Teach me about dehumidifiers

[Hobby_Man22]

Looking to buy one of those commercial grade ones you see for like $1200 that take out like 100 pints per day.

Something like this


https://www.amazon.com/dp/B0711CGWXX/?tag=atomicindus08-20

 

[Hobby_Man22]

Or should I just spend $100 bucks on a household one and buy a new one every year. I heard if you use them in dusty evironments that they don't last long. I would think a commercial unit would have a filter you can change out. Are these things loud? Will this work in a wood shop? I try and keep the dust in the air to a minimum by using a dust collector when I can.

 

[Mark_17]

Can you give some more details on where you are using it and what you are expecting?

The one you linked is for 7200 sq ft. Household ones are usually ~3000 sq ft or less. They are hard to compare.

 

[Hobby_Man22]

That was just an example. It's for a steel building 30x50x12 Two bay doors and one side pedestrian door.

 

[yeldogt]

You can call the manufacturer ...

Most of the consumer units are even more energy hogs than the commercial ones. Check out the pints removed per KW.

Also -- take note of conditioning. It's often not much more to condition with AC to remove the humidity in the summer. Most times you need the dehumidifier when it the shoulder season or when it's just crazy humid and you are opening the doors more.

 

[Showkey]

DO NOT assume because it cost $1500-$3000 they will last any longer than the residential units. This has come up many times prior. No real conclusions either way other than they are all high maintenance and suspect life expectancy.

Yes some are better and get great reviews but Read the reviews on these high dollar units:

“I had an older 1750A unit that lasted 3 years, and lost refrigerant charge. Aprilaire replaced that unit under warranty "free" with an 1850 unit. The 1850 lasted just under 5 years, and has lost it's refrigerant charge now. There are NO refrigerant charge ports on these units When it works, it works well and is eff…”

“amps ftp://ftp.aprilaire.com/Fulfillment/Dehumidifiers/Dehumid-1850-series-spec-sheet.pdf My suggestion is to not buy one. They last about 1 1/2 years and parts are either not available or very expensive. I had 3 each break 5 years. Consider Ultra aire”


If your seasonal use $150-$300 units often come with 3 year warranty. I am more than happy at $50-$100 per year ........I warranty one last year so the 3 years starts over.

$2100 at 7 years is $300/year.

If the building is not well sealed, low air exchange and insulated any unit will cost $$$ to operate and effectiveness will suffer.

 

[Vintage Veloce]

Years ago I lived near the beach and it was often foggy and you could smell the salt air. I noticed stuff starting to rust in the garage, so I installed two sears dehumidifiers piped to drain outside.
I wasn't ever sure it helped much. Probably because the garage was pretty leaky to outside air.
My point is, if you haven't already, maybe check with others in your area to find a solution that has already proved to work. And make sure your garage is air tight.

 

[Hobby_Man22]

My dad always had one on his boat and i think they quit working every two or three years.

 

[Jackfre]

Before I did the de-hu unit I’d throw that money at say the cheapest 18-24k btu mini-split and run it on de-he mode. It will give you redundancy and solve much of your oversizing issue with your central system.

 

[930dreamer]

X2 on some type of shop AC unit as you will get two birds with one stone, as long as the shop is insulated.

 

[Hobby_Man22]

Before I did the de-hu unit I’d throw that money at say the cheapest 18-24k btu mini-split and run it on de-he mode. It will give you redundancy and solve much of your oversizing issue with your central system.

I don't understand why everyone thinks it's oversized. Oversized means it reaches target temp too quickly. That's not my problem.

 

[Jackfre]

No oversized means that the unit is not getting the latent heat, that is humidity, before it get the sensible, that is temp. As a result I think that as things heat up this summer you will find the space cold and clammy, to a degree at least. Mini-splits de-humidify really well. Dehumidifiers are expensive to run and in my experience do not last. By this time you spend enough money on a commercial unit you are most of the way to a mini-split system which will do a better job. Check some of the specs on dehu’s vs mini-splits for moisture removal.

