Dehumidifier and Airconditioning

[abstamaria]

Living in the tropics, my problem is a little different - humidity, which exceeds 80%. I keep a floor dehumidifier that reduces relative humidity to about 55%, which inhibits corrosion. Sometimes I need to run two of dehumidifiers because the garage is a bit long.

The garage is airconditioned (two 3-hp inverter ceiling mounted units). When I turn these on, humidity drops instantly. Is there a way I can use an airconditioner economically so that it cycles on and off based on humidity rather than temperature?

Many thanks.

Andres

 

[bd8134]

I have a 3 ton variable speed fan/ 2 speed ac unit. The controller enables me to set the humidity level and other options. A super dehumidify - it slows the blower fan down so the coil is colder, a fan off after cooling mode when the set temp is reached - this enables the cold damp air on the evaporator to continue dripping into the drain, etc. It also runs when there is no call for cooling if the humidity is high.
These are options on the controller itself but the compressor and fan unit need to be capable to run this. I do not suffer the high humidity you do. A 32' x 44' garage maybe 65% humidity max. It goes down to 35% when I cool the garage for a while, the water is pouring from the drain.
Running dehumidifiers causes more heat being generated in the garage and the moisture captured is still contained within the garage, unless you have an outside drain connected.
Maybe your a/c units are of the type that supports dehumidify / variable speed and you might just need a controller to enable these features.
Maybe replace one of the ac's with a unit capable of dehumidifying or add another?
Maybe other more informed suggestions?

 

[abstamaria]

Thank you, bd8134. i will check m airconditioning units. i how it has a humidity setting. I will let you know.

 

[lametec]

If your AC units don't have built in humidity control, you can buy a humidistat and wire that in place of the thermostat. Or you can buy a thermostat with humidistat built in for the best of both worlds.

 

[abstamaria]

Thank you all. I wanted to report that the 3hp inverter split units I installed in the garage do have a dehumidify mode. In that mode, the units run quietly at a low fan speed. They don't seem to be working hard at all, and one unit running is enough to keep humidity low. I understand 55% is ideal.

I haven't yet operated a unit 24/7 and use a free-standing dehumidifier for that; that adds to room heat. The 3-hp A/C unit seems more economical to run and cools the room slightly to boot. I may just try it for a month to see what impact it will have on my utility bill.

 

[bd8134]

Thats good.
An under-sized or a correctly sized AC unit will be the most effective at removing humidity and controlling temp swings. If you are just intending to lower humidity and not worry about the temperature, using just one of your 3-hp units might be the best solution.
As you said, try it for a month and monitor your wallet impact.
Some controllers when coming from dehumidify mode, turn off the fan as soon as the correct humidity level is reached. This allows the condensation on the coils to drip into the drain.