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Author Topic: Has anyone overcome the approx 100F temp limit of a consumer dehumidifier?  (Read 1061 times)

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Offline MikeySP

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Hello everyone.

What is the reason a household dehumidifier has a max operating temp of about 100F? 

Has anyone overcome this? How?

I am not sure if it is a design limitation based on gas used, hardware, or a thermal safety switch that could be bypassed.

Has anyone double stacked humidifiers to increase performance? Worthwhile results?

Thank you.

-Mike



Offline Southside

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Pretty much every consumer grade electrical component has a 40C or 104F high limit thermal cut out for safety concerns.  
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Offline kelLOGg

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I have to live with that low limit, too. I operate my dehum on a thermostat that cycles between ~88 to 95 and leave it running until the wood is dry. Takes longer than I'd like but that is the way it is.
When i sterilize i remove the DH unit from the kiln.
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Offline K-Guy

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If you can find the thermal overload and bypass it you can but you have removed an important safety, do so at your own risk!

Also if there is a fire and your insurance finds out about it, they could cancel your coverage.

If you still disconnect it know that you are using it beyond its design parameters and that will shorten its life most likely.
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Offline kelLOGg

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I used to let my DH unit reach the max temp which was about 140F which greatly shortened its life. That's why I keep it around 90 and let it run longer.
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Offline Marshall7199

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I know this is an older topic but searching as well for a DH use in higher temps.  I have found the big box DH simply stop pulling moisture out of the air at higher temps.

Anyone found a brand or technology to overcome this?
Rookie learning from the masters.

Online JoshNZ

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From my understanding of the way a dehumidifier works it has to bring the temp of the air it's working on way down low, so it's saturation point becomes low and it lets go of its water. Then heats it back up and fires it out the door.

I can imagine above a certain temperature environment, you will be outside the range of where it can actually bring it down cool enough to have any effect anyway, particularly a home appliance model that should never see more than 100F or so.

It'd be easy to rip the electronics out and just power the hardware via a manual switch but you may have the limitation of above anyway.

Offline peakbagger

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The alternative to using an evaporative type de-humidification is go with a lithium chloride liquid desiccant system. I worked with a candy company a few years ago, they pumped the desiccant around the plant to the candy rooms and then used a spray type scrubber to dry the air out in the room. It drys the air right out and then the used desiccant is recycled.    

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When you put residential style hvac equipment in a hot environment it wasn't designed for the pressures, especially on the high side, increase to the point of self destruction if not equipped with temp or pressure sensors to shut compressor off. Conversely, when asked to cool below its' deign point, the low side has issues like freezing evaporator coil and such. There are ways to get more, or less from them, but reliability suffers greatly. Nyle and maybe others design everything in their units to withstand extremes and still function, but even they have limits on ambient conditions.
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Offline Marshall7199

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I too have found the typical compressor based DH stopped producing in the 90 deg range.
I have started my search for a desiccant type dehumidifier.  In doing a bit of web research, I  found the desiccant has a low and higher temp threshold, and does not generate the heat that the compressor based DH produces.  I do not care about the lower limit as i can activate the heat lamps to bring the chamber up to temp in the winter.  The big box stores do not stock them so I am struggling with finding one.  
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Offline mike_belben

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The alternative to using an evaporative type de-humidification is go with a lithium chloride liquid desiccant system. I worked with a candy company a few years ago, they pumped the desiccant around the plant to the candy rooms and then used a spray type scrubber to dry the air out in the room. It drys the air right out and then the used desiccant is recycled.    
Another option is sodium polyacrylate aka polymer crystals aka dyper dessicant aka damprid aka miracle grow water storing crystals.  Same stuff in the fancy cooling headbands and stuff.  

A one time bulk purchase could be split into a few batches to rotate.  I would try making a miners type screen framed box to sit over a box fan turned ap at the sky and maybe suspended from the ceiling on wires or joists so that it is blowing wet air through the screen and crystals.  

Theyll swell into watery snots when saturated.  You dump them out a trampoline or tarp or piece of tin or something in the sun to dry back to rock salt sized granules then collect and reuse.  Theyll take a lot of water.  


