# How do you know when a central area unit is sized right?



## MechanicalDVR (Jun 23, 2007)

bjg5240 said:


> There is an attic fan installed. As far as the servicing of the unit, I did have a local hvac company come out & clean & check everything when we first purchased the home in May 2007. Other than the electronic air filter was a filthy discrace, he didnt mention anything about it being on its last let. I removed the electronic air filter & replaced it with a paper filter. I just don't think there is enough air pressure coming out of the upper vents. I tried closing off some of the lower supply's, but I havent seen much of a difference. Is there a way to install a larger blower motor without replacing the whole unit?


 
Yes and no. If you add a larger blower you will need to adjust the freon charge accordingly. Typically you base airflow on 400 cfm's per ton of a/c. If the air moves across the coil to fast it can cause condensate problems and may not have enough heat transfer. You could try having the air flow balanced but you probably just have a poor duct design.


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## Celtic (May 23, 2007)

Why do they size compressors by the "ton"?
They don't weigh that much.


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## mdshunk (Mar 13, 2005)

Celtic said:


> Why do they size compressors by the "ton"?
> They don't weigh that much.


It's an old-school unit, related to cooling of one ton of water 1 degree every 10 minutes. Related to old-time ice making. For electricians, we just need to know that 1 ton is 12,000 BTU's or one horsepower.


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## BigMikeB (Aug 1, 2007)

Celtic said:


> Why do they size compressors by the "ton"?
> They don't weigh that much.


 
No one would buy them by the pound.


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## Celtic (May 23, 2007)

Both excellent answers!

One was right...the other make laugh :laughing:, you guys decide who was who :thumbsup:


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## 747 (Jan 21, 2005)

I say a high velocity hvac system is the way to go. Example unico system. For A CA unit i say the water cooled is the way to go. More upfront cost but a dimished operating cost. You see those more in commercial applications but they do make smaller residentals units.


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## MechanicalDVR (Jun 23, 2007)

747 said:


> I say a high velocity hvac system is the way to go. Example unico system. For A CA unit i say the water cooled is the way to go. More upfront cost but a dimished operating cost. You see those more in commercial applications but they do make smaller residentals units.


If you mean water source when you say water cooled then yes, the high upfront costs are recouped and then some. If you are actually talking a water cooled unit, then the true operating costs are a looser.


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## MechanicalDVR (Jun 23, 2007)

mdshunk said:


> It's an old-school unit, related to cooling of one ton of water 1 degree every 10 minutes. Related to old-time ice making. For electricians, we just need to know that 1 ton is 12,000 BTU's or one horsepower.


Actually it's based on the btu's required to melt a ton of ice.


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## 747 (Jan 21, 2005)

MechanicalDVR said:


> If you mean water source when you say water cooled then yes, the high upfront costs are recouped and then some. If you are actually talking a water cooled unit, then the true operating costs are a looser.


Yes thats what i mean water source. I didn't know what the actual technical name was.


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## 747 (Jan 21, 2005)

MechanicalDVR said:


> If you mean water source when you say water cooled then yes, the high upfront costs are recouped and then some. If you are actually talking a water cooled unit, then the true operating costs are a looser.


Here is exactly what i mean.

http://www.freus.com/

Freus Inc (formed in 2001) has focused on air conditioning efficiency technology. The 2005 Federal Energy Bill provides a $2,000 tax credit for homes that exceed 2003 International Energy Code Standards by 50%, and Freus technology use is the most cost effective way for homebuilders to achieve that 50% efficiency increase. Freus grew Freus brand sales from $.7 million in 2003 to $2.6M in 2004 and has projected $4M in sales for 2005 (fiscal year ends September). Freus is using a novel DSM approach to sell energy savings to Utilities and provide the energy savings through new homes at no incremental cost to the builder or existing homes at no extra cost for a replacement A/C. Freus has bid Utility DSM contracts of over $1.5 billion with three Utilities, in the last few months, with installation fulfillment over the next 8 years. The annual DSM bidding opportunity is ~$8.5 billion/ year. Freus bid prices as low as $0.049/ kWh on peak (below the cheapest on peak utility peaker plant costs) and expects to be low bid on the contracts. Freus is negotiating with major A/C Manufacturers ($1B+ in sales size companies) to jointly fulfill the contracts, and has signed a secrecy agreement (with a non-compete clause) with a major manufacturer. Freus projects sales of $57 million in 2006, $152M in 2007, and $224M in 2008. Profit is projected to be $76M in 2008. Freus Inc has patented technology (2 patents w/ 18 claims issued, 19 claims pending) and manufactures Freus Air Conditioning units, which have performance certified through the Air Conditioning & Refrigeration Institute (ARI); Freus units are the most efficient air conditioners in the world. Freus units are safety certified through ETL (listed to UL Standard 1995). Four years of field studies by Paragon consultants (paid for by Nevada Power - Las Vegas utility) showed up to 65% energy savings vs. the highest volume A/C units currently being installed (reduced ~40% of total home peak electric use). Freus has its own design, tooling, and manufacturing capability. Primary offices are in Vinton (a suburb of El Paso) Texas, and Freus manufacturing is in Freus' Mexican manufacturing plant in Juarez Mexico. Funding is being sought to fund manufacturing capacity growth, working capital requirements, and place long term Utility contracts with large banking or institutional investors. Freus’ exit strategy is to be acquired by a major A/C manufacturer or do an IPO in 2008.


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## MechanicalDVR (Jun 23, 2007)

747 said:


> Here is exactly what i mean.
> 
> http://www.freus.com/
> 
> ...


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