Coping: Dehumidifier Adventures

As readers know, the office-shop of UrbanSurvival is a glorious (verging on palatial) place:  Tools galore, plenty of electronics for the Extra Class ham radio op in you, or whatever turns your crank.  Pass the plasma cutter and sample three different “on-ramps” to the Internet.

With summer here, though, and not figuring it to be worth the expense of fully-insulating the shop (mostly 2-4 studs covered with clear polycarbonate panels to let in lots of natural light), I went looking for solutions that would fit within the “energy budget” of our solar power system.  Which, if you’ve forgotten is 400 Amp-hours of battery and 110/220 volt stacked Outback Power grid-interactive inverters driven by 3.5 kW of panels and a pair of Flex-60 MPTP charge controllers.

I came up with basically five ways to cool the shop.  Some practical, some not so much.  First would be to run A/C and go with a somewhat more efficient inverter-DC unit.  In old-style air conditioners, the compressor is cycled on and off for cooling.  But, with the new technology, the compressor, fans, and the whole shooting match runs continuously…just not as fast.  Avoiding the high-current stop-start, turns out, saves a lot of energy.  But, like any new tech, it’s more money…

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A second option would be a “swamp cooler” – not to be confused with rain in the nation’s capitol.

The way these work is water is drizzled water over a “media” (think gunny sacks) pumped by a small aquarium pump while and a big herking fan blows air through it.  Cooling is the result of the evaporating water soaking up heat.

It all sounds good because it can generate cooling at a fraction of the cost of conventional (compressor AC).  It only works, though, with relative humidity under 60%.  A bone-dry desert is better, though.

I had only been in one place in recent years in the summer, where this kind of cooling was used.  That was a hardware store in Frankston, Texas.

So, I called them up to see how well their unit worked.  Always check with people who have first-hand experience, right? Around here, the humidity levels are all over the place.  With the peak heat of the day, they may drop to 40 percent.  But in the mornings, when it’s gotten down to 70 overnight and there is heavy dew, you may see 100 percent.

Not in a shop,” someone answering the phone began.  We had a nice chat about how the cool, but very moist air, works for some thing, but how tools doesn’t last long.  Things rust…quickly. Blink quick.

Then I penciled out a couple of “exotic solutions.”  One – which works well, I hear, is to bury as much 12 to 20 inch diameter plastic pipe as you can afford down 10-feet, or deeper.  Average ground temps run in the mid 60’s here, so simple and cheap!

You put an intake pipe up several feet in the air (keeps critters out) at the far end, perhaps 150 feet of pipe away, filtering filters (another use for women’s nylons, last seen in 2003).  Then power the whole shebang with a 12 or 24 volt DC fan to suck cool air into the building..

Since we have an old HydraJet water well rig, I could do the same thing by building-up long 4-inch copper tubing coils and dropping two or three of them down to the ground water level, which is about 70 feet under the office depending on time of year.

At the other end, a small repurposed car radiator and a 24 volt water pump would circulate the water from the heat sink underground to the radiator in the office with an air fan on the office side.  Scaled up to the size of the shop, though, this begins to look like a plumber’s wet dream and a PVC pipe rep’s retirement package. Nice dream for a radiator shop,. too.

Then we come to thermal cooling towers, one of the first low energy technologies, which comes by way of certain African villages where they form cool community living spaces.

The idea of a thermal cooling tower is you build an upside down  (flared end of a trumpet down) looking shelter out of reeds and wood.  As the sun heat the tower, up goes the air which naturally rises when warm.  This, creates a vacuum which pulls cool replacement air in around the base.

On a 90+ day, 5-10 miles an hour of updraft is dandy!

Sadly, there’s no way to accomplish this one, since there are too many tall pines around the office.  It would take 20-40 trees being removed and that’s not economic.

Understand that as a tree farm operator, there are only two ways to approach trees:  Either hire specialists (the last one charged $800 to cut down one tree) or get enough trees lined up that a local logging outfit could bring in a crew and equipment for a week and move out lots of trees.  In the latter cas,, you make a fair bit on the tree sale, but the land is left a mess.

Way too much hassle just to make the shop a little more comfortable.

So…;the winner is?