A piece of gutter lined with crystals as a trough and a board over it to make that into and air duct could have wet air circulated by a little 3" round vent booster fan and some dryer ducting.  Cut a bondo spreader to squeegie the wet gel into a bucket and refill.  
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Offline cabindoc

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I too have found the typical compressor based DH stopped producing in the 90 deg range.
I have started my search for a desiccant type dehumidifier.  In doing a bit of web research, I  found the desiccant has a low and higher temp threshold, and does not generate the heat that the compressor based DH produces.  I do not care about the lower limit as i can activate the heat lamps to bring the chamber up to temp in the winter.  The big box stores do not stock them so I am struggling with finding one.  
Maybe you need to add aux heat.  Heat lamps or ??  I have a small kiln I use for small pieces and have a consumer DH in it along with 2 250w heat lamps and it will heat the chamber to 115 and pull water like no ones business...until it doesn't  I get about 12 cycles and then it craps out and I go buy another one.  It also a limit as to how low it will bring the chamber in terms of RH.  The current unit only goes to 40%RH in the chamber.    
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Offline Don P

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What is the difference in a home dehumidifier and a DH kiln unit? Is it running different pressures or  ???.
The future is a foreign country, they will do things differently there - Simon Winchester

Offline mike_belben

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Probably country of origin!
Isaiah 63:10

Offline firefighter ontheside

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Consumer DH's are known not to last a long time in a kiln environment.  I imagine that would be even worse if you push it past its limitations.  My DH that has been in my kiln for about 9 months is starting to not work well.  The coils ice up on me.
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Offline YellowHammer

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There are several differences, and the basic design is the same, but more closely leans toward the system found in a car rather than a home consumer system.

From a cycle standpoint, due to the extremes of the kiln environment, the system is configured more like an automotive system, which must operate to very high inside temperatures swings such as a hot car in the summer, vs a house unit, which sees very little inside temperature swing.  Even the refrigerant used in the DH Kiln is R134a or a blend of it, which is an automotive refrigerant.

The guts of the DH system is much more robust than a conventional homeowner system, with the parts and pieces designed and manufactured to withstand the higher temperatures and corrosive environment.  For example, the coils are very expensive (they cost more than the compressor, I know, I've had to replace both through the years) and are coated with a type of non corrosive ceramic.  Even the fan motors are different, and are rated for higher operating temperatures, including the material used in the blades and even the grease for the bearings.

With a kiln, you get what you pay for, and don't tell Stan at Nyle this :D :D, K-Guy or he'll get the big head, but Nyle builds real nice units that last a long time.  
YellowHammerisms:

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Offline K-Guy

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don't tell Stan at Nyle this , @KILNGUY or he'll get the big head


Too late!! smiley_whacko

Thanks Robert.
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Offline doc henderson

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there is a cycle throughout the day, like in a solar kiln.  at the high temp at mid-day, the high temp prob. has the RH very low, so too low to pull the water out, at least easily.  so I run the DH at night, when the temp is 70 and the humidity is 60%.  If the eve humidity is less than 40%, I do not turn it on.  I usually only run my dehumidifier in my container once a month to keep the humidity down.  more storage now than kiln.  I think even the Nyle shuts down at those temp, and tend to run at about 100.  to sterilize, it is usually at the end of drying, and the compressor is off.  It smells good in the container.  like wood, no musty smell.  mine is a Walmart one so not too expensive, but I work within the limitations of what I have.
timberking B 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor 12 volt tarp motor

Offline doc henderson

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most refrigerant gas, has to go through a phase change from liquid to gas.  that is why it is condensed to liquid (compressor) and then allowed to go through a expansion valve and into gas.  the heat density is less as a gas (temperature) so it pulls in heat (condenses water vapor) then compresses the heat containing gas back to liquid  (now really hot) and over a radiator.  ready to expand and be cold again.  there is a working range for that temp range for a particular gas and compressor set up.  so at a higher temp, the compressor may not be able to condense the gas to a liquid, and therefor can not condense the heat to create a gradient inside the kiln to get rid of the heat.  during a phase change, the temp stays the same, but lots of heat is gained or lost.  like when water boils, it gets to 212 and no higher in the water, the vapor is potentially hotter but disperses in the air.
timberking B 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor 12 volt tarp motor

Offline K-Guy

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What is the difference in a home dehumidifier and a DH kiln unit? Is it running different pressures or  .


Hi Don
Refrigerant type and pressures can both be different. The big one is that for safety reasons consumer products have thermal overloads that prevent it from operating at temps above 104F.
Nyle Kiln Sales & Service
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