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#1
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Central Air v. Window-unit Air?
If a house currently has multiple window air-conditioners, are these
significantly less efficient than central air, if the house were retrofitted with it? I realize the comparison is complicated, so assume all other factors equal, and assume: the vents and their position for central air would be adequate; about half the rooms are normally in use; nobody's concerned about the window-view obstruction, etc.; Chicago climate; poorly insulated house. A companion question is, does the efficiency of air conditioners increase significantly with size? -- |||||||||||||||| Nehmo Sergheyev |||||||||||||||| |
#2
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Nehmo wrote:
If a house currently has multiple window air-conditioners, are these significantly less efficient than central air, if the house were retrofitted with it? I realize the comparison is complicated, so assume all other factors equal, and assume: the vents and their position for central air would be adequate; about half the rooms are normally in use; nobody's concerned about the window-view obstruction, etc.; Chicago climate; poorly insulated house. A companion question is, does the efficiency of air conditioners increase significantly with size? |||||||||||||||| Nehmo Sergheyev |||||||||||||||| Generally whole house will be more efficient and more trouble free as well as quieter. Windows units can be more efficient as you can zone each room, so while the individual unit may be less efficient, you may use less overall energy because it is easier to turn them off in one room. Frankly, I would go with central. -- Joseph Meehan Dia duit |
#3
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"Nehmo" wrote in message ... If a house currently has multiple window air-conditioners, are these significantly less efficient than central air, if the house were retrofitted with it? I realize the comparison is complicated, so assume all other factors equal, and assume: the vents and their position for central air would be adequate; about half the rooms are normally in use; nobody's concerned about the window-view obstruction, etc.; Chicago climate; poorly insulated house. If Chicago is as warm as I think it is, I'd go with central if possible. More efficient, quieter, more even temperatures in the house. Where I live, it becomes marginal most years. Normal summer we need AC maybe five to 8 days and maybe an additional 10 nights in just the bedroom. That makes window units far more economical compared to running a big system. In warmer climates I'd never consider window units.. |
#4
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On Fri, 05 Aug 2005 23:13:03 GMT, "Edwin Pawlowski"
wrote: "Nehmo" wrote in message ... If a house currently has multiple window air-conditioners, are these significantly less efficient than central air, if the house were retrofitted with it? I realize the comparison is complicated, so assume all other factors equal, and assume: the vents and their position for central air would be adequate; about half the rooms are normally in use; nobody's concerned about the window-view obstruction, etc.; Chicago climate; poorly insulated house. If Chicago is as warm as I think it is, I'd go with central if possible. Yeh, Chicago is famous for being **HOT** :-( More efficient, quieter, more even temperatures in the house. Where I live, it becomes marginal most years. Normal summer we need AC maybe five to 8 days and maybe an additional 10 nights in just the bedroom. That makes window units far more economical compared to running a big system. In warmer climates I'd never consider window units.. Click here every day to feed an animal that needs you today !!! http://www.theanimalrescuesite.com/ Paul ( pjm @ pobox . com ) - remove spaces to email me 'Some days, it's just not worth chewing through the restraints.' 'With sufficient thrust, pigs fly just fine.' HVAC/R program for Palm PDA's Free demo now available online http://pmilligan.net/palm/ |
#5
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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. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "Nehmo" wrote in message ... If a house currently has multiple window air-conditioners, are these significantly less efficient than central air, if the house were retrofitted with it? I realize the comparison is complicated, so assume all other factors equal, and assume: the vents and their position for central air would be adequate; about half the rooms are normally in use; nobody's concerned about the window-view obstruction, etc.; Chicago climate; poorly insulated house. A companion question is, does the efficiency of air conditioners increase significantly with size? -- |||||||||||||||| Nehmo Sergheyev |||||||||||||||| |
#6
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Stormin Mormon wrote: Window shakers come in assortment of efficiency. But, overall, I believe that central AC is more efficient. Please ask your installer for: * Rotary compressor 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*? * TXV coil Yes to this. Demand a TXV coil. Expect to pay a couple dollars more than a piston compressor and orifice coil. But, will pay for itself in efficiency. hvacrmedic |
#7
