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Thread: O.T. (slightly) - shop dehumidifier recharge?

  1. #1
    AeroncaChamp is offline Cast Iron
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    Default O.T. (slightly) - shop dehumidifier recharge?

    Anyone have any experience recharging portable dehumidifiers?

    I can't find a local repair guy that will touch a portable dehumidifier and it bugs the snot out of me that I'm expected to throw it away (actually have to pay money to get someone to take it off my hands here in the P.R of MA! #@$%) and spend $200-300 to buy another one that will last a mere 3-5 years.

    I'm pretty sure it's just a very slow leak. Compressors run, and the units both gradually (over a couple years) produced less and less water until they don't produce at all at the start of a season. One of them, an R22-based Whirlpool, was recharged during a recall repair, and worked for 3-4 years with the gradual failure.

    I can apparently buy an "environmentally safe" R22 "a" recharge kit, either with or without "leak stop". Has anyone had any success doing this? Any pitfalls to avoid? (I'm an engineer and shop rat... but no hands-on HVAC experience (yet))

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    BC21OSH is offline Cast Iron
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    Quote Originally Posted by AeroncaChamp View Post

    I can't find a local repair guy that will touch a portable dehumidifier and it bugs the snot out of me that I'm expected to throw it away (actually have to pay money to get someone to take it off my hands here in the P.R of MA! #@$%) and spend $200-300 to buy another one that will last a mere 3-5 years.
    Been there, done that. We have to pay at the local haz waste site for them to take them also. They probably have no refrigerant left, that's why they aren't working, and they have recyclable aluminum in the compressor.

    It's a shame with all the focus on "Green" that somebody doesn't come up with a better idea.

    I run two of them, one in the basement and one in the shop. Just replaced the one in the basement, got 5 years out of it, the one in the shop went in for warranty service last year, potential fire issue, but it doesn't seem to be pulling as much water as it did before. May be replacing it soon.

    Bernard

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    Ciszewski's Avatar
    Ciszewski is offline Hot Rolled
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    Hello AeroncaChamp
    My post will be no help to you, other than for moral support. I've been through that a few years ago. Took my unit to a repair shop, something like $90 just to put it on their bench + $90/hr. labour + parts. Didn't take long to realize that dehumidifiers, like most other consumer products made these days are disposable & are not designed to be repaired.

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    AeroncaChamp is offline Cast Iron
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    yeah, these are in my shop. I need to keep at least one running through the summer to keep the pipes from dripping condensation on things, and to keep my woodworking machine tables getting any rust haze.

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    henrya is offline Stainless
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    I bought a new one after the local authorized repair center told me they had a non-refundable $50.00 inspection fee to look at my old one. I guess they are disposable now-a-days.

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    MwTech Inc is offline Stainless
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    small systems like that are charged by weight. Even the hose length must be considered during charging.

    These days you can't just throw freon in and let er fly.

    At least no one in business that cares about staying in business(big brother)

    Do it yourself? -can't screw to much up unless you overcharge.

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    Bill D is offline Titanium
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    probably uses the newer refridgerant that runs at much higher pressures. the higher pressures cause it to leak out faster. No test ports so to refill you have to either braze on or use a saddle clamp valve. I doubt you will find any pressure charts for your machine since they are not designed to be worked on.
    To buy freon you have to have a license for most types.
    I got my license online, not too hard. learned nothing about ac just the laws about use, disposal.
    For cars they sell the little cans of freon AFAIK the appliance type formulas are only sold in the bigger tanks that cost several hundred dollars a tank. check ebay or craig's list to get price ideas.
    Bill D.

    PS: Ebay may have banned freon sales again

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    Depending on age (yours may be recent from your 3-5 year comment), you may find it better to replace.

    I had an old one in the shop, which I had had to replace the fan on long ago. Worked fine for 20 years or so. Finally the humidistat gave out, and I got tired of running it on a timed cycle.

    Replaced it with one from Sears of all places (before Sears closed down) and noticed that it drew a LOT less power, and did just as good or better job as the other ever had. I don't think the old one had leaked, it was the humidistat which was not available.

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    AeroncaChamp is offline Cast Iron
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    Update: First, thanks for commiseration and comments - esp MwTech... got me thinkin'...

    I figured the only cost was the kit - the dehumidifiers are junk anyway if they can't be recharged. So I bought a "Piercing Valve" and the R22a kit. R22a is "environmentally safe" and according to the MSDS contains "petroleum gases liquified"... "alkanes"... some mystery blend of methane, ethane, propane, and/or butane? Installed the piercing valve, checked pressure and found it to be zero. I fired up the unit, and slowly started introducing the R22a.

    Almost immediately, the evaporator coils near the top frosted up. Unit originally called for 12 oz. of R22, suction side 120 psi, high side 450 psi. I figure I'd put in maybe an oz or two of the 8 oz can. Low side pressure was ~30 psi. I continued to charge slowly, watching pressure, and expecting to use 5-6 oz (the can claims 1 oz of R22a is equivalent to 2.5 oz R22.) Well, pressure never rose above 65 psi and I'd put in probably 7 oz - a bit more than I'd intended to. The unit was producing water in a steady stream after a few minutes.

