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".
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.
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*?
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
Though, most guys in the trade would see it your way.
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
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.
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?
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?
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
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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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
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:
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
Factors in the Correct Sizing of Residential Air Conditioning Systems -
Recommended Procedures for Proper Duct Sizing of Residential Air Conditioning
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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