Portable Air Conditioner - One hose or two?

[Bob Borzelleri]

We apparently just missed setting a record for triple digit days that goes all the way back to just before the establishment of the first California mission. Despite failing to hit the mark, I decided that it was time to consider options for reducing the blast furnace effect in the shop for those times when I want to work prior to 10 PM.

Off I went to buy a portable air conditioner. That was a real experience. As I walked into Lowes, I was met by several people with flat bed carts with stacks of room air conditioners heading out the door. I can only guess that these folks had decided that super hot days in the Sacramento Valley translates to "business opportunity". In fact, Lowes had just run out of all but the smallest room A/Cs.

Well, rather than troll back alleys looking for vans with the doors open, I decided to let my fingers do the walking (we live about 45 miles up the road from Sacramento and the nearest big box store is still something of a drive).

To make a tiring story somewhat bearable, virtually everybody was out of what I had suddenly decided I wanted; a portable A/C. My last call was to Best Buy whose web site had shown zippo units in stock, but I thought I'd give it a chance. The first guy I spoke to laughed a lot reminding me of the highest number of consecutive XXX days since before the gold rush record, (the actual date of the record seems to be a moving target), but he transferred me to a very nice young woman who said, "well, since you need one today and we are out of stock for the rest of the week, I can (quietly) tell you that Staples has them".

Off to Staples I went only to watch the last Haier 12K BTU unit getting loaded up. Not to worry said the Staples person, "we have seven coming in tomorrow", so I put my name on the list and today brought the box home and hooked it up and turned it on.

All of which leads up to the rather perplexing situation I find myself pondering and which is the topic of this note; Haier touts a design that has one hose for outside exhaust and one hose for outside intake. Outside air often being hotter than the air in the room I am trying to cool leads me to question the physics of this design.

It seems to me that auto manufacturers have been providing inside circulation buttons to shut down outside air intake for maximun cooling. Then again, perhaps the air they are wanting to shut down is significantly higher in temperature than general ambient air because it is drawn from close to the engine.

So, what do you think? It doesn't sound intuitively sound to me, and the Haier customer service person told me she found herself having to take the explanation that was given to her by the tech folks on faith (they apparently get a lot of calls on this one).

...Bob

[Don Baer]

The house airconditioner uses the cold air return so it recircs the air.

[Bob Borzelleri]

OK, here comes the thread killer.

The intake hose draws air in to run over and cool the compressor and then it is routed into the exhaust channel hose. The air that comes into the system from the outside duct never becomes a part of the cooling process for in-room air. It simply gets invited in to cool off the compressor (presumes that the compressor is always going to be hotter than outside ambient air, I suppose) and then gets thrown out like worn out underwear.

Amazing thing that Google.

...Bob

[Ken Garlock]

Don't worry Bob. :)

The two hoses supply and exhaust the air used to cool the compressor and condensor unit. Your inside air is sucked in at the front grill, or somewhere near, and then after cooling blown out into the room. Your room air is not in contact with the air flowing in the two hoses. Yes, you need both hoses attached to the unit, and terminated outside the area you are cooling. Try to keep them as far apart as you can, no sense in one hose sucking in the hot air exhausted by the other hose, and thus putting an undue load on the system. :(

[Bob Borzelleri]

Don't worry Bob. :)

The two hoses supply and exhaust the air used to cool the compressor and condensor unit. Your inside air is sucked in at the front grill, or somewhere near, and then after cooling blown out into the room. Your room air is not in contact with the air flowing in the two hoses. Yes, you need both hoses attached to the unit, and terminated outside the area you are cooling. Try to keep them as far apart as you can, no sense in one hose sucking in the hot air exhausted by the other hose, and thus putting an undue load on the system. :(

Thanks Ken...

It's interesting that you mentioned keeping the hoses as far apart as I can. THe manual says the same thing, but the window kit has holes that are about two inches apart. I immediately trashed the kit frame and made my own and put the hoses about 1 foot apart. Note the before and after pics.

As it turns out, this thing really cools up a storm. It also has a heating element (which I wasn't looking for, but I will gladly accept). Since I have nearly 5 feet of crawl (stoop) space toward the rear of the shop, I have been entertaining the notion of running the hoses through the floor. Any thoughts on that idea?Thanks again for the input.