    So, 24 hours later, it's still running strong. So strong in fact that the water tank overflowed sometime during the day (the float must have been jammed when I put it back together) and I had mess to mop up. It's operating at about half the low side pressure that it was spec'd at with the R22 and it's not frosting up like it used to; I didn't put a piercing valve on the high side to monitor pressure, thinking that was a recipe for a future problem, so not sure the high side pressure. At half the pressure, I'm thinking that might last twice as long this time? maybe enough to give it a second life.

    I'll post another update in a week or so.

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    SteveF is offline Stainless
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    Good show.

    About six years ago my kitchen fridge wasn't getting cold enough to freeze anything so I put in a service call and the tech installed a saddle clamp on the low side and added freon. Problem returned about three years later and I topped it up again (added until it was between 5-8 PSI). Still working fine. May try this with a window AC unit that is getting weaker.

    Steve

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    Bob E is offline Cast Iron
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    Be sure to use the soapy water test to check for leaks.
    I salvaged 2 LG dehumidifiers by locating and soldering very small fracture leaks in the plumbing.
    Seems the copper they use isn't malleable enough for some of the bends.

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    henrya is offline Stainless
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    Excellent!
    Now I know why I have not thrown my old one out.
    I'm gonna give it a whirl.

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    Paolo_MD is offline Aluminum
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    Quote Originally Posted by AeroncaChamp View Post
    Update: First, thanks for commiseration and comments - esp MwTech... got me thinkin'...
    ...I'll post another update in a week or so.
    I've just found your thread looking for tips on how to fix the dehumidifier we have at Tuckahoe: For how long your dehumidifier kept working after the repair?

    Thanks!

    Paolo

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    TeachMePlease's Avatar
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    Quote Originally Posted by Paolo_MD View Post
    I've just found your thread looking for tips on how to fix the dehumidifier we have at Tuckahoe: For how long your dehumidifier kept working after the repair?

    Thanks!

    Paolo
    Dude's last activity on PM was 18 months ago. Doubt you'll get an answer.

  15. #15
    metlmunchr is offline Diamond
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    No way to judge how long your dehumidifier will last if you recharge it. It should last as long as it would have if it had never lost the charge. Main question is the size of the leak. Could be something really slow, or it could be a leak that allows the unit to lose all the gas in a couple hours or less. If possible, the leak should be repaired if it can be located.

    As others mentioned, repair costs make fixing a small dehumidifier a losing proposition if you have to take it to a repair shop. Same applies to small window air conditioners. Not much sense in spending $150 to repair a $110 device.

    One thing worth mentioning re the original poster's repair. The pressures he saw listed on the unit are the low and high side test pressures employed by the manufacturer in designing and testing the unit when it was made, similar to the pressure rating or test pressure listed on a compressed air tank. They're not the operating pressures, and the compressor would likely fail long before you could force enough refrigerant into the system to get it up to those pressures.

    The OP recharged his unit until the low side pressure was 65psi which is the correct pressure for a unit operating on R22. Actually, the textbook correct low side pressure is 67psi, but 65 would be within the accuracy of typical refrigeration gauges. The low side pressure determines the operating temperature of the evaporator coil which is what you're really trying to control. 65-67 psi would correspond to an evaporator temp of 38-40*F, which is what you want for dehumidification or air conditioning. Lower evap temps will cause icing on parts of the coil where the temp is at freezing or below.

    Also worth mentioning that the above pressures and their corresponding temps are applicable only to R22. For an older unit operating on R12, the pressure would be substantially lower to achieve the same evaporator temperature, while a newer one operating on R410A would run at a substantially higher low side pressure.

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    AeroncaChamp is offline Cast Iron
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    Hey, OP here... reduced to lurker of late

    So I ended up recharging two of the three units. The no-name unit is still working, but at the start of this season was icing up pretty badly. It always did ice up when temps in the shop are at the low end, so at first thought it was just the long cold spring, but it's still doing it.

    The whirlpool unit took a charge and worked well for several weeks, then failed - with a muffled "pop". Perhaps too much pressure when I recharged?

    I used R22A - a claimed environmentally safe substitute for R22. The paperwork that came with it said to use a lot less of it by weight. I recall a ratio of about 1:3 or 1:4. (don't quote me on that.) I split a can of leak-stop between the two units.

    so I'm 1-for-2. Not a bad batting average, but I can see why the shops won't touch them. Pity no one makes (or I haven't found yet) a higher quality unit.

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    neilho is offline Hot Rolled
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    Quote Originally Posted by AeroncaChamp View Post
    ..... Pity no one makes (or I haven't found yet) a higher quality unit.
    I haven't justified buying a good one yet, but a "low temperature dehumidifier" search of the site turns up a few interesting threads.

    Here's a review page of several units good to about 40 deg F, none of them cheap. Basement Dehumidifiers | AllergyBuyersClub

    And a reportedly higher quality unit ...

    Amazon.com: Santa Fe Compact 2 Whole House Dehumidifier (4033600): Home & Kitchen

    I've been getting by with older yardsale units, substituting 4 quiet muffin fans for the single roaring one they came with. Keeping an eye out for a better one, though. I'm down to my last spare...

    Neil

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