Pardon the long link here: Portable Dehumidifier by hOmeLabs, 9 Gallon (70 Pint) Energy Star Safe Mid Size for Basements Large Rooms up to 4000 Sq Ft with Fan Wheels and Drain Hose Outlet to Remove Odor and Allergens…

Don’t buy the unit, just yet.

The Amazon/manufacturer specs are misleading.

Let me tell you a story of how “Marketing People are Idiots” and show you how the specs are wrong on the unit I received…

It arrived Tuesday, courtesy of the USPS.  I left a hand truck out for our Post Office carrier (Jason) so he could just plop it out of his ride’s trunk and onto the hand truck, so as not to break a sweat.  By the time it was unwrapped and set up (there’s a plastic part in the water tank, so don’t forget to remove it…like someone I know didn’t!) it was 4 PM.

I figured it would run it overnight and might suck a gallon of water out.

Imagine my shock when, at 5 AM the next day, I came out to the shop and found it was full, already.

Could it pull 9 gallons in less than 12 hours?

After dumping the water, an alarm bell went off:  The Amazon write-updid say this was a 70-pint capacity unit.

It’s not.  Er…it is, but depending on how you define capacity.

Remember the old saying “Pint’s a pound the World-around?”  8 pounds per gallon?

Well, sleepy though I was, the weight of the water taken out of the unit was far less than 72 pounds if 9 of those 8 pound gallons were captured.. It felt like 10-15 pounds.  I’m buff for 69, but are you kidding me?

After waiting for the unit to suck another load of water out of the shop air, I waited for it to turn off when full.

Since I’d started the unit at 5 AM, and sure enough, around 10:15 AM, it was full for a second time.

Since my shop is called Olde Man Labs where I work on real physics questions (see my books on Amazon), here’s my set up for testing:

I weighed the full water tank.  Here’s what the digital number-twanger reported:

Oh-oh.  14-pounds 10-ounces?  The very tops it could be holding would be (14+(10/16) would be 14.625 pints. or 1.828125 gallons.

But it’s not really even that much.  We still have to back-out the weight of the empty water bin in the unit.

I didn’t thoroughly dry it, but it weighs how much?

So we take the total (14.625 pounds) of water plus the water bin.  Then we back out 2.85 pounds (which is the water bin weight empty (but not dried) and we get a REAL water capacity of 11.775 pounds.


There are other ways to estimate the tank’s real size.  Measure it.  Length times height times width.

Now divide:

And how many cubic inches are there is ONE gallon of water?


Say your measurements multiply to 500

500 divided by 231 means a 2.16 gallon capacity based on volume.

With both a weight and volume check, the capacity specs claimed in the add are useless.

That said, now you can go ahead and buy the unit.  We give it an initial four stars.

It sucks a LOT of water out of the air.  But will it work on 4,000 square feet of home?  Let’s just say when  one specification is obviously wrong, the other ones ought to be questioned.

What may have happened is the “70-pint capacity” could be based on how much water it MIGHT suck out of the air in a 24-hour period under ideal lab conditions. Even here, color me skeptical.  BUT it is pulling close to 4-gallons out of the Old Man Labs shop….and that’s why it’s OK to buy.

I doubt any of the dehumidifiers on the market will pass a real performance and measurement test like this.  Get the hose. Unless you like to water your lawn with a bucket.

Now to the prepping reason TO BUY the unit..


There really is an important prepping aspect to it which we do think about at  Lots..

I have not tested the water quality coming off the unit, but if I lived in another hot, humid state, like Florida, it would be simple to put together a good emergency water source using the unit.

Background:  When we were offshore sailing in the early 2000’s, we figured on a tight water ration, people on the boat could get by with one gallon per day, per person.  Two gallons would be generous.

If the unit puts out, four gallons per day, then two people might remain hydrated on its output.

I’d wash the bin to remove parting compound from manufacturing.  Run it through a LifeStraw or a lightweight reverse osmosis system, and now you have a dandy back-up water source, as long as you have power.  Minimal for four, workable for two.

I won’t be sending my unit back…it’s a keeper, at least so far.  But somewhere, back in marketing pre-history, a zealous marketer used the “70 pint” nomenclature and it seems to have gone viral.

Don’t buy the unit based on the specs…there’s simply not room for 70 pints.  Try 11.78 pints.

Don’t buy this unit for the specs.  Buy it for what it really does.

For us, for now, it’s OK.  We’d like to see Amazon do some “spec checking” though.