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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. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "RP" wrote in message ... Stormin Mormon wrote: Window shakers come in assortment of efficiency. But, overall, I believe that central AC is more efficient. Please ask your installer for: * Rotary compressor 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*? * TXV coil Yes to this. Demand a TXV coil. Expect to pay a couple dollars more than a piston compressor and orifice coil. But, will pay for itself in efficiency. hvacrmedic |
#8
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"Stormin Mormon" wrote in message ... 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. If ignorance is bliss Stormy, you must be euphoric. |
#9
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"Noon-Air" wrote in message ... "Stormin Mormon" wrote in message ... 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. If ignorance is bliss Stormy, you must be euphoric. If ignorance is baseball, Stormy is Babe Ruth. |
#10
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"Stormin Mormon" wrote in message ... 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. -- Christopher A. Young This is Turtle. Come On now Stormy Stop that asking for Rotory Compressors. You know it is a scroll ! TURTLE |
#11
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"Stormin Mormon" wrote in message ... 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. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com 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 |
#12
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"Greg O" wrote in message ... "Stormin Mormon" wrote in message ... 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. -- Christopher A. Young 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 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 |
#13
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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? -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "TURTLE" wrote in message . .. 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 |
#14
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"Stormin Mormon" wrote in message ... 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? -- Christopher A. Young 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. TURTLE |
#15
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"TURTLE" wrote in message . .. "Greg O" wrote in message ... "Stormin Mormon" wrote in message ... 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. -- Christopher A. Young Rotary compressor in a central AC unit?? That I gotta see! 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 Window shaker or a mini split perhaps, but not on a typical central air. Greg 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 |
#16
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Installing central air costs a lot of money. Once it's installed, the
cost of running it is less than the cost of what you have now. However, it would take more than 30 years to make up the cost. It could even take more than 100 years. In other words, if it costs you $1000 a year to run window units and $800 a year to run central air that's a savings of $200. However, if central air costs $6,000 to install, it will take 30 years times $200 a year for you to get your money back. So if you are comfortable now, don't change. If you are hot now, consider the money. |
#17
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wrote in message
ups.com... Installing central air costs a lot of money. Once it's installed, the cost of running it is less than the cost of what you have now. However, it would take more than 30 years to make up the cost. It could even take more than 100 years. In other words, if it costs you $1000 a year to run window units and $800 a year to run central air that's a savings of $200. However, if central air costs $6,000 to install, it will take 30 years times $200 a year for you to get your money back. So if you are comfortable now, don't change. If you are hot now, consider the money. This is Turtle. If you think a standard hvac system would cost about $6K. I need to move my business to your area and open back up for I like the way you think. TURTLE |
#18
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TURTLE wrote: wrote in message ups.com... Installing central air costs a lot of money. Once it's installed, the cost of running it is less than the cost of what you have now. However, it would take more than 30 years to make up the cost. It could even take more than 100 years. In other words, if it costs you $1000 a year to run window units and $800 a year to run central air that's a savings of $200. However, if central air costs $6,000 to install, it will take 30 years times $200 a year for you to get your money back. So if you are comfortable now, don't change. If you are hot now, consider the money. This is Turtle. If you think a standard hvac system would cost about $6K. I need to move my business to your area and open back up for I like the way you think. Are you still in the business Turtle? 6K is a normal median price. Some are less, some more. You can't touch an Infinity system for 6K, nor even just a 13SEER 410-A over 3.5 tons. hvacrmedic |
#19
