Venting portable A/C into crawlspace?

[CarvedTones]

I have a two car garage with an inside and an outside wall on the sides. My wife's car is parked on the outside wall side and most of my shop space is on the inside. I have tried to talk my wife into a "trade" but for various reasons (some of which I have to admit are practical) that isn't going to happen; the outside space fits a big van better.

Anyway, I have a portable A/C that uses a single dryer duct exhaust (I know; duals are more efficient, but it works pretty well). I vent it to the outside wall, which is fine when the garage stays closed for long periods, or it isn't very hot or I have backed my wife's car out and am working over in that half as I can direct the A/C right towards me. But sometimes I go out there in the afternoon and the A/C has been off all day and it is hot in the iniside bay. What I would like to do is roll the A/C (it's on wheels) over to the inside bay. I could just run a long extension duct, but for safety I would not want it on the floor and running it overhead would make it really long.

Another option would be to install a second vent on the inside wall because the garage is a few inches below the house floors - there is a 2x8 at the base of the well that is actually below the floor and a hole through it enters the crawlspace.

Would it be a bad idea to vent into the crawlspace? It is hot air, not anything noxious. If I did it, would I need to use something to make sure I did not weaken the structure with a big hole through the board into the crawlspace?

 

[Mr. Bill]

Just curious but is the outgoing air very moist? I used to work in a small office in a wharehouse that used a rolling portable AC and had a "bucket" we had to empty frequently. If this is the case you would be putting the moisture into the crawlspace.

 

[decibel]

Just curious but is the outgoing air very moist? I used to work in a small office in a wharehouse that used a rolling portable AC and had a "bucket" we had to empty frequently. If this is the case you would be putting the moisture into the crawlspace.

Andy I'd agree with bill here if you have a portable that dumps moisture out it's exhaust duct like mine to help eliminate having to empty the water pan constantly. Also consider any condensation just from the hot air I'm starting to see condensation inside my exhaust duct now that I've insulated my shop and got the temps down. I can hear water running through it. Exhaust temps on my unit have been as high as 119 degrees so not sure if that could cause you some moisture problems.

 

[CarvedTones]

Yeah, that is what I have. It has a pan, but it evaporates it. I am warming to the idea of the duct extension just because of the lack of unknowns. It would be long enough that I should probably use insulated ducting, which makes it even bulkier; that is about the only downside.

 

[Mike Davis]

Why not put a small duct gate in the garage door?

 

[CarvedTones]

Mike,

That's way too practical to be acceptable in Cary. My garage doors face the street. Also, I mostly work in the half bay away from the door so it isn't much closer than the outside wall. But you did make me think about one thing - my "loyalty" to the existing vent down low at the back of the garage is rediculous. If I put one up high near my I beam in the middle of the garage, it would be a short run to a spot between the 2 garage door frames where I could easily mount a connector. Hmmm...

 

[Joe Scharle]

Don't dump the moisture into the crawl space. People spend thousands to keep their crawl space dry. Wet crawl spaces invite mold, rot and bugs. I looked at a house in Cary that the dryer vent hose had ruptured who knows for how long and I could push a screwdriver clear through a joist.

 

[CarvedTones]

Don't dump the moisture into the crawl space. People spend thousands to keep their crawl space dry. Wet crawl spaces invite mold, rot and bugs. I looked at a house in Cary that the dryer vent hose had ruptured who knows for how long and I could push a screwdriver clear through a joist.

That's bad, right? :rotflm:

I love this place - good advice quick. I will go overhead and back to the outside wall.

 

[Dudelive]

I would think that you would need the shortest length of exhaust hose possible. Be sure to read the manual that came with the unit as it will more than likely tell about the better places to run the hose.
As in dust collection, I would think short, straight, and as large as the fan will allow to move all the air out as soon as possible.... Just my thinking.

Never exhaust under the crawl area for any reason. Exhaust to the outside maybe using a dryer vent, that way it would not look any different than a dryer exiting the wall, one on each side as needed when moved.

 

[steviegwood]

You could always raise the unit up and vent it through the roof. That way the cold air falls around you and you can make the exhaust a lot shorter run making the unit more efficient. A small roof vent is very affordable. Or it could be piped with pvc. If you make a very long run for the exhaust I would suggest getting an inline booster fan to help export the exhaust which in turn would be adding life to your portable unit. Just my two cents. Steve

 

[CarvedTones]

It is under an upstairs bonus room. I am beginning to suspect I am fighting a battle with the wrong appliance anyway. I think my upright freezer might be the real culprit. It was like a sauna in my garage first thing this morning and the freezer is the source. It is staying cold inside, but apparantly being very innefficient about achieving that. A few months ago I was a lot happier with my A/C; it cooled the whole garage and it was fine for it to be off in a corner. It seems to still be cooling fine when I am right next to it.

 

[Steve W]

Joe's right: don't push warm, moist air into the crawlspace. In fact, crawlspaces should be sealed from outside at least during the summer. DAMHIKT. It cost me over $8k to fix my sick crawlspace but since then, the conditions inside the house are much better!

In addition, I'm sure that there would be some sort of major code violation with moving garage air under the living space due to the possiblilty of CO from car exhaust working its way into the living space - even if you aren't using the garage for cars, it is still nominally a space where internal combustion engines could be in operation.

 

[CarvedTones]

I did not and will not vent into the crawlspace. The responses convinced me that was a bad idea. The real fix is a better seal on the freezer door, as odd as that sounds. It was leaking cold air out and warm moist air in which frosted over the shelves (it's one of the units with cooling coils inside the shelves) which made it even less efficient. The cool air escaping through the door did not come close to offsetting the heat it was giving off trying to keep the inside cold. It finally occurred to me that we had plenty of hot weather after I bought it last year and earlier this year that it dealt with just fine, cooling the whole garage acceptably from the corner and the air was still cold coming out of it - something else had changed the equation. Kinda weird to find out it was my freezer making the garage hot.