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you have to start thinking in grains, dry the air out when it is warm with the desicant, then cool it off, even re-humidify
dry the warmer air down to the grain level you need with the desicant. Then cool it with chilled water 'warmer' than the dewpoint that you just created with the desicant.
run a humidifier when they want to increase to 80%
The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.
http://www.ductstrap.com/
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Usually it is easier to have two different pieces of equipment (two fans) for the two requirements for such an application. One has the filters and fan to meet the air rotation part and the other is the machine to satisfy the load part. That helps reduce the coil size and needs a smaller fan for that part. This system may have a problem holding the temperature to within +/- 5 degree and the humidity to within +/- 10% rh because there is only one stage. You should have four stages reduce the over capacity requirement when tracking a demand curve for such an application. It would help the energy consumption to have either a fixed plate heat-exchanger or a total enthalpy desiccant wheel so that you don't depend on the refrigeration system entirely without reclaiming anything.
Even a two stage cooling system will use 30% to 40% more energy than a four stage system when tracking a load curve. The graphs are attached.
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 Originally Posted by TalkingHead
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Even a two stage cooling system will use 30% to 40% more energy than a four stage system when tracking a load curve. The graphs are attached.
Do other people support the idea that those graphs tell what really happens? I submit that the area in the graphs, represents something other than energy used. Pretty graphs though.
Thanks to Carnak for his pictures and description. Unique and interesting.
Regards -- Pstu
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can't use a desicant wheel in the application
if it was new construction, perhaps a fixed plate renewair type of enthalpy device. Space was pretty tight, that is why it was built as a double decker and 'over and under'
Sometimes you need the reheat because it is pyschrometrically impossible to supply the air you need without it. So in addition to hot gas reheat, there is a few degrees of fan heat helping out as well.
The main coil is chilled water, so quite a bit of modulation possible, but I really only need to drop it by two degrees if there is some kind of huge latent spike.
The chilled water coil is trying to cool mixed air down to 54F , it will be close to fog, so will have a dewpoint just under 54. When keeping a space at 68F, a dewpoint just under 54 means 60% RH.
I am actually finding it easier to maintain RH under 40% than to keep it tight at 55%.
Holds temperature pretty good, within 2F at the moment. Need a couple more phases complete to get it rock solid steady.
Think about it, I am keeping a space at 68F, when it gets too humid and temp is fine, it blows 68F dry air. If it starts warming up a bit, shut off the DX.
The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.
http://www.ductstrap.com/
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No winter here either, my part load condition is like a nice summer day in Milwaukkee
The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.
http://www.ductstrap.com/
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Sweet dew dropper
Thanks for the display. Is it possible to post the psych plots of your problem and resolution?
"Christ is the Son of God Who died for the redemption of sinners and was resurrected after three days. This is the greatest truth in the universe. I die because of my belief in Christ."
Watchman Nee
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I suppose I could put one up
The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.
http://www.ductstrap.com/
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I hate those things......... I have a dozen of them look after..... lots bigger! Small condo size.....gggrrrrrrrrrr
mine have burners to keep the temp up......... grrrrrrrrrrr..........
Last edited by deux; 11-24-2009 at 01:00 AM.
Reason: by the way
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ggggggrrrrrrrrr........ gonna have nightmares now.........
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Thanks for the pics. Thats really nice setup!
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