Write when you get rich,

author avatar
George Ure
Amazon Author Page: UrbanSurvival Bio:

30 thoughts on “Coping: Dehumidifier Adventures”

  1. Start with #1: insulation.
    R-24 in walls.
    R-45 in ceiling.

    Hey, and the neighbors and wife will appreciate the added quiet. :)

    • I would use closed cell foam insulation only, good for weather exposure and placed on the outside of the plastic walls. It could be removed for winter. I put 2″ foam in all of the windows I don’t use. Curtains on the inside make things look normal and the place is much cooler – especially for western exposures.

  2. Kinda has to do with your relative humidity at the time too. Another factor to consider.

  3. maybe the spec was maximum amount of water that could be removed in 24 hrs from a 100% humidity air (at a certain unspecified temperature). Actually not a bad spec, really relates to compressor size and fan speed. Sort like a BTU rating. But downside is that dehumidifier actually makes the air in the room hotter. TANSTAFL. What you are trading off is, can you make the real feel temperature go down faster than the actual temperature goes up.

  4. Hi George,

    I’ve been using dehumidifiers all my life in my basements, and your thoughts on the one you bought missed one little item in the ‘capacity’ description.

    I have mine plummed with a hose connected to the collection tank that drains it (constantly) to my sump pump.

    The ‘capacity’ of 70 pints (9 gallons) is a rating over a 24 hour period, not the catch pan’s capacity. It is an accurate description as they’ve used this nomenclature of all dehumidifiers as a measure of how much moisture they are capable of extracting from the air over time.

    Think of the rating as ‘GPD’ (Gallons Per Day) as a standard measure like we think of speed as MPH.

    Another FYI, if you don’t want the water to use, run a drain off the tank at the provided drain fitting. The volume is low/slow, and even if you had a concrette floor (like a basement) and don’t have a convienient drain, you can drill a 1/2″ hole through it far enough to reach dirt, and drain into it as it will easily be absorbed into the ground.

    Hope this clears it up a bit!

    Thanks for all you do for us!


  5. Just be aware that the collection tank tends to develop a lot of mold. Be sure to treat/filter the condensate appropriately if using for potable water. YMMV
    James Johnson, ex-nuke

    • Install a UV-C sterilizing light on the tank and shield it from your eyes. It will keep the water clean and then just run it through a Big Burkey filter.

      • you should see my filtration system LOL.. My wife thinks I went overboard.. even put one on a hand cart so the rain water coming off the roof can be used.. what is funny is five minutes of a steady rain will fill a five hundred gallon reservoir tank.

  6. George,
    It would be nice to know the energy consumption of the dehumidifier, as well. I would like to run this on my solar system to make water with excess power, as I am not grid-connected and just throw away the excess power I capture.

  7. I’ve been using mine as a source of distilled water for battery top off. It is a still, right? Not so hot for drinking without some minerals added though!

  8. The Lifestraw is a sucking device (straw – get it?). It can not be used to filter a bucket of water. A Lifestraw Family or Lifestraw Mission is a different animal. Makes me wonder if you have ever used a Lifestraw yourself. Pretty nifty for hiking or camping when your water source is a stream.

    • LOL, yeah…I figured on sticking the LifeStraw into the unit’s water bin…guess that wasn’t clear…but yep, it would work….

  9. Like comedian Steven Wright once said: “I bought a humidifier AND a DEhumidifier; they can fight it out!

  10. I find that a $120, 600 watt AC unit can do a lot of cooling and dehumidifying. Of course the modern ones take the condensate and splash it on the coils to increase efficiency. But our central unit produces many gallons a day, which we irrigate with. Is there an advantage to dehumidifiers over AC?


      awesome unit..same price as a regular air system and more efficient less energy..

      Many grocery stores have misted their produce to keep them cool.. for years.. well misting your conditioner coil does the same thing speeds up the heat transference.. I got one of these a few years ago.. wow.. knocked two thirds of the electric bill for the air conditioner right away..

      you can do the same thing with a patio I do it around my vegitables.. set up water lines and put misting nozzles in it..

      • another way to condition air is by using vortex air compression once the compressed air expands it cools.. by compressing air through a small vortex unit or series of compression units you drop the air temp by expansion after it leaves.. using a box fan and a compression unit setup you now have an effective way to cool your air with a fan operated air conditioner. simple to use simple to make and effective ..

