Central Air v. Window-unit Air?

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Are you talking about those in-wall types? *************************************************************** I have a free standing one that looks like a glass doored woodstove. It has ceramic logs inside, like a gas fireplace. They also have ones that mount to the wall. Type...........unvented gas heaters.........into Google and click "Images".
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JerryD(upstateNY)




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Window shakers come in assortment of efficiency. But, overall, I believe that central AC is more efficient.
Please ask your installer for: * Rotary compressor * TXV coil
Expect to pay a couple dollars more than a piston compressor and orifice coil. But, will pay for itself in efficiency.
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Christopher A. Young
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Stormin Mormon wrote:

If you're shopping for a central AC unit, do not ask for a rotary compressor. You'll get a curious look from the salesman. Most geo units and most window units come with rotary compressors, central units no. Did you mean *scroll*?

Yes to this. Demand a TXV coil.

hvacrmedic
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The way I figure it, rotary means that the armature and assembly goes around, rather than recip back and forth. Scroll is one of the types of rotating compressors.
Though, most guys in the trade would see it your way.
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Christopher A. Young
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If ignorance is bliss Stormy, you must be euphoric.
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If ignorance is baseball, Stormy is Babe Ruth.
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Bad analogy....Babe Ruth also struck out more often than anybody else too.
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This is Turtle.
Come On now Stormy Stop that asking for Rotory Compressors. You know it is a scroll !
TURTLE
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Rotary compressor in a central AC unit?? That I gotta see! Window shaker or a mini split perhaps, but not on a typical central air. Greg
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This is Turtle.
hey , there was a company that started using rotory compressors in central units back about 20+ years ago and their name was Fedders corp.. They started putting the rotory compressors in their central units and due to the 100% failure rate, they went belly up or bankrupt in 3 years after starting to put them in the central units.
The problem was this as to the 100% failure rates . The Mass of the shell of the compressors over 2 1/2 tons was too big to let all the heat out and not heat up too much and burn it's self up. By Now a days they must have design it right to do it by now.
TURTLE
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In 1960 GE made its first rotary (roller/vane type, I dont think it was a rotary vane, but a roller thats why it is so dependable, the vane moves in and out..thats it, it does not scrape on on a rotating surface) compressor for split system AC units in the under 2 ton range. Bullet proof. My RV has one of those in its rooftop AC from the look of it.
the Daikin brand (japanese) split system heat pumps used a roller type as well. Those went up to 5 tons ( and 4 or 5 indoor coils )
I think scroll compressors have problems in the smaller sizes because of manufacturing tolerance issues...in larger compressors the same tolerance limitations create less of a loss of efficiency (pressure leaks past the scroll)... I havent paid any attention to how small a scroll compressor is made but it seems like 3 tons?
Phil Scott

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I thought they were supposed to cool partly account of the refrigerant going through. Though, such a system might trap the heat in. I've seen compressor blankets, now. I bet those totlaly depend on refrigerant flow for cooling.
Wonder if the failure rate you saw was the warmer southern climate, or mabye someone before your time didn't do much coil cleaning?
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Christopher A. Young
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This is Turtle.
the Heat was generated in the shell of the compressor by the rotor and not as it was leaving the compressor like Scroll or piston. No Stormy Poor Design.
No Stormy , you don't have a 100% failure rate caused by too hot of weather or not cleaning the condenser. Most of the failures were the first time the system had a run 12 hours straight without turning it off to cool off. i changed one out under warranty for a chicken place here and in about a month later the rotory compressor went out again. Fedders told use to have it fixed and send the bill to a law firm in New York and see if they would get paid. The customer just bought a new condenser and forgot about it for Fedders being in bankruptsy court and all.
No i did not sell it to him for he work for a chicken fast food chain call Fatsos Fried Chicken and had a deal cut to buy wholesale of all the hvac equipment and get their installer to put it.
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On Sat, 06 Aug 2005 01:17:40 GMT, "Stormin Mormon"

I can't afford one with my ex-pension, as I am confined to orifice work. I guess I'll just have to settle for a pissed-in unit.
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-john
wide-open at throttle dot info
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i used to run 3 6000btu window units and at the time the electric bill was 125.00 in july. i put in cenral air and the electric bill was 75.00 in august . running the new larger scroll compressor was cheeper than the 3 compressors in window units, better cooling,and less hassel.lucas
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Nehmo wrote:

In your situation, I would improve the insulation situation and do everything possible to the windows and doors to reduce the heatgain. Also, do everything possible to reduce air infiltration.
Then I would go with the newer smaller 6000-Btu/hr quiet window units; like the Whirpool Quiet Partner Series with electronic cordless controls. Using a "Wind Machine 3300 | 20" fan," my little 6000 room A/C cools 920-sq. ft., three open rooms and part of the hall in 100-degree high humidity 112 to 116-heat index weather, --to 78-F or under and 55 or less percent relative humidity; very comfortable. Read my linked page on how that works:
<new>http://www.udarrell.com/airconditioner_current_temperature_btuh_charting.html
My July electric bill was $45.10; I have an electric hot water heater, electric range, a refrigerator, two TVs and a PC. I never use my old clothes dryer.
My upstairs unit is a Kenmore Cool 'N' Lite 5,950-btuh window A/C, by using another 20" floor fan on low speed, it cools one bedroom, the hallway, stairwell, and the bathroom.
I have central oil heat in a two-story home with a deep basement that was built in May of 1937, 68 years ago. The duct system was installed for a gravity airflow wood fired furnace. - udarrell - Darrell
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Factors in the Correct Sizing of Residential Air Conditioning Systems -
Recommended Procedures for Proper Duct Sizing of Residential Air Conditioning
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Sticking to the question and ignoring my personal opinions: This would take an electrical engineer doing calculations to get an accurate answer. There are many variables, the most important of which is the size of the house in question. The answer would be different for an 1800 sq ft ranch than it would be for a 4000 sq ft, 2 story house. A typical central air compressor runs on a 30 amp circuit, a typical window unit on a 15 amp. The majority of the electricity used occurs when either unit kicks on. So in either case if the units run longer and start up less often the efficiencies rise. Poorly sized central units "short cycle" and that condition greatly decreases the cost efficiency. Same is true of the window units. A larger house would require two or more compressors. In addition, central air systems require an air handler. Once again, the answer will be different if the house already has hot air heat and the A/C coil is just going to be added to it rather than a new, separate air handle installed just for the A/C. Air handlers typically run on a 15 amp circuit. Once again, one or two depending on the size of the house. So every time the central unit kicks on you've got juice running the compressors and the air handlers with the total draw being a complex calculation of the total wattage required, the initial startup surge, and the steady run-time usage. The window units do the same, but the combined wattage would need to meet or exceed the central unit to use the same amount of juice. You buy central air for convenience, comfort, and prestige. Forget about the payback. That comes when it's time to sell the house.

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I'm an EE. You got my calcs.
Nick
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NOW YOU TALKING MY LANGUAGE Dido siad that

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