Crawl space dehumidifier just died of Covid

thebrotherinlaw

thebrotherinlaw

Well-Known Member
Joined
Dec 8, 2014
Location
WNC
The ol girl has been a good one. It was a Fral (snooty and made in Italy) and lasted 10 years. Anybody had any success with a particular brand? Thanks
 
Did someone say Keith Stone?
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Mac5005 said:
Keystone, off amazon or amazon basics.


Seriously.

If you just want to spend a lot more then aprilaire, but what you get vs the cost....

Stay away from Santa FE, Honeywell, alorair, horizon, and about 2 dozen other brands etc.
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Thanks for the info. I'll check them out.
 
shawn said:
Will one of those little guys do 2500-3000sf of crawl space?
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Yep if it’s actually air sealed. They have 30/50/70 pint models but it gets confusing bc they changed the rating name this year.

This is a yes especially if it’s a crawlspace is actually air sealed and is already dry.

At that point the dehumidifier is only maintaining the dew point and not trying to lower it. With less moisture load, less capacity is sufficient and increases ROI due to less energy cost.

Keep in mind, if the crawlspace is actually air sealed, it doesn’t matter where the dehumidifier is placed. The enveloped air mass will seek equilibrium.

So you can dry it here, there, or over there, and it dries the entire air mass.

All of that requires it to be actually air sealed.

When others use larger dehumidifiers, it’s typically to cover up their own poor air sealing, or lack of.
 
shawn said:
That's a tall order with a gas pack.
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Gas pack combustion air should be plumbed to exterior.

It should never use crawlspace air for intake or exhaust.

Having a closed/conditioned crawlspace not air sealed, is exactly the same as running HVAC with windows open.

I use a 50cfm exhaust fan to negatively pressure the crawlspace with no effect on Dehu sizing. Given, my make up air for that leaks in from first floor penetrations and not from exterior.
 
JoshRountree said:
Are two Keystone's equivalent to one Aprilaire? Lol

Is Aprilaire really not worth it?
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You could buy 4-6 keystones for the price of an aprilaire.

Aprilaire has 5 year warranty, keystone has a 1 year.

The keystone failure rate is the same as aprilaire.

The keystone are available in 30/50/70 pint.

The 1830 aprilaire is 70 pints for $1000-$1200

The 1850 aprilaire is 90 pints for $1350-1500.

Biggest flaw of the aprilaire is the drain fitting is on the side, at the bottom of the cabinet. Can be difficult to get a gravity drain to daylight without lifting up between floor joists.

Condensate pumps are relatively unreliable.

The keystone drain is 1/2 way up the cabinet of the unit, so it’s already 8” higher in elevation vs the aprilaire. It makes it that much easier to get a gravity drain to daylight, and have it be above exterior grade.
 
Mac5005 said:
Gas pack combustion air should be plumbed to exterior.

It should never use crawlspace air for intake or exhaust.

Having a closed/conditioned crawlspace not air sealed, is exactly the same as running HVAC with windows open.
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I'm talking about a package unit. It sits on the ground outside and has a couple of ~18-24" dia insulated flex ducts attached to it. You can cut some filler panels out of rigid insulation to close around the duct penetrations in the foundation wall, but getting it to actually be airtight is a tall order.
 
shawn said:
I'm talking about a package unit. It sits on the ground outside and has a couple of ~18-24" dia insulated flex ducts attached to it. You can cut some filler panels out of rigid insulation to close around the duct penetrations in the foundation wall, but getting it to actually be airtight is a tall order.
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Ahhh I’m an idiot. When I read gas pack, for whatever reason I was thinking split system/gas furnace. Facepalm

Every one of my crawlspaces has 1/2” insulation board and expanding foam sealing this wall penetration. It’s really not that difficult.

The difficult ones require the exterior duct cover to be removed and some amount of sealing done from the exterior and some done from interior.

This is a terrible wall penetration to leave unsealed.

Worse than no gasket on access door or no hardware to hold door against gasket and equivalent or worse than leaving a foundation vent open/unsealed.
 
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paradisePWoffrd said:
When you say sealed, are you including ground cover as well or just exterior air entry?

I know fully encapsulated is ideal and best for encapsulated control.
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I mean perimeter walls air sealed.

Ground vapor barrier actually doesn’t contribute much as far as moisture load. Without one yes the Dehu runs more as you are trying to dry the ground where the air meets it,

But even if there is puddled water, there is very little heat input to cause the phase change from liquid to vapor where it could then be absorbed by the wood and cause harm. Especially given the typical ground temperature.