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RP wrote: TURTLE wrote: wrote in message ups.com... Installing central air costs a lot of money. Once it's installed, the cost of running it is less than the cost of what you have now. However, it would take more than 30 years to make up the cost. It could even take more than 100 years. In other words, if it costs you $1000 a year to run window units and $800 a year to run central air that's a savings of $200. However, if central air costs $6,000 to install, it will take 30 years times $200 a year for you to get your money back. So if you are comfortable now, don't change. If you are hot now, consider the money. This is Turtle. If you think a standard hvac system would cost about $6K. I need to move my business to your area and open back up for I like the way you think. Are you still in the business Turtle? 6K is a normal median price. Some are less, some more. You can't touch an Infinity system for 6K, nor even just a 13SEER 410-A over 3.5 tons. BTW, given that the OP apparently needs ductwork too, well, Awwwwww hvacrmedic |
#20
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"RP" wrote in message ... RP wrote: TURTLE wrote: wrote in message ups.com... Installing central air costs a lot of money. Once it's installed, the cost of running it is less than the cost of what you have now. However, it would take more than 30 years to make up the cost. It could even take more than 100 years. In other words, if it costs you $1000 a year to run window units and $800 a year to run central air that's a savings of $200. However, if central air costs $6,000 to install, it will take 30 years times $200 a year for you to get your money back. So if you are comfortable now, don't change. If you are hot now, consider the money. This is Turtle. If you think a standard hvac system would cost about $6K. I need to move my business to your area and open back up for I like the way you think. Are you still in the business Turtle? 6K is a normal median price. Some are less, some more. You can't touch an Infinity system for 6K, nor even just a 13SEER 410-A over 3.5 tons. BTW, given that the OP apparently needs ductwork too, well, Awwwwww hvacrmedic This is Turtle. I don't know of any single hvac system that cost $6K as of now or in history of Oakdale. There is 3 -- 410-A systems in oakdale and all 3 of them are not working. We had a local install them and they don't work right. He has not got paid for them yet and is being sued. The highest bid i know of was $5,300.00 for a 5 ton 13 seer rheem heat pump for a small Church and plenty of ductwork. now if you get commercially the money goes up and $6K is nothing for a job. Now all residentiually job are poor boy stuff and is low ball, city. We have one hvac fellow who trys to get $250.00 off a complete system change out of 4 or 5 tons. TURTLE |
#21
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"RP" wrote in message ... RP wrote: TURTLE wrote: wrote in message ups.com... Installing central air costs a lot of money. Once it's installed, the cost of running it is less than the cost of what you have now. However, it would take more than 30 years to make up the cost. It could even take more than 100 years. In other words, if it costs you $1000 a year to run window units and $800 a year to run central air that's a savings of $200. However, if central air costs $6,000 to install, it will take 30 years times $200 a year for you to get your money back. So if you are comfortable now, don't change. If you are hot now, consider the money. This is Turtle. If you think a standard hvac system would cost about $6K. I need to move my business to your area and open back up for I like the way you think. Are you still in the business Turtle? 6K is a normal median price. Some are less, some more. You can't touch an Infinity system for 6K, nor even just a 13SEER 410-A over 3.5 tons. BTW, given that the OP apparently needs ductwork too, well, Awwwwww hvacrmedic Ductwork is extra |
#22
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"Are you still in the business Turtle? 6K is a normal median price.
Some are less, some more. You can't touch an Infinity system for 6K, nor even just a 13SEER 410-A over 3.5 tons. " And of course it all depends on where you're starting from. If the house has a modern forced air heating system, it;s one thing. If it has hot water heat, then it's a different story. |
#23
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wrote in message ups.com... "Are you still in the business Turtle? 6K is a normal median price. Some are less, some more. You can't touch an Infinity system for 6K, nor even just a 13SEER 410-A over 3.5 tons. " And of course it all depends on where you're starting from. If the house has a modern forced air heating system, it;s one thing. If it has hot water heat, then it's a different story. Yeah lotsa hot water heating systems in Louisiana is my bet. -- SVL |
#24
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"RP" wrote in message ... TURTLE wrote: wrote in message ups.com... Installing central air costs a lot of money. Once it's installed, the cost of running it is less than the cost of what you have now. However, it would take more than 30 years to make up the cost. It could even take more than 100 years. In other words, if it costs you $1000 a year to run window units and $800 a year to run central air that's a savings of $200. However, if central air costs $6,000 to install, it will take 30 years times $200 a year for you to get your money back. So if you are comfortable now, don't change. If you are hot now, consider the money. This is Turtle. If you think a standard hvac system would cost about $6K. I need to move my business to your area and open back up for I like the way you think. Are you still in the business Turtle? 6K is a normal median price. Some are less, some more. You can't touch an Infinity system for 6K, nor even just a 13SEER 410-A over 3.5 tons. hvacrmedic Ductwork is extra |
#25
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Nevermind move the business, just send me some of your customers.
-- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "TURTLE" wrote in message ... wrote in message ups.com... However, if central air costs $6,000 to install, This is Turtle. If you think a standard hvac system would cost about $6K. I need to move my business to your area and open back up for I like the way you think. TURTLE |
#26
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"Stormin Mormon" wrote in message ... Nevermind move the business, just send me some of your customers. Ya....Send him the one's you hate. |
#27
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"B-Hate-Me" BHateMe@home wrote in message ... "Stormin Mormon" wrote in message ... Nevermind move the business, just send me some of your customers. Ya....Send him the one's you hate. Just send him some....Turtle deals with ****ers too stupid to care who works on their ****, and Chris is perfect for ****ing them out of every damn dollar they make.. Chris and Terry are the reasons that the general public looks down on the HVAC biz as a whole....they dont know what they are doing, cant repair anything, and when they do, they have to ask what kind of freaking CLEANER to use, after making wild claims about being in the trade since they were SIX. Terrys dad should have been locked up due to child labor laws....or at least, for making such a stupid ****er in the first place. |
#28
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We can't *see* it from here. Call your local, *competent*, licensed,
insured, professionally trained, HVAC technician to do a complete assesment of what your home requires so that it can be fitted with a complete comfort system and what the cost vs payback is for you home. In this neck of the woods, the payoff is pretty quick (roughly 5 years) for a complete high efficiency comfort system. "Nehmo" wrote in message ... If a house currently has multiple window air-conditioners, are these significantly less efficient than central air, if the house were retrofitted with it? I realize the comparison is complicated, so assume all other factors equal, and assume: the vents and their position for central air would be adequate; about half the rooms are normally in use; nobody's concerned about the window-view obstruction, etc.; Chicago climate; poorly insulated house. A companion question is, does the efficiency of air conditioners increase significantly with size? -- |||||||||||||||| Nehmo Sergheyev |||||||||||||||| |
#29
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Noon-Air wrote:
We can't *see* it from here. Call your local, *competent*, licensed, insured, professionally trained, HVAC technician to do a complete assesment Try to find one who can spell :-) "Nehmo" wrote: If a house currently has multiple window air-conditioners, are these significantly less efficient than central air, if the house were retrofitted with it? Maybe, but they cost a lot less, with no ducts or concrete pads or plumbing or special electrical wiring, and low-cost Chinese and Korean labor, vs local HVAC criminals. At $69 for 5340 Btu/h at 10.2 EER (Daewoo), a 3-ton system is $69x36K/5340 = $465.17. And if one breaks, the rest keep working. ...about half the rooms are normally in use; So you might close the doors and only AC those rooms, effectively doubling the SEER of the window units, compared to central air. An X10 system with occupancy sensors might do this automatically. A companion question is, does the efficiency of air conditioners increase significantly with size? Yes, by law :-) Nick |
#30
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wrote in message ... Maybe, but they cost a lot less, with no ducts or concrete pads or plumbing or special electrical wiring, and low-cost Chinese and Korean labor, vs local HVAC criminals. At $69 for 5340 Btu/h at 10.2 EER (Daewoo), a 3-ton system is $69x36K/5340 = $465.17. And if one breaks, the rest keep working. The downside to window shakers- 1) Security...Your home is easily accessed if the burglar simply removes the unit. 2) Noise...Why do you think they are called "window shakers"? 3) Convenience...Twice a year you'll be humpin' those suckers in and out. 4) Money...I don't make any money from window shakers. |
#31
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In article , B-Hate-Me says...
wrote in message ... Maybe, but they cost a lot less, with no ducts or concrete pads or plumbing or special electrical wiring, and low-cost Chinese and Korean labor, vs local HVAC criminals. At $69 for 5340 Btu/h at 10.2 EER (Daewoo), a 3-ton system is $69x36K/5340 = $465.17. And if one breaks, the rest keep working. The downside to window shakers- 1) Security...Your home is easily accessed if the burglar simply removes the unit. 2) Noise...Why do you think they are called "window shakers"? 3) Convenience...Twice a year you'll be humpin' those suckers in and out. 4) Money...I don't make any money from window shakers. How about if they're mounted in the wall? Banty |
#32
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On 6 Aug 2005 09:30:04 -0700, Banty wrote:
