AC humidity removal

In looking for a new AC, I ran across two with the same BTUs, same manufacturer, same energy efficiency, but the difference is that one removes 25% more humidity per 24 hr than the other. (Basically, that one is the new model and the other is the discontinued but-still -available-until-sold-out version of the same AC).
How can an AC be remodeled to remove more humidity?
Sue(tm) Lead me not into temptation... I can find it myself!
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Short answer yes. I had a American Standard with a VFD on the air handler. Startup of the compressor the fan would ramp up to 30%... stay there for a minute. Running 5 tons of cooling through the coil and only 30 % of the air volume it removed a lot more than a single speed unit.
Check the specs carefully if there is no other difference in the mechanical stuff, look especially at the specs for the blower and its operation.
Might be other ways to do it I know that method works.
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Larger evaporator.
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Curly Sue wrote:

Sizing down Btu/hr for more runtime, --is helpful. - udarrell
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http://www.udarrell.com/air-conditioning-total-heat-enthalpy-latent-heat.html
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Partially block the cool air output with some duct tape.
Nick
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Nick, you are so lost. Do you mean duct tape the coil? or the duct? or the grilles? You can use dampers in the grilles to lower air flow, but better would be to use a dehumidistat connected to a fan speed relay to lower the blower speed when it is humid in the house. Using duct tape to fix the problem is a bad idea. Nick, you should change your name to MacGyver!
Stretch
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One strip perpendicular to the output grill blocking ~10% will do.
Or go buy a VFD system :-) Nick
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The dampers I've seen in current window ACs only change direction.

Sounds good, with a $16 motor control, but the motor might hum at low speed, and most current window ACs use a single motor with 2 fanblades, so this would also reduce the condenser airflow.

Would you prefer an old sock? :-)
Nick
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This is Turtle.
The one that removes more humidity has a slower speed of blower to slow the air down just a little to make the evaperator coil colder which will make more moisture drop out. if you want to remove a 100% more humidity with any window unit, you just use low speed on the blower and you got a super de-humidifier. You can just slow or speed up the fan speed on the window unit to get more humidity out or less out.
The slower the air passes through the evaperator coils, the more humidity is dropped out.
The faster the air passes through the evaperator coil , the less humidity is dropped out.
TURTLE
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Try this link to a humidity control article:
http://www.contractingbusiness.com/Classes/ArticleDraw/ArticleDraw.aspx?CIDV43&HBC=GlobalSearch&OAS=&NIL lse
Stretch
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http://www.contractingbusiness.com/Classes/ArticleDraw/ArticleDraw.aspx?CIDV43&HBC=GlobalSearch&OAS=&NIL lse
OK. Try looking at Smart Vent's 12/19/2000 US patent no. 6,161,763 "Module-controlled building drying system and process" at http://www.freepatentsonline.com .
It describes "...drying air circulation between inside and outside the building based on absolute humidity and temperature sensor measurements" and claims "a programmed controller... the input ports are connected to... outside absolute humidity sensors... [and] inside absolute humidity sensors [and] the output ports are connected to... [a fan system.] ...if the outside air has a lower absolute humidity than the inside air... the fan system output will be activated... if the outside air has a higher absolute humidity than the inside air... the fan system will be shut down."
Nick
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Sounds Interesting Nick. Is it actually available and how much does it cost? Is it cheaper to operate than a dehumidifier and what is the payback period? Due to outside RH levels here in Myrtle Beach, SC I duobt that it would be effective here, but it may work very well in other climates.
Stretch
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The Smart Vent? It seems to be available, at $365.

Smart Vent says $8/year. BTW, all this was in my last posting.

Compared to what?

They say it works in Florida and Hawaii... NREL's Wilmington NC weather station has these long-term averages:
Daily min/avg/max humidity ratio deep ground: 63.4 F
Apr 50.5/62.3/74.0 F 0.0080 w May 59.3/70.1/80.8 0.0114 Jun 67.5/76.5/85.4 0.0147 Jul 71.7/80.1/88.5 0.0168 Aug 71.0/79.4/87.6 0.0167 Sep 65.3/75.3/85.2 0.0142 Oct 53.7/65.3/76.9 0.0099
Smart Vents seem very programmable. They mention 25 different control algorithms. Ventilating with outdoor air (warmer in winter and cooler in summer) at times when its humidity ratio is less than the hr of indoor air seems energy-efficeint, but I suspect that can be improved, in a fairly airtight house that can store heat and moisture.
In a house like that, with air conditioning, it seems more energy-efficient to circulate air between the basement floor and the living space than to exhaust basement air. Surrounded by RH% air, concrete stores about RH/20 % moisture content by weight, with little dependence on the air temperature.
A 4"x1000ft^2 50K pound basement floor with 8K Btu/F of thermal capacitance (or more, with no insulation below) can slowly store 500 pints of water as the RH of the basement air rises from 40 to 60%. The ground below might have an effective R10 thermal resistance.
If we keep a basement RH 60% all year, the moisture content of the concrete won't change much. Maybe it's more energy-efficient to easily lower the RH of the basement air by warming it with dry house air in wintertime to drive moisture out of the concrete so it can absorb more moisture in summertime.
Nick

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Most dehumidifiers use the hot gas as condenser reheat, so they're self-contained and require no refrigerant piping. Therefore, they're easy to install... They also add some load to your air conditioning system, because the electricity they use shows up as heat in the house.
They forgot to mention the latent heat, about 60% more than the electrical energy used, as I measured it.
Nick
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Hi snipped-for-privacy@ece.villanova.edu, hope you are having a nice day
On 18-Jun-05 At About 09:49:46, snipped-for-privacy@ece.villanova.edu wrote to All Subject: Re: AC humidity removal
n> From: snipped-for-privacy@ece.villanova.edu
n> > Try this link to a humidity control article: > n> > http://www.contractingbusiness.com/Classes/ArticleDraw/ArticleDraw . n> aspx?CIDV 43&HBC=GlobalSearch&OAS=&NILls
n> Most dehumidifiers use the hot gas as condenser reheat, so they're n> self-contained and require no refrigerant piping. Therefore, they're n> easy to install... They also add some load to your air conditioning n> system, because the electricity they use shows up as heat in the n> house.
Wrong, In the basement it is cold enough that the heat doesn't really matter. it never really warms up down there. In your world there is usually so much that you don't take into consideration that it isn't even funny.
-=> HvacTech2 <=-
... "It's a small world, but I wouldn't want to have to paint it."- s.w.
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May you be having the finest of days as well.

I just quoted the site, but it seems to me the quoted electrical gain is an underestimate. If you disagree, would you have any evidence for this peculiar article of faith? :-)
Nick
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