...Bob

[Kirk (KC) Constable]

How's that thing work? I put heater in the shop several years ago so I could get glue to cure in the 'winter'...but have resisted the temptation to give the electric company more $$ simply for comfort in the summer. But the older I get, the more I notice the heat...so it may be time.

Why did you want a 'portable instead of just a window unit?

KC

[Lee DeRaud]

It's interesting that you mentioned keeping the hoses as far apart as I can. The manual says the same thing, but the window kit has holes that are about two inches apart.Any reason you couldn't just put a sheet-metal baffle on the outside to direct the exhaust air away from the intake?

[Lee DeRaud]

Why did you want a 'portable instead of just a window unit?Well, in my case, because the garage doesn't have a window?:p

I've thought about putting one in, but the only chunk of wall I don't already have cabinets on is where the wood gets stacked up. This thing could vent out down low on the wall...assuming I can find a place to plug it in without overloading something.:eek: :mad:

[Bill Arnold]

Well, in my case, because the garage doesn't have a window?:p ...Lee,
Why does it look like your I/O lines are mounted in a window?

:confused:

[Russ Filtz]

The principle is no differrent than a whole house AC. The compressor sets outside and the compressor cooling air (actually it's condensor cooling air, but I'm sure the compressor and motor get some benefit) gets sucked in and blown back out, outside. You didn't think the air going through a whole house AC compressor came through the little pipe into the house did you? ;)

[Ken Garlock]

Hi Bob. I would think that putting some 6" PVC pipe under the floor would work OK. But, I would not run it too far or you will begin to get pressure drop in the pipe both coming and going due to air friction in the pipe. You don't want the system to think it is sucking air through a soda straw while trying to blow up a balloon ;) Don't ask what too far is :confused: I suggest 6" to help reduce the pressure drop due to friction. You could run your hose down thru a hole(in the floor?) and connect it to a 6" by X" reducer to match your hose. That would also give you a chance to run your pipes in two different directions. Lastly, get a couple stainless steel kitchen strainers. Remove screen from the handle, etc., and put screen over the ends of the pipe using a hose clamp. This will keep the local vermin and other 6 or 8 legged creatures out of the system. :eek:

Good Luck. Remember, my advice is worth what you paid :) :)

[Lee DeRaud]

Lee,
Why does it look like your I/O lines are mounted in a window?

:confused:Because that's not my garage, it's Bob's.

[Bob Borzelleri]

How's that thing work? I put heater in the shop several years ago so I could get glue to cure in the 'winter'...but have resisted the temptation to give the electric company more $$ simply for comfort in the summer. But the older I get, the more I notice the heat...so it may be time.

Why did you want a 'portable instead of just a window unit?

KC

KC...

Security was probably the deciding factor. With this arrangement, I can easily take the window kit out and the window closes up as secure as it was before. With the window A/C always in place, there is always the chance that a crime of opportunity will occur simply because most people view window units as pretty easy to remove from the outside.

As for how it works, it's currently 99 degrees outside and I've had the A/C running for 3 hours. The shop started out at 90 degrees before the A/C came on. It is now 84 in there. Given that the pattern has been for the closed building to reach several degrees higher than the outside temp, and that the A/C has been working for only 3 hours (building is 524 sf), I am satisfied. I would think that adding some mini blinds or window film would help greatly.

A 12K BTU machine is usually rated for 450 sf, although some of the manufacturers assert 650, so at 524 sf, I think this will work out fine.

...Bob

[Bob Borzelleri]

Because that's not my garage, it's Bob's.

Yup. It's my shop. And them's my i/o lines.:)

...Bob

[Bob Borzelleri]

Any reason you couldn't just put a sheet-metal baffle on the outside to direct the exhaust air away from the intake?