  11. My husband has two going in his shop all the time. They do remove a lot of humidity from the air and his tools no longer rust (we are on the gulf coast) but these things put out a lot of heat. It’s almost unbearable to go into the shop, which is insulated, during the summer months.

    • I use an auto paste wax to polish my tools… it keeps them from rusting during the humid days..

    • the other think I keep in my tool box to keep rust from forming is camphor tablet.. I put it in a medicine bottle drill a couple holes in it and just toss her in..

  12. With regard to using earth temps for heating and cooling. I have a friend in your area that is a retired architect that has used earth temp heating and cooling in construction. If memory serves me correctly the temp at 6 ft. of depth in your area is about 72 or 76 degree F. year round. 4 inch piping spaced at 2 feet works if using water as a medium to transfer temperature. Larger if using air. The diameter and length of piping will depend on the cubic feet of space to be heated/cooled. Somewhere I have the stats filed for this. However, if you ever get serious I may be able to put you in touch with my friend who is about 30 minutes from you.

    • exactly.. years ago I was asked to submit my idea on a house.. I called it an envelope.. where you let the sun cool it and heat it using the earth as the source.. this actually wasn’t my idea originally I got the idea from some buildings in turkey that are over ten thousand years old.. the Romans also used the same construction idea to heat and cool their villa’s.. they used a heat chimney to do the work though.

  13. dehumidifier a perfect example of an air well.( of course this one uses electricity where one could be made out of whatever like a spiders web) . now .. if you hooked a small submersible pump with a float switch to pump the water to a holding tank with a good filtration system you would have plenty of clean crisp cold water for the shop ready to make coffee.Or you could just pump it to a holding tank to use on your garden. ( which is what I do )…

    • Oh the coolerado is a hybrid swamp cooler using air in such a way that the moisture stays outside. This also can be used as a dehumidifier.
      I visited with the gentlemen that invented this process used. The energy used is six hundred watts max compared to up to ten thousand for a conventional air

  14. Hmm.. Why not make a solar air conditioner! Let the sweltering heat of the outback cool your shop for you. you have good southern exposures. Its relatively easy to do Condense the sun on your coolant tank.( I am prone to use vodka as the refrigerant.) Then run your vapor line to a coil with a water bath then down to your expansion coils. A fan behind that to blow the cool air into the shop. the cool coils condense the humidity which then can be pumped and filtered for ice cubes or consumption or any other. the vapor condenses it flows back to the coolant tank to repeat the cycle.. Similar to a still but in a closed loop. The expansion tank or coil can get quite frosty like minuus.
    Just a thought easy to build. Simple design..

    • I made the mistake of showing the grandkids how to melt stone using the sun.. bad mistake really bad mistake.. they were melting everything under the sun.. vaporizing gummy bears takes only seconds to do LOL.melting cans and everything in between… I was afraid they were going to burn the house down.. after that I decided to just show them how to use the power of the sun to freeze things instead.. LOL a lot easier and I don’t have to worry about a burned down house LOL..heck you have a shop full of tools and the ingenuity it would’t take long with just some old junk to put something together.. my plan is a solar grill this summer as one of my projects.. the solar oven caught me off guard.. I knew it would work I just didn’t think it would get as hot as fast as it did and burned my fingers grabbing the pot LOL..

        Darn they make one.. although I am not sure what ther are using the compressor for.. the vacuum tube used to vaporate the coolant which flows into a coil where it’s cooled by the fan with a return line for drop off moisture then to the expansion coil mounted on the wall in the house etc. with a fan to distribute the cool air and drain pan for the condensation.. the coolant should not need a compressor to send it back to the solar evaporator since as the solar chamber cools the refrigerant is cycled back normally through expansion contraction.

  15. George, I was born and raised in the hot, humid South and much of it before A/C. Here’s my suggestions: 1. Build a cupola on your shop’s roof; 2. Install a high-cpf attic fan below the cupola – if you need 220v then put an automatic shunt to serve either the fan or the welder as in use; 3. Install sun screen fabric on the inside west/south walls with motorized raise/lower controls with timer or Amazon device; 4. place vents at floor level on north side or duct out to beneath a shade tree.

    Attic fans are wonderful and farmers used to vent their barns with cupolas. Materials available from Amazon. Might work for a fairly low cost solution?

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