 

[Hobby_Man22]

No oversized means that the unit is not getting the latent heat, that is humidity, before it get the sensible, that is temp. As a result I think that as things heat up this summer you will find the space cold and clammy, to a degree at least. Mini-splits de-humidify really well. Dehumidifiers are expensive to run and in my experience do not last. By this time you spend enough money on a commercial unit you are most of the way to a mini-split system which will do a better job. Check some of the specs on dehu’s vs mini-splits for moisture removal.

Oh. Well ibthinknits just the time of year right now. The temp outside stays around 65-75 degrees from now until the end of April. Even my house is sitting at 72 percent humidity the last few days because the a.c. just isn't running much.

 

[Firebrick43]

I agree with Jackfre on the mini split. You would be paying for the electricity anyway as Dehumidifiers are basically full system ac units that move heat a few inches and dump it back into the room instead of outside.

 

[Showkey]

So why is spending $3k on mini split going to fix this temporary humidity issue ??????

If the indoor temperature is in your desired range the full AC and mini split are not going to run or run very little.

Another month it’s likely to be hotter than hell and AC will running day and night.

If we are looking to a temporary cure........run the heat and warm those cold steel rafters above the dew point ........problem solved. Or just wait for the weather to change. In the upper Midwest out concrete floors will be sweating real soon as a comparison.

A $150-$200 dehumidifier will use 500-700 watts to run........no big deal in the grand scheme..........plus it temporary.

 

[Firebrick43]

who said it had to be a 3k mini split?

small ones are much cheaper

 

[TonyG109]

I have a pole building with the exact same dimensions as your building. Before I installed a mini-split I used a 70 pint big box dehumidifier for about a year and a half. It worked great! Rust on bare steel was a thing of the past. When you first walked in on a hot day, it almost felt like it was air conditioned!

Now, the building is very tight with very few air leaks which, I'm sure, was a factor in the success of using a dehumidifier. I set the unit at about 55% humidity and it would actually cycle off at times. A drain hose routed outside was used to get rid of the water.

As far as reliability of the units, this particular unit was used in a college dorm for a year prior to being used in the garage. It has since been moved to my basement and has been going strong for a total of 4 or 5 years. I also have two other units that have many years on them and still work. One has been in a crawlspace for over 10 years and still works.

 

[Hobby_Man22]

Tony I bought a 70 pint unit for like $250 and instead of it being 83 percent humidity in the shop it stays around 60 now just like the house. What a difference too! Before it just didn't feel right. Either muggy or just damp even though it was a reasonable temp.

 

[Hobby_Man22]

It seems a bit cold for this time of year in Houston honestly.

 

[southalabama]

Our family lake house is closed most of the year. We began having mold issues. Now we run ceiling fans and a Wally World dehumidifier. My dad never buys an extended warranty except on the dehumidifiers. He’s had them replaced a couple times.

 

[Hobby_Man22]

I wonder why they don't last very long. isn't it just a compressor same as a refridgerator or something? Those last 20 years.

 

[Firebrick43]

its actually more like an air conditioner, just the heat is taken out of the air, condensing the water out and the heat allowed to reenter the same air. You use just as much electricity as an equivalent sized unit but none of the cooling benefits. you actually end up heating the air due to the electricity they motor is using.

 

[Bert_]

I've got a dehumidifier that's probably 30 years old in my basement. It's old enough to be brown with fake woodgrain.

New ones don't last as long but neither do most appliances.

 

[metlmunchr]

You can add a SPDT toggle switch to the control wiring of a split heat pump and use it as a dehumidifier. Center post out to the aux heat relay. One end fed by a branch off the control wire that enables cooling and the other fed by the wire that normally goes to the aux heat relay.

You end up with a unit that will cool the air to remove moisture and then reheat it before it is discharged with the switch in one position and normal heating and cooling operation in the other position.

