Room Air Conditioners

[Charles Bishop]

I've been looking ar room air cons and have a question, or two.

There are two types that I've looked at-window units, and in-wall units. The window units fit into a window, with "ears" at the sides to fill in any empty space. The in-wall units are fitted into a space in a wall, and usually have a sleeve that they slide into. The sleeve is mounted through the wall, supported on the outside and the unit slides in.

Both types are available in 8K and 10K units and with 110V power.

Why does the in-wall unit cost ~$150-$200 more than the window unit for the same specifications?

Would there be a downside to using a window unit as an in-wall unit by framing my own sleeve and making trim for the outside and inside of walls of the room?

Or, do I need a sleeve at all? After all, when the window unit is in a window, the exterior of the unit is exposed to the elements as much as it would be when it is installed as an in-wall unit?

Is it worth it for energy savings to look into getting a 240V unit even though I only need 8 or 10K?

charles

[krw]

Usually not. Window units often have vents in the sides, too close to the front to frame through a wall (thicker than a window).

Split units are ideal for this application.

A converted coal furnace. 60% is horrible. Even old 60s junk was ~80%.

*FAR* more costly for a retrofit.

[Ed Pawlowski]

The in wall unit has a slide in chassis. That makes for easier service and installation. It also costs more to build. I used to supply parts to a major AC manufacturer. They build 4000 to 8000 window shakers a day while the thru-wall units were a specialty small run.

I've seen it done.

Ease of use and ease of installation is the big factor. If you are inclined to build a sleeve, it can work just as well. The heat won't car how it is removed.

No. The cost of putting in a 240 line is more than the potential savings.

[Ed Pawlowski]

That does not work for everyone though. If you have to install ducts for AC, it can get costly in many homes. I'd like central, but since I heat with hot water baseboard, the cost is difficult to justify.

If I had hot air heat, yes, central would be the way to go.

[Stormin Mormon]

The window units draw outdoor air in the sides, and push the heat out the back. If you make a sleeve, you need a LOT of space on the sides, to allow outdoor air to circulate through the condensor.

There is no energy savings to 220 volts. You pay for watts, and it takes some number of watts to move the heat.

What saves money is to keep the AC clean, and to buy one with a rotary compressor, instead of a recip.

Christopher A. Young Learn more about Jesus

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Would there be a downside to using a window unit as an in-wall unit by framing my own sleeve and making trim for the outside and inside of walls of the room?

Is it worth it for energy savings to look into getting a 240V unit even though I only need 8 or 10K?

charles

[George]

If efficiency is a goal you would want to look at mini split units. As a bonus they are much less noisier than the typical window shakers and the only wall penetration is for the refrigerant lines, drain and a control wiring.

[HeyBub]

I disagree.

Consider a typical usage pattern:

A. 6:00 am - 7:30 am | Usually no need for a/c. B. 7:30 am - 6:00 pm | a/c off while everybody's at work C. 6:00 pm -11:00 pm | a/c on D. 11:00 pm - 6:00 am | Need for a/c while sleeping

If you use only central air, it will be on 12 hours a day (C + D). If you have a window unit in the bedroom, the central air will be running only five hours a day (C) and the window unit running seven (D).

The cost difference is between the central air and the window unit for seven hours a day. Even if the window unit is not particularily efficient, it will still cost less than cooling the whole house for those seven hours.

There are obvious exceptions: For example, four bedrooms each with its own window unit may be more expensive than the central unit. But the main point remains: why cool the whole house when only part is occupied?

[trader4]

It depends where you live. My central AC rarely runs after 11PM. I'm in the nyc area and typical night temps are not that high. So, if I want most of the house cooled off in the evening, then the whole house is cooled down and it's costing very little if it comes on some nights a few times to maintain that.

Now if you're trying to cool the whole house down all day when it's 95 in the blazing sun vs keeping one room cool, around here that would make a difference.

It's all a moot point anyway for the OP. I doubt someone looking at a window unit vs a wall unit is going to be putting in central AC.

[trader4]

How many years would you have to run it to make back the 10 to 20X cost differential? I mean better efficiency is great, but at what cost?

