SEER

Suppose I have an electric bill of $100 using a 10 SEER unit, how much lower will my bill go if I switch to a 12 SEER unit?
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If you live in a high humidity climate going to a higher SEER may not be a good idea. In my opinion the government should not be telling manufacturers' that they can not build 10 SEER condensing units.
Your "Comfort Zone" is dependent on the proper relationship between the temperature, humidity, and scores of other technical factors that could help optimize the system for maximum efficiency. Do a lot of studying, investigating, and soul searching, before you spend your money.
Those that live in very high humidity climates could get a rude awaking if they install the highest SEER units available. In those climates I would go for the lowest SEER and size to get optimally long run-time cycles. udarrell - Darrell http://www.udarrell.com/my_pages2.htm#MY_AIR_CONDITIONING_PAGES
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Air Conditioning Equipment Selection toward Controlling High Humidity
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Udarrell, Just for grinns, where are you located??
Apparently you are not located in a high humidity area, otherwise you would not have made the following statements;

A correctly sized and designed high SEER (13+ SEER) will maintain a comfort level of 75 degrees IDB with an indoor RH of 50% with no problem even when its 95/95 outside, and with a lot less energy usage than a 10 SEER system could ever dream of. Come on down to the gulf coast and we'll show you how its done.
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I never worked in a real high humidity climate. Also, SEERs have gone up since I retired. If you can keep the coil cold enough and the runtime cycles long enough a larger coil could get the job done. I will not in disagreement with that conditional situation.
If you can make the higher SEER units work better than a lower SEER system in those conditions, more power to you.
Regarding Coil Selection: "If based on a much higher operating temperature/pressure ratio of the larger coil 'in order to get the required volumetric efficiency in the smaller compressors' and still get the units rated BTUH." (Lowering the fan CFM and thus further lowering the volumetric efficiency in the smaller compressors will also produce the longer required run-time cycles in a proper sized unit.
DX-Coil size is a major factor determining the balance between Dry/sensible and latent/Wet heat removal. Evaporator coil size determines this ratio. Larger evaporator coils normally remove less humidity, because they operate at a much higher coil temperature/pressure ratio --smaller E-Coils tend to remove more humidity --because they normally operate at a much lower operating temperature.
I have another page on my website (that has been up for a long time) where I stated that: "an oversized DX-coil with airflow CFM in a range where the coil is cold enough to do an efficient job condensing moisture combined with adequate run-time cycles could be most effective at reducing humidity." (I will amend the linked page, including my former claim and your experience.) I closed my contractor business over a decade ago There is an advantage in an oversized coil in that it has more fin and coil area with which to condense moisture from the air, provided you can operate it at a low enough temperature/pressure.
I hope we get more experiences posted on this subject.
It is the necessary suction pressure to achieve the necessary volumetric efficiency of the under-sized compressors in the ultra high SEER units that I am most concerned about! Lowering the temp./pres. will lower the compressor's BTUH output. We need more input posting on this issue!
Noon-Air, I honor experiential results over older viewpoints, --I do not dispute your experienced results. udarrell
Air Conditioning Equipment Selection toward Controlling High Humidity Problems - http://www.udarrell.com/air-conditioning-engineered-for-latent-heat-removal.html ----- Original Message -----
Newsgroups: alt.hvac Sent: Thursday, March 17, 2005 11:39 AM Subject: Re: SEER

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udarrell wrote:

You are right on target. If you don't get RH control with your high efficiency system then you don't get shit, because it may not keep up on the hottest days and/or it may leave you sweating in the cool indoor air. Don't get over a 10 SEER system in high humidity regions unless your system provides some means for RH control. The Infinity system uses an ECM and two-speed compressor. At 17SEER it will get the air as dry as you want it.
I think you have at least one misconception, and that is that continuous high latent capacity is required in high humidity regions. This isn't so, since moisture requires time in order to infiltrate into the conditioned space. Intermittent operation in high latent capacity mode is all that is required, the rest of the cycle is run at high SST, providing the volumetric efficiency that you are worried about. Going with a smaller evaporator limits what you can do SEER-wise, since you will be providing for high latent capacity 100% of the time, when it is only required for a fraction of that time.
As for experience, I've been in several structures with 12-13 SEER stuff installed that were absolutely uncomfortable. Lowering the blower speed will take care of the excessive humidity, but like you said, it will kill the extra SEER, and it will sometimes reduce the system capacity a half ton or more, so that it will no longer keep up like the old 8 SEER junk did. In general I agree with most of your instincts on these topics.
Richard Perry

http://www.udarrell.com/air-conditioning-engineered-for-latent-heat-removal.html
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You may not get the particular SEER you are looking for but you can get a pretty close sensible to latent ratio if you are using a coil, furnace, condenser combo that matches your requirement
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Bob Pietrangelo
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