Not a way to save energy, but it will give a lot of dehumidification capacity without cooling the space excessively during times when humidity is high but outdoor temps aren't sufficient to put much load on the system.

This only works with units with draw thru cooling coils and the aux heat on the discharge end of the air handler.

FWIW, cooling the air to uncomfortable levels to remove humidity and then reheating it is common practice in many industrial and institutional situations. This isn't done with heat pumps, but the net result is the same.

 

[TonyG109]

Tony I bought a 70 pint unit for like $250 and instead of it being 83 percent humidity in the shop it stays around 60 now just like the house. What a difference too! Before it just didn't feel right. Either muggy or just damp even though it was a reasonable temp.

Glad to hear it's working! Simply controlling the humidity solves so many issues, whether it's in the garage or the house.

 

[fitter30]

Commercial and the better crawl space dehumidifiers have a A.H.A.M. rating for pints per day. Aham rates there rating at 60% 80°. Box store 90% 80°. Aham rated usually have a better filter than box store. I'm using a honeywell crawl space dehumidifier have been using it for 10 years with no problems. Any dehumidifier loses capacity as the temp goes down with Aham manufacturers have that info. Mini splits don't like dirt their indoor coils like outdoor are enhanced little slits in the fins that make them hard to clean.

 

[toyotadriver]

I needed a dehumidifier for the basement in my house. It was a new house so the concrete was giving off moisture for awhile. Only needed to be run in the spring especially and then some in the summer and early fall. I bought a Frigidaire 70pint from Lowes. Worked great for a year. At the end of the second year I had it, it stopped working. Had it warrantied at Lowes but they didn't have the Frigidaire ones any more so they gave me some other brand. That one didn't even last a year. Ended up getting one from Menards. Not sure what the brand was and it was the cheapest I could find but it also had a 3 or 5 year warranty..can't remember which. I decided if they are going to die quickly, I might as well buy a cheap one. I figured it would die a quick death like the other two but it has outlasted both....think it's 3 years old now. Still working fine.

 

[Jeepster04]

Ive bought two 'used' units from amazon warehouse. I think they were around $80 shipped, which blows my mind. Cant remember the brand.

One is nearing 2 years old, another is almost a year old. They work perfect and keep the humidity at whatever I set them too. Its actually too low in my house but Im too lazy to crawl into my crawl space and raise it. Its set to 55% and the humidity in my house stays in the 40% range, even when its raining outside and the air isn't on.

 

[TonyG109]

Well, I think I jinxed myself! One of the humidifiers that has worked for 4 or 5 years just bit the dust. Looking back, that one probably was actually about 7 years old. It was a Whirlpool Gold. I replaced it with another Whirlpool because it was the only brand quickly available at the time.

I think brand reliability is a bit of hit or miss. Some brands seem to have better overall reliability ratings, but the individual unit is a **** shoot. The decade + old unit in my crawlspace is still working! (I hope I didn't just jinx myself again... )

 

[Jim greengo]

I needed a dehumidifier for the basement in my house. It was a new house so the concrete was giving off moisture for awhile. Only needed to be run in the spring especially and then some in the summer and early fall. I bought a Frigidaire 70pint from Lowes. Worked great for a year. At the end of the second year I had it, it stopped working. Had it warrantied at Lowes but they didn't have the Frigidaire ones any more so they gave me some other brand. That one didn't even last a year. Ended up getting one from Menards. Not sure what the brand was and it was the cheapest I could find but it also had a 3 or 5 year warranty..can't remember which. I decided if they are going to die quickly, I might as well buy a cheap one. I figured it would die a quick death like the other two but it has outlasted both....think it's 3 years old now. Still working fine.

Do you have ductwork in the basement?

 

[toyotadriver]

Do you have ductwork in the basement?

Yes. Ducts and returns.

As the years have gone by, the basement has dried out so the only time we run the dehumidifier any more is a little in the spring and sometimes a little in the fall. If we get a lot of rain and real humid temps we sometimes run it mid summer but that’s pretty rare.