Russel Ray]

In the olden days, we built (maybe I built is better) houses with the inflow register on an exterior wall of a room and the return register on an interior wall. We don't do that anymore, preferring to let the bottom of the door serve as the return register. So my question is this, "How many of you check to make sure there is ½" to 1" of clearance at the bottom of the door?" I regularly find that such clearance is minimal or nonexistent after the new carpet people have been in and educate my Clients about what can happen in a home when good circulation is not present.

[Bruce M. Graham, III]

This has to do with duct design, in a perfect world with the right contractor there is more than one return and the duct is completly sealed. Its all in the layout.