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Tuksonrider 06-08-2010 12:19 PM

AC Window Unit Size, 10k or 12k?
I live in Tucson, AZ where the temp hovers around 105F+ (40.5C). It's super dry outside until monsoon season rolls around.

Anyway, my central AC doesn't seem to want to stop running. My electricity bill comes in at around $200/mo. during the summer months (which seems to be a 8 mo. season in Souther AZ.) The kicker is, my house is only 974sqf of living area. My wife is a stay at home mom and likes the air temp no higher than 74F.

As she spends most her time in the Living/Dining/Kitchen area (all connected thus ONE Room in my house), I'm really thinking about getting a Window AC Unit.

The total sq. footage I need cooled is exactly 355sqf. Just basing off sqf, an 8000-BTU unit would suffice.

Thing is:
1- There's a kitchen attached (but incredibly small, seriously)
2- Vaulted Ceilings (12ft high at it's peak)
3- The way my house is orientated, ALL exterior walls get sunlight. (Corner of my square house faces almost directly to the rising sun in summer.)
4- It gets EXTREMELY HOT in the summer time outside, BUT... my house is new-ish (built 1998), and has good insulation, and double-pane windows.

I'm THINKING about a 10,000-BTU unit, but will I better be served with a 12,000-BTU?

Though it is dry here, I don't want to lose efficiency with an over-sized unit that's not de-humidifying. On the other-hand, I don't want to run into the same situation now where the AC unit NEVER stops running.

The unit will be placed in the Dining Room (which seperates the living from kitchen area).

Help me decide!

beenthere 06-08-2010 02:14 PM

How often do you change your air filter.
Are you using a restrictive air filter like a 3M.
Has the A/C been serviced recently. As in the coils cleaned, and the charge checked.
What size is your central A/C.

Does your wife sit so that the air flow hits her?
Will the air flow from the window unit hit her?

The area you want to cool is slightly more then 1/3 of your homes total area. So you'll need a window unit that is about 1/3 the size of your central unit.

Depending how open the rest of the house is, you'll still have a high bill. Unless your going to set your thermostat to 80 for the rest of the house. Until you go to bed.

Tuksonrider 06-08-2010 03:49 PM

THanks for the reply.

1.) I change the filter every 30-days
2.) I use those cheap $1.00 filters
3.) Serviced last year (Condensor fan motor died and was replaced)
4.) I have no idea what the size is. It "looks" small. *shrugs*
5.) She moves around doing house stuff.
6.) Hoping that the prospective Window unit will cool down the room she is in (Kitchen/Dining/Living room)

That was the plan. Set the central A/C to 80 and close the doors because no one is in those rooms.

The bedrooms (2) & bathrooms(2) are closed off individually. They have doors of course, so it's not at all open like the kitchen/dining/living room is.

beenthere 06-08-2010 05:02 PM

But did they clean the coils when they replaced the fan motor? Or just replace the fan motor?

If you can isolate those rooms, it might be cheaper.

Read the model number on the outside unit, and post it here. We can tell what size it is then.

Tuksonrider 06-08-2010 05:22 PM

Oh. Since the ac guy was replacing the fan motor, we had him do a "tune-up and clean" of the entire system.

He said it was all okay. Charge was good too, as well as no duct leaks.

It does reach 74F, but with house orientation, large windows, we get very uneven cooling (even in this small house). Bedrooms are for some reason, ALWAYS cool. Kitchen is noranlly cool too as it just gets the morning sun. The living room is the hottest, as we have large sliding glass doors facing the setting sun. We keep the heavy curtains closed.

I think I need to redo some weather-stripping maybe? Hot air getting in somehow? Our house reaches 74f, and it's not at all humid inside, it just seems like as soon as the central AC cycles off, my house immediatly jumps to 75F and it kicks in again.

We got heavy curatins, UV window film, ceiling fans. Maybe I just need to move somewhere cooler. :laughing: It sucks when it's 10pm and the outside temp is near 100F

May's electric bill topped $98 and summer JUST started. :(

beenthere 06-08-2010 05:31 PM

I'm sure your house has many leaks. As is typical for most homes. Sealing those leaks will make a big difference.

Scuba_Dave 06-08-2010 06:29 PM

My electric bill without AC is over $100 :laughing:
And we don't turn the AC on unless it goes over 85 usually
Ceiling fans in every bedroom, kitchen, sunroom & main room
Try turning it up to 76

tomcat862 06-17-2010 11:35 PM

Well I just tested 3 Haier window AC I bought at Kamrt for $109 ( pre summer sale 2 months ago) for a 8,000 btu with remote this is in Helltown Tucson. Our home is 3,000 Sq FT with 2 each 3.5 ton central AC units.( older uniots with SEER of about 10( So for May this year we used just 720KWH last year we used 1700KWH.

I would buy 2 of the Haier 8,000 btu units to cool off a 400 to 500 SQ FT room when it is 104F outside like it is in helltown All AC's work with about an 25%to 30% knock down factor this is true for window AC that are built on the cheap.

I mount the window AC outside but I run flexable duct to the ac and return room air lines this way the view out of a window is not blocked and the noise is next to nothing. The remore control work throught a closed window or sliding glass Door.

For under $400 you can cool a large home and save thsi in just 2 can still use the monster central AC to cool off quick then use the small ac to mantain temp.

The Haier units come with a 5 year warrenty so i will just throw then away when they burn out its cheaper than just the checkup on the central AC.

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