I thought about that. Then I got to thinking that I had this left over bead board and a fresh scroll saw blade...:rolleyes: :rolleyes:

...Bob

[Bob Borzelleri]

Hi Bob. I would think that putting some 6" PVC pipe under the floor would work OK. But, I would not run it too far or you will begin to get pressure drop in the pipe both coming and going due to air friction in the pipe. You don't want the system to think it is sucking air through a soda straw while trying to blow up a balloon ;) Don't ask what too far is :confused: I suggest 6" to help reduce the pressure drop due to friction. You could run your hose down thru a hole(in the floor?) and connect it to a 6" by X" reducer to match your hose. That would also give you a chance to run your pipes in two different directions. Lastly, get a couple stainless steel kitchen strainers. Remove screen from the handle, etc., and put screen over the ends of the pipe using a hose clamp. This will keep the local vermin and other 6 or 8 legged creatures out of the system. :eek:

Good Luck. Remember, my advice is worth what you paid :) :)

Thanks Ken...

I'll probably think about the floor routing after I get around to rerouting the dust collecting duckwork under the floor. Since that won't happen until after I get the ceiling ductwork mounted and used for awhile, my guess is that the A/C through floor project is off into the future. The idea about a varmint screen is a good one. Thanks again.

...Bob

[Bill Arnold]

Because that's not my garage, it's Bob's.
:o

Well.....duhhhhhh on my part. No wonder LOML questions my 'powers of observation' at times...:confused: :eek:

:D

[Mike Kelly]

Bob, that's a nice looking unit. You might want to start thinking about a filter system for it. The coils will get plugged with sawdust pretty quick if you don't.

I used a clean room filter adapted to a frame I molded to the face of the air return. Even with this huge filter the reduction in airflow is noticable. The filter extends almost to the floor below the bench. Not a good picture of it, but the only one I could find quickly. Stay cool.

[Michael Perata]

We apparently just missed setting a record for triple digit days that goes all the way back to just before the establishment of the first California mission. ...Bob
I can tell you Bob is not exaggerating about the heat. I was stuck in an accident slowdown at the junction of Interstate 80 & Cal Hwy 65 (about 28 miles away) yesterday at 5:30 PM and it was 108...and then my air conditioner broke. :mad:

[Lee DeRaud]

I can tell you Bob is not exaggerating about the heat. I was stuck in an accident slowdown at the junction of Interstate 80 & Cal Hwy 65 (about 28 miles away) yesterday at 5:30 PM and it was 108...and then my air conditioner broke. :mad:I was in Texas last weekend...I think the Heat Monster followed me back.:eek:

In the words of Maxwell Smart, "Sorry about that, chief.":cool:

[Bob Borzelleri]

Bob, that's a nice looking unit. You might want to start thinking about a filter system for it. The coils will get plugged with sawdust pretty quick if you don't.

I used a clean room filter adapted to a frame I molded to the face of the air return. Even with this huge filter the reduction in airflow is noticable. The filter extends almost to the floor below the bench. Not a good picture of it, but the only one I could find quickly. Stay cool.

Thanks for the tip, Mike. One of the questions I had when I opened the box was how well the return air filter would work. It turns out to be pretty sparse in it's filtering capability. I'm sure it will clog quickly. I like the idea of the filter box.

...Bob

[Bob Borzelleri]

I can tell you Bob is not exaggerating about the heat. I was stuck in an accident slowdown at the junction of Interstate 80 & Cal Hwy 65 (about 28 miles away) yesterday at 5:30 PM and it was 108...and then my air conditioner broke. :mad:

I can relate to the infamous I-80/CA-65 junction. Before I retired, I had an office in Sacramento and had to drive past the intersection on my way home 1/2 way between Sacramento and Lake Tahoe.

It could be 95 degrees when I left my office and 16 miles later (at the junction in the city of Roseville), it could get to 110-115. By the time I got home, the temp would be between 82-85.

My theory is that the city of Roseville, which is considered one of the fastest growing development areas in the country, is affected by a combination of crystals and vortexes. In addition, I think the city was built on a very old burial ground for the aliens who established the underground network of tripod war machines that Tom Cruise tried to stay one step ahead of. I read somewhere that the effort of digging all those holes was simply too much for them so they were buried where they fell. It apparently takes thousands of years for their bodies to decompose and the latter stages can create significant heat.

Michael's air conditioner likely fell victim to the crystal/vortex thing.

...Bob