Crawlspace dehumidifier placement and exhaust question

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Old 06-06-17, 05:30 PM
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Crawlspace dehumidifier placement and exhaust question

I've had a couple of portable dehumidifiers fail in the crawlspace over the last 2 years (they run but both have stopped dehumidifying the air) so I'm onto the 3rd. Maybe I've had bad luck but I wanted to ask if there's anyway using an air deflector (to exhaust the air sideways) could be causing too much obstruction and damaging the units? I mean is that even possible? Should I not use a deflector?
There's only about 14 inches to the subfloor and the air exhausts right up into pockets created by the joists if I don't use the deflector. Maybe it doesn't matter but I 'seem' to get more even humidity readings across the crawlspace when using the deflector. BTW, I have a couple of gauges throughout the space and I try to keep the highest reading below 60% - I think that is acceptable (?). Anyway, deflector or no deflector, or doesn't matter ?

Thanks!
 
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Old 06-06-17, 06:00 PM
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Either the units are corroding and you are loosing the refrigerant thru a leaky coil or they are overheating and stressing the compressor.

It also sounds like you're using the dehumidifier in a very high humidity area where the unit basically runs non stop.

The air needs to move freely thru them. That air not only is dehumidified but it also cools the unit. A deflector shaped as a scoop over the top of the unit and blowing forward may be better.
 
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Old 06-07-17, 04:35 AM
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I have the dehumidifier running 2 hours twice/day. When working, it stays around 55-57%.

I have one of those clear plastic deflectors that are used on AC vents to re-direct the air.
So, you think it'd be better to use or just leave it off?
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Old 06-07-17, 06:23 AM
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Deflector

The discharge area of the deflector should be equal to or greater than the discharge area of the dehumidifier without the deflector.
 
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Old 06-07-17, 12:05 PM
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Id recommend a dehumidifier that can actually be ducted and for crawlspaces. Santa Fe Compact2 - Santa Fe - Basement and Crawl Space Dehumidifiers
 
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Old 06-07-17, 07:42 PM
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If I was going to make a scoop it would go from the back of the unit up to the floor joist.
A large gradual sweep to reduce backpressure. A light piece of tin would work.

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Old 06-08-17, 09:56 AM
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Thanks for the drawing. Problem is the distance from top of dehumidifier to the joist is only a couple of inches. In fact, the plastic deflector (if used) actually presses against the bottom of the joist. A piece of tin or cardboard would essentially be the same thing as using the deflector I believe. I mean it would still only exhaust upward approx 2" either way.
I was mainly asking if using the deflector creates some kind of obstruction which could somehow damage the unit? I wasn't sure if the air simply outputs to the area of least resistance (horizontal if deflector used) OR rather if it is indeed obstructive enough to cause some type of damage/early failure or at least decreased efficiency.
Another thought I had was placing the rear of a fan near as I can to the exhaust with the hope the dehumidified air would be better distributed across the crawlspace. I was definitely getting closer humidity readings across the crawlspace when blowing air sideways using the deflector.
 
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Old 06-09-17, 10:18 PM
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it probably cuts flow a bit.

don't worry about distribution. use deflector only to stop recirculating into the unit.

consumer dehumidifiers now are notoriously bad. You may get more life out of one if it's properly sized; if it runs all the time and never cycles off, the compressor may not last long if it's a bad quality compressor.

oversized and it will short cycle too much.

Your best bet is a american made commercial/contractor grade unit. google sante fe dehumidifier. honeywell and april-air make them too.

they're expensive, but energy efficient and durable.
 
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