In article , B-Hate-Me says... wrote in message ... Maybe, but they cost a lot less, with no ducts or concrete pads or plumbing or special electrical wiring, and low-cost Chinese and Korean labor, vs local HVAC criminals. At $69 for 5340 Btu/h at 10.2 EER (Daewoo), a 3-ton system is $69x36K/5340 = $465.17. And if one breaks, the rest keep working. The downside to window shakers- 1) Security...Your home is easily accessed if the burglar simply removes the unit. Bull****. Pulling a unit FROM THE OUTSIDE is a LOT harder than just breaking a window or kicking in a door. 2) Noise...Why do you think they are called "window shakers"? Mere derogation. They can in fact be very VERY quiet. 3) Convenience...Twice a year you'll be humpin' those suckers in and out. And on your birthday ? But seriously - no need for that at all. A simple winter cover works just fine. 4) Money...I don't make any money from window shakers. Oh well. How about if they're mounted in the wall? Banty Click here every day to feed an animal that needs you today !!! http://www.theanimalrescuesite.com/ Paul ( pjm @ pobox . com ) - remove spaces to email me 'Some days, it's just not worth chewing through the restraints.' 'With sufficient thrust, pigs fly just fine.' HVAC/R program for Palm PDA's Free demo now available online http://pmilligan.net/palm/ |
#33
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Banty wrote:
In article , B-Hate-Me says... wrote in message ... Maybe, but they cost a lot less, with no ducts or concrete pads or plumbing or special electrical wiring, and low-cost Chinese and Korean labor, vs local HVAC criminals. At $69 for 5340 Btu/h at 10.2 EER (Daewoo), a 3-ton system is $69x36K/5340 = $465.17. And if one breaks, the rest keep working. The downside to window shakers- 1) Security...Your home is easily accessed if the burglar simply removes the unit. You can put locks on the windows so they can't raise them. With locks, it wouldn't be easy to get one out without making a lot of racket. 2) Noise...Why do you think they are called "window shakers"? I bought a Whirlpool Quiet Partner Series; it is very quite. It is in the window of the living room where I watch TV; the one I had there was noisy and interfered with TV enjoyment! 3) Convenience...Twice a year you'll be humpin' those suckers in and out. My two are each 6000-Btu/hr or less; easy to install; some leave the bigger units in the window the year round. 4) Money...I don't make any money from window shakers. I agree with you on the money point. I also love to see and feel the performance of a central system that is really delivering to its rated Btu/hr specs. How about if they're mounted in the wall? Banty - udarrell -- Factors in the Correct Sizing of Residential Air Conditioning Systems - Recommended Procedures for Proper Duct Sizing of Residential Air Conditioning Systems http://www.udarrell.com/proper_cfm_b...syste ms.html |
#34
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"Nehmo" wrote in message ... If a house currently has multiple window air-conditioners, are these significantly less efficient than central air, if the house were retrofitted with it? Window AC's typically 10 to 12 SEER (Seasonal Energy Efficiency).. 12 is not bad... 10 is not so hot. You can buy central AC's at 14 Seer thats hot. However there are losses with duct work in a central AC that you dont have in window AC. (depending on duct leaks etc etc. in the 5 to 10% range...not so good actually) Window AC's are dirt cheap to install compared to central AC's and provide good 'zone control' so can be a lot less expensive to operate than central AC Home resale will be better with central AC of course. I realize the comparison is complicated, so assume all other factors equal, and assume: the vents and their position for central air would be adequate; about half the rooms are normally in use; nobody's concerned about the window-view obstruction, etc.; Chicago climate; poorly insulated house. A companion question is, does the efficiency of air conditioners increase significantly with size? No..efficiency goes down with size because its running partially loaded most of the time. The window AC's will be most cost effective across the boards especially if you buy the high efficiency models (and go to heat pump window AC's)... zone control is a major advantage with multiple window AC's Phil Scott HVAC contractor/ mech engr since 1905 -- |||||||||||||||| Nehmo Sergheyev |||||||||||||||| |
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"Phil Scott" wrote in message ... Phil Scott HVAC contractor/ mech engr since 1905 So your 100 years old now ?? -- SVL |
