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Old 04-04-2014, 10:27 AM   #1
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Window Unit(s)


Would it be more beneficial to have 1 - 24,000 BTU Window AC or 2 - 12,000 BTU Window ACs at opposite ends of the house? I am looking to save money cooling so IDK if running 2 units would be better even though the cool air would be better distributed. We are just trying to find the cheapest, yet wisest option until next summer. Trying to consider purchase & operating costs.

Any help would be great! Thank you in advance

Background info: We have an 1800 sq ft brick house w/ a new metal roof. The house is an open floor plan (living room, kitchen, dining are all 1 big room approx. 1200 sq ft) with the bedrooms & bathrooms separated. We foamed all the walls including the interior walls. However, we have not foamed the attic so there is no insulation there. We have about half the house shaded. We usually have 85 April going past 100 late July and all of August. The children and I are home most all the time. We currently are looking to purchase window unit(s) to get by this year until we install a central unit next year. And of course in between that we are foaming the attic probably during the fall.

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Old 04-04-2014, 11:13 AM   #2
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One of the things to understand about a window ac is that they are designed and built to be attractive, not necessarily efficient , but you can help the unit be efficient. The first problem is that window units tend to create a micro climate right in front of the unit. This is because the cool air coming out is often sucked right back into the unit and thus the warm air in the rest of room(s) does not get a chance to get cooled. I have successfully cooled a buddy’s shop (14 x 30) with a single 9000 btu unit. We added a shelf between the warm air intake and the cold air output. On this shelf we put a small high velocity fan (a Honeywell vornado, if memory serves) The shelf kept the cool air from re-entering the unit and the fan helped to disperse the cool air much further into the area. We also used a second fan on the floor at the far end of the shop to move the air on the floor back to the unit. Worked great in Phoenix, so it should work for your place too. Not having seen your home, I suspect that the 1200 foot room will be fairly easy to cool (with the shelf and the fan), but the bedrooms might be a bit harder. I would suggest fans in these rooms to pull air in from the hall way and that the second unit be placed so that it cools the hallway if possible. A floor plan would help us all understand what you are trying to cool!!!

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Old 04-04-2014, 04:52 PM   #3
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Thanks. Here is a rough sketch of the floor plan
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Old 04-04-2014, 05:25 PM   #4
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Window Unit(s)


might slide in a 115V 12,000 BTU unit,but the 24K is going to need 230V rewire from the CB panel...might end up with even a pair of 12K units needing a 230V sockets?might consider ductless install
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Old 04-04-2014, 05:27 PM   #5
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We thought about the ductless, but in the end I don't want to look at them every day. Other than that I like them. The window units are just for this season then next year we will install a central. We already have the ductwork ran in most of the house.
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Old 04-04-2014, 05:37 PM   #6
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The Ductless are going to look the same as if you had Window units. Since the Attic is not finished, nor is it insulated, the best plan is to place duct work up in the attic, then seal any openings into it, then blow in insulation in the joist bays, to help keep the house cool in the Summer, warm in the Winter.

How much head room is up in the attic?
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Old 04-04-2014, 06:18 PM   #7
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2 units may be better as you will be more comfortable and able to turn them to a higher temp. 1 unit and you may have to crank it down further just to get the further away rooms comfy. In the long run 2 units may break down more and be less efficient but for 1 yr it won't matter and you will be selling them B4 they break down. Get the cheapest 12,000 BTU units as they all will last a year. Even WalMart sells them.
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Old 04-04-2014, 08:53 PM   #8
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Quote:
Originally Posted by gregzoll View Post
The Ductless are going to look the same as if you had Window units. Since the Attic is not finished, nor is it insulated, the best plan is to place duct work up in the attic, then seal any openings into it, then blow in insulation in the joist bays, to help keep the house cool in the Summer, warm in the Winter.

How much head room is up in the attic?
It is a hip roof. We really aren't prepared until fall to do the insulation. We heated with only wood all winter without it - all we did was cut wood all winter every free moment
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Old 04-05-2014, 04:34 AM   #9
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I agree , the insulation in the attic will be the largest / quickest $$$ pay back .

I put a 12,000 btu Mini Split in for my living room / dinning room . I love it ! It is an A/C + Heat Pump .

It is quite ! :-) Much quieter than a window shaker . I think , more attractive . As energy efficient as the central air , probably a little more ? No duct loss .

Runs on 120 VAC , but that is not a big issue for me .

Biggest drawback is cost . More $$$ than a window shaker . :-(

I think , if you installed 2 mini splits , , you would decide to keep them . The high SEER units will probably be much cheaper to operate than central air . They are available in 20 + SEER models , at a price . I bought a cheaper 13 SEER unit . Which may have been a mistake . The higher SEER units would have qualified toe a tax credit / subsidy .

But , if you go window shakers , I would buy two 12,000 units , and put them at opposite ends of the room , as you described . As has been suggested , small fans will help quite a lot . You could set the 2 tstats a couple of degrees different and have them function as stage 1 and stage 2 cool .

God bless
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Old 04-05-2014, 07:39 AM   #10
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They make central air units from 13 to 21 and up to 25 SEER and the OP already has ductwork.
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Old 04-05-2014, 03:31 PM   #11
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My central unit is 13 SEER . The HIGH SEER central units are astronomically $$$ ?

As far as the duct work ..........

God bless
Wyr

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Old 04-14-2014, 07:30 PM   #12
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Two units will allow running at lower capacity by running one continuously. That will give better humidity control if you live in a humid area. For the same reason, get window units that allow you to cycle the blower off when the compressor turns off.

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