[Vic Smith]

I agree with this. Only need A/C for the bedroom to sleep well. Could probably do without that too, and lay on a tiled floor if it gets too hot to sleep. Roll over once in a while to a cooler spot. No need to cool anything else. My wife disagrees.

[Han]

"HeyBub" wrote in news:xO6dndRSMLQXjrjNnZ2dnUVZ [e-mail]:

You are forgetting important advantages of not having window units. Firstly, the rooms are much lighter, less need for lighting. Secondly, if it cools a little outside, it is very easy to open the windows and get natural cooling. Try that with window units. Lastly, it is generally more comfortable and efficient for 1 whole house A/C unit than 4 or more window units. Of course, that presumes adequate insultion of the home.

[Ed Pawlowski]

One size certainly does not fit all. Your points are valid, but not deal breakers for me.

If you only have one window in a room, you are correct. If you have two or more, makes no difference to open them.

They may eliminate some light, but in a bedroom at night, who cares? I have one in the dining room on the north side and there is little light to start with and while it cools other rooms, it does not detract from their windows at all. Dining room gets plenty of light from the east side window.

In my house, it is not practical to put a central unit. There are no ducts so installation would be more costly. If I had hot air heat, I'd probably go with central. Even then, adapting later is not as good as a primary design for it.

As for efficiency, window units are generally less efficient to operate, but not necessarily more costly. Depends on how they are used. A 6000 BTU bedroom unit uses less juice overnight than keeping and entire house cooled by a central unit when only a single room needs to be cooled.

[trader4]

If you ever decide to add central air, take a look at the high velocity mini duct systems. They cost more for the eqpt, but deliver air via hoses that are maybe 2" inside diameter? Much easier to route/install in old work. I've only seen one actually in use, but it seemed pretty cool. Both the temp and the way it worked.

[George]

The efficiency is a lot better but as a side benefit it really is nice being in a space with a whisper quiet air conditioner instead of the typical drumming and loud fan noise of a window shaker.

[HeyBub]

You make some good points.

As for the rooms being lighter, that's the problem. I demand that the bedroom, at any hour, be as dark as the inside of a cow. Others may have a different view.

Open the window? In the Houston (and other similar) climates? That's crazy talk.

I agree there's a point of diminishing returns involving the number of window units and overall cost. With one bedroom, the scale, in my view, clearly tilts toward the single window unit for sleeping. With FOUR window units, the scale probably tilts the other direction.

Unless, of course, they stay OFF and are only used when the kids visit.

[krw]

Wouldn't they be noisy and drafty?

[krw]

Sounds like you don't have a view from your bedroom at all.

Mine are open for three months in the spring (March-something to June-something) and three in the fall (September-December).

When I lived in Vermont, we had two through the wall (one 2T and one 9000BTU). We didn't use them much but a cool bedroom is a must for us. We now have two central units (in each house). Each of them larger than the biggest we had in VT. OTOH, we pay significantly less for heat/AC. ;-)

Ours run continuously from June-September and December-March.

[bob haller]

in areas with cold winter weather the work and hassle of spring and fall window unit removal can become a major issue....

either remove the unit and store indoors, or leave it in and put up with drafts or the cold conducted indoors by the window unit....

in the summer a window unit means you cant just open the window on a nice day......

and when the weather is very hot and your trying to just run the bedroom window unit while your sleeping you may have to turn it on hours earlier to not only cool down the room but remove the excess moisture / humidity...

I bet anyone here that believes window units are better has never lived with central air.....

[Han]

Ed Pawlowski wrote in news: [e-mail]:

Well, guys. I live in New Jersey 07410. Last year we didn't have the A/C on much at all. This year it seems to run almost continuously. We remodeled the house, new to us, but built in 1929, a year after we bought it, 1998/9, and the walls were open enough for new siding and insulation to put in ducts and new hot water baseboard heat. I agree that otherwise it would be expensive to retrofit for AC. But I really like the central A/C as you might have gathered ... Even more now we have put foam insulation against the roof so the attic really does stay cool (~$4500 with the other energy audit things, less a 50% state refund).

[HeyBub]

Ear plugs. Fifty cents.