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"PrecisionMachinisT" wrote in message ... "Phil Scott" wrote in message ... Phil Scott HVAC contractor/ mech engr since 1905 So your 100 years old now ?? Satire. Willis Carrier didn't come up with refrigerated AC until the 1905's or something like that.. Earlier we had steam jet refrigeration (a high pressure steam venturi side port, at approx 28" water column (vacuum) was connected to a large evaporating tank, water evaporate and cooled to 40F or so and that was pumped around to air coils... prior that that goes back to BC egypt, importing ice from Mt Kilimanjaro, into deep caves the cool air circulated through the palace. The Montgomery Ward Store in Sacramento Calif though had an ammonia chilled water system as late as 1967 that I am aware of, it was still operating the last time I worked on it. It dated from the turn of the century 1915 as a guess.. Two 50 ton baker 200 rpm reciprocating compressors driven by synchronous DC motors..(multple coils around a rotor, looks like an old radial airplane motor.) The Budweiser micro breweries built in the 70's used similar machines, approx 4,000 tons total of horizontal Baker reciprocating compressors, 200 RPM DC sychronous motors.. ammonia. Why you might ask? Ammonia is the most efficient refrigerant bar none in those temp ranges. by a very wide margin. and because... volumetric efficiency goes way up with the ultra long stroke and proportionately reduced head space volume of those huge slow long stroke compressors. The suction lines on those plants were 24" main header... 10" to each of the Baker recips. Latest addition though were 1000 hp Frick screws (made in Germany). These are 3 stage cascade/ compound systems.. two compound ammonia stages, the lowest stage ammonia evaporator acting as the condenser for a CO2 system to minus 110F...(200 hp of Vilter reciprocating compressors, 1750 rpm, 480volt conventional squirel cage motors... all built nicely into one large machine building ( 300' square approx) with natural gas fired boilers...so that if there is a suitably sized ammonia leak, to the explosive limit ranges, the boiler pilots lite off the vapor cloud and make for interesting times in the vicinity..releasing about 8,000 lbs of ammonia to the atmosphere. The CO2 as liquified at -110F under pressure for use in carbonating the beer..(not 100% naturally carbonated that stuff) With large scale ammonia systems there are issues of liquid slugs in long suction lines, with pressure behind them and suction pressures approaching zero psig ahead of them.. slug velocity can reach over 700 mph. Such a 'slug' of liquid hits an elbow or end cap and blows it off ... releasing the entire charge of ammonia to the atmosphere. clearing the sinuses of a few thousand people it doesnt kill and ****ing off the local authorities entirely...most older systems were not built with the super sonic slug scenario in mind. Now a question? What do you think happens to an all steel ship, with frozen storage holds 6 decks deep, below the water level, with only the outside of envelope of the holds insulated, not the steel plates between the holds...those welded solid of course across the hull. Thats exciting. Phil Scott Phil Scott -- SVL |
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"Phil Scott" wrote in message ... Now a question? What do you think happens to an all steel ship, with frozen storage holds 6 decks deep, below the water level, with only the outside of envelope of the holds insulated, not the steel plates between the holds...those welded solid of course across the hull. Thats exciting. Phil Scott No it's not. What thrills you about modern steels used at low temperatures? It's an everyday occurance. Don't be so afraid. JTMcC. |
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"JTMcC" wrote in message news "Phil Scott" wrote in message ... Now a question? What do you think happens to an all steel ship, with frozen storage holds 6 decks deep, below the water level, with only the outside of envelope of the holds insulated, not the steel plates between the holds...those welded solid of course across the hull. Thats exciting. Phil Scott No it's not. What thrills you about modern steels used at low temperatures? It's an everyday occurance. Don't be so afraid. JTMcC. Exciting is breaking 10 feet thick, multi-year ice with a steel ship hull in the Arctic. |
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"JTMcC" wrote in message news "Phil Scott" wrote in message ... Now a question? What do you think happens to an all steel ship, with frozen storage holds 6 decks deep, below the water level, with only the outside of envelope of the holds insulated, not the steel plates between the holds...those welded solid of course across the hull. Thats exciting. Phil Scott No it's not. What thrills you about modern steels used at low temperatures? It's an everyday occurance. Don't be so afraid. You didnt answer the question. I do. I met the design builder in Honolulu two months later. So tell me what happened in this case. It was in alaska approx 1981. Smart remarks dont count, just an outcome and what would cause that outcome. Many people I talk to in this business know instantly what will happen in a case like that. Phil Scott JTMcC. |
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 On Sat, 6 Aug 2005 02:02:27 -0700, "Phil Scott" wrote: (lots of other good stuff snipped) slug velocity can reach over 700 mph. Hard to believe, but conceivable. Kinda like water hammer on steroids. :-) -----BEGIN PGP SIGNATURE----- Version: PGP 7.1 iQA/AwUBQvakEwIk7T39FC4ZEQLaJACg/1ild3wmDxPF44nW95AuvKpNa3gAnA/0 8sziXWeY2RlsF6oXM8jmT+ai =95hx -----END PGP SIGNATURE----- -- -john wide-open at throttle dot info |
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