dehumidifier for the shop?

[Hobby_Man22]

Anyone use one of these or is it a waste of money? Can you connect a hose to it so you can just let it drain outside? I'm talking about a good one that's like 1500 bucks. Not one you buy from walmart for $150 I do have an hvac system, but times like this where it's already 70 degress outside it can get up to 80 percent humidity in the shop.

 

[WisJim]

How big is the shop? What kind of insulation? How many doors and how well do they seal when closed? If the building isn't tight and insulated nothing is going to cure the problem.

 

[theoldwizard1]

If you have a concrete floor with no vapor barrier under it, you will be fighting a loosing battle. You won;t be able to pay the operational cost to get the humidity down low enough during certain ambient conditions.

 

[iced98lx]

Depending on the conditions it may be nearly impossible to get it to a level you want as noted by @theoldwizard1 but nothing is more frustrating than rusty tools.

I have used the UltraAire brand (this one: https://www.sylvane.com/ultra-aire-70h-dehumidifier.html specifically) in the past in a house that had constant humidity issues (regardless of the outdoor humidity, assumed to be due to foundation location and water table...) and it kept things in check but ran a lot. Cost to run was high but worth it in that case, may or may not be in your case depending on the value it represents as far as things being destroyed.

 

[Hobby_Man22]

Depending on the conditions it may be nearly impossible to get it to a level you want as noted by @theoldwizard1 but nothing is more frustrating than rusty tools.

I have used the UltraAire brand (this one: https://www.sylvane.com/ultra-aire-70h-dehumidifier.html specifically) in the past in a house that had constant humidity issues (regardless of the outdoor humidity, assumed to be due to foundation location and water table...) and it kept things in check but ran a lot. Cost to run was high but worth it in that case, may or may not be in your case depending on the value it represents as far as things being destroyed.

The air conditioner will get down to 60 percent. Except for the times when it doesn't run due to it already being 73 outside.

 

[Showkey]

This vapor barrier under the slab is total nonsense as far as controlling humidity in a shop or basement. Air exchange and building seal and insulation is far more important.

Most basements in the north have no vapor barrier under the slab. There is no trouble running a dehumidifier and achieve 40-50% relative humidity at 60-70*. With or without AC running. Same for typical shop or garage.

The only wild card would be if the building was built on spring or swamp land.......then all bets are off.

 

[jjrbus]

I am in Florida and have constant high humidity. I looked into the high end dehumidifiers. Things changed and now run the mini splits in dry mode when needed. Seeing 50% humidity in my house is very rare unless it is dry outside.

 

[mike93lx]

This vapor barrier under the slab is total nonsense as far as controlling humidity in a shop or basement. Air exchange and building seal and insulation is far more important.

Most basements in the north have no vapor barrier under the slab. There is no trouble running a dehumidifier and achieve 40-50% relative humidity at 60-70*. With or without AC running. Same for typical shop or garage.

The only wild card would be if the building was built on spring or swamp land.......then all bets are off.

This. I guarantee there is no vapor barrier under my 50 year old basement and my two dehumidifiers easily keep my garage and basement at 50% all year round. That includes parking wet or snowy cars in the garage

 

[SweetD]

This. I guarantee there is no vapor barrier under my 50 year old basement and my two dehumidifiers easily keep my garage and basement at 50% all year round. That includes parking wet or snowy cars in the garage

Mike, what brand/type of dehu's do you run?

 

[Hobby_Man22]

I saw some black plastic in a few areas at the bottom of the slab sticking out. Is that vapor barrier or something else?

 

[mike93lx]

Mike, what brand/type of dehu's do you run?

Midea. Bought on Amazon. They have been great so far. I have the medium size and the smallest. If I was buying again I wouldn't get the smallest again... The bucket is too small and the fan is louder

 

[TractorJeff]

I saw some black plastic in a few areas at the bottom of the slab sticking out. Is that vapor barrier or something else?

I would "GUESS" Yes?

 

[iced98lx]

The air conditioner will get down to 60 percent. Except for the times when it doesn't run due to it already being 73 outside.

Then a unit like I linked (sized properly, obviously) should work to cut it down to where you want it, just remember you're adding heat back into the room with it running.

 

[drboom]

I've run a dehumidifier in my garage/shop for the last couple of years (NH). One unexpected benefit is that the bugs and spiders have almost gone away in the garage. I used to vacuum up lots of dead bugs around the corners and entrances every couple of months due to effective spiders and pest control but, since I started using a dehumidifier, they are almost completely gone.

 

[mobetta]

That could just be neonicotinoids - how much roundup do you use?

 

[Showkey]

Then a unit like I linked (sized properly, obviously) should work to cut it down to where you want it, just remember you're adding heat back into the room with it running.

That maybe slightly true if your were running the dehumidifier in closet. The amount of heat a dehumidifier produces is small to almost not measurable .......especially since the cooling ( evaporator coil (cold part) is right next the warm part the condenser coil then the fan blows over the compressor and both coils. So the heat gain would be the compressor getting warm.

Example running a dehumidifier in garage or basement you will see no real change in the temperature.

 

[SweetD]

Midea. Bought on Amazon. They have been great so far. I have the medium size and the smallest. If I was buying again I wouldn't get the smallest again... The bucket is too small and the fan is louder

Thanks!

 

[mepstein]

I buy them at Costco so when they go bad, I just return for a new one. I always get the one with a pump so it empties it’s self.

 

[Jeepster04]

I buy them at Costco so when they go bad, I just return for a new one. I always get the one with a pump so it empties it’s self.

What kinda warranty do they have? I just bought a Midea from amazon but may cancel it.

How much are they at costco with the pump?

Ive had a dehumidifier in my garage for around 8 years and will always have one. It doesnt really help with rust if everything in the garage is cold. Soon as you open the door on a humid day, it will condense on everything. Having A/C in the garage can actually make it worse. I dont have A/C so its typically the same temp in my garage as it is outside in the summer. Sometimes when we have have big temp swings I'll still see some condensation on stuff when I open my garage door.

 

[Showkey]

What kinda warranty do they have? I just bought a Midea from amazon but may cancel it.

How much are they at costco with the pump?

Ive had a dehumidifier in my garage for around 8 years and will always have one. It doesnt really help with rust if everything in the garage is cold. Soon as you open the door on a humid day, it will condense on everything. Having A/C in the garage can actually make it worse. I dont have A/C so its typically the same temp in my garage as it is outside in the summer. Sometimes when we have have big temp swings I'll still see some condensation on stuff when I open my garage door.

You do mention your location ?
Once you commit to “conditioning” the shop/garage space opening the doors do a complete air exchange........so all the time and energy in the conditioning of the air is lost.
Large temperature swings in the outside temperatures make the inside condensation issue worse.......especially in spring when the inside garage is cool/cold and the warm moist spring air it’s the cold. There is not real efficient way stopping this .......other than warming and drying garage/shop air and contents or keep the doors closed.

It’s the same as the iced tea glass on hot humid day causing sweating or condensation which we have mentioned on the forum many times.......especially on the cold concrete floor.

 

[Max]

I live in the hot and humid south. My shop is a 2 car garage that is part of the “daylight basement” of the house. As such it has the house above it as a heat shield, so the major issue is humidity and not heat. I got tired of the cheap dehumidifiers lasting six months, so I finally bought an AprilAire 1830. I’ve only had it a year, but so far it’s great. it has a 5 year parts warranty and it has no issue keeping my shop less than 50% all of the time.

 

[iced98lx]

That maybe slightly true if your were running the dehumidifier in closet. The amount of heat a dehumidifier produces is small to almost not measurable .......especially since the cooling ( evaporator coil (cold part) is right next the warm part the condenser coil then the fan blows over the compressor and both coils. So the heat gain would be the compressor getting warm.

Example running a dehumidifier in garage or basement you will see no real change in the temperature.

You start running a big dehumidifiers made for enough sqft to cover a shop and you will notice the heat if you're simultaneously trying to air condition the space in a hot + humid climate. Most of these are going to raise air temp 10-15 degrees between input and output. In a small costco style dehumidifier it's not moving enough air to really make a dent, I agree. If you size up to something like a ULTRA AIRE XT205H which is moving 450-500CFM and run it nearly constantly, it's a load you may need to deal with if you're trying to cool and dry a large workshop space.


It could be not noticable, but it could impact his cooling load slightly as well. In a world where HVAC is being constantly lambasted for over-sizing it's important to have all the inputs available if you want to cut it that close!

 

[Showkey]

Best to include all the information like:

*The temperature increase in the supply or discharge air, compared to the incoming air stream, will vary between 15° – 25° depending on the load the dehumidifier has to take on. However, this does not mean that your home will increase in temperature by 15° – 25°.
The air is mixed with the rest of the air in the home and distributed evenly by utilizing the HVAC ductwork that is already in place. In addition, for every degree that you increase the temperature, the relative humidity will drop an average of 2%. Therefore, the home will typically experience no more than a 2°-4° increase in temperature as long as the dehumidifier control is dialed into a reasonable setpoint (77° and 45% relative humidity is recommended by ASHRAE). Setting the RH% too low (ex: 35%RH) will result in further run time on the unit and additional heat output.

* from the Santa Fe web site.