Yes, vapor barrier vs no makes a small difference, but that difference is far less important than perimeter wall sealing.

The type of vapor barrier and specific of type/thickness poly generally make zero difference to the moisture load.

Ideally, what I shoot for, is no debris under vapor barrier to cause holes in it,

All soil covered, plastic extending up and onto curtain wall. 3-4” minimum gap from wood sill for termite inspection, and 12” above exterior grade.

The plastic on the wall makes more of a difference in the winter, when the north side wall temp can drop below the crawlspace dew point.

Overlap of plastic pieces 12” minimum, pieces pulled taught and fastened to soil every 12-16” at the overlap.

Not important to wrap interior or exterior piers as the moisture load from wicking up a CMU block isn’t enough to warrant the extra cost.

Ie: meet/exceed code for vapor barrier, and don’t cover up wires/pipes etc unless they are below grade.

Plastic pieces are installed opposite of shingles, so if any water enters for any reason, it runs downhill and under the next overlapped piece.

12” overlap and fastened is same as taped/sealed/glued overlap in terms of moisture load.
 
Mac5005 said:
I mean perimeter walls air sealed.

Ground vapor barrier actually doesn’t contribute much as far as moisture load. Without one yes the Dehu runs more as you are trying to dry the ground where the air meets it,

But even if there is puddled water, there is very little heat input to cause the phase change from liquid to vapor where it could then be absorbed by the wood and cause harm. Especially given the typical ground temperature.

Yes, vapor barrier vs no makes a small difference, but that difference is far less important than perimeter wall sealing.

The type of vapor barrier and specific of type/thickness poly generally make zero difference to the moisture load.

Ideally, what I shoot for, is no debris under vapor barrier to cause holes in it,

All soil covered, plastic extending up and onto curtain wall. 3-4” minimum gap from wood sill for termite inspection, and 12” above exterior grade.

The plastic on the wall makes more of a difference in the winter, when the north side wall temp can drop below the crawlspace dew point.

Overlap of plastic pieces 12” minimum, pieces pulled taught and fastened to soil every 12-16” at the overlap.

Not important to wrap interior or exterior piers as the moisture load from wicking up a CMU block isn’t enough to warrant the extra cost.

Ie: meet/exceed code for vapor barrier, and don’t cover up wires/pipes etc unless they are below grade.

Plastic pieces are installed opposite of shingles, so if any water enters for any reason, it runs downhill and under the next overlapped piece.

12” overlap and fastened is same as taped/sealed/glued overlap in terms of moisture load.
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Things have come a long way in 10 years. Encapsulated used to mean heavy lining that covered the floor and the insulation on the block exterior walls. Everyone swore you had to have that heavy vapor barrier on the ground and every joint sealed with tape. I have been properly schooled. Thanks man!
 
Mac5005 said:
This is a terrible wall penetration to leave unsealed.
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Agreed. My original point was only that it's difficult to do. Sealing vents just takes a sheet of foil faced and a can of great stuff. Sealing 2*5ft hole against a pair of flex ducts takes the better part of a roll of tape, and you're lucky if it's still in place a year later.
 
shawn said:
Agreed. My original point was only that it's difficult to do. Sealing vents just takes a sheet of foil faced and a can of great stuff. Sealing 2*5ft hole against a pair of flex ducts takes the better part of a roll of tape, and you're lucky if it's still in place a year later.
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Typically one 4x8 sheet of foil faced polyiso will do a house.

Cut into thirds. 32x 48.

Cut one of those 32x48 into 5 pieces. One is shaped like an hourglass, this goes between the supply and return ducts where they go thru the wall. Cut this from center of that 32x48.

Now with the remaining portion, leave each of the 4 corners intact. Cut a radius on the long side of these triangles. These go in each corner around the ducts going thru the wall.

Cut all these to fit tight around ducts and inside brick opening.

Then great stuff or other expanding foam all the joints and from polyiso to brick, and poly iso to duct.

No tape needed.

The other third cut into 12- 8”x16” for foundation vents.

The other third is for any porch openings or more foundation vents.
 
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thebrotherinlaw said:
Things have come a long way in 10 years. Encapsulated used to mean heavy lining that covered the floor and the insulation on the block exterior walls. Everyone swore you had to have that heavy vapor barrier on the ground and every joint sealed with tape. I have been properly schooled. Thanks man!
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Most of that is marketing and what’s pushed down consumers throats without applied science or data. Lol.

We have changed very little in our installation since 07, and even less from 99-07. Small things here and there, more and different options on things.

Fine tuned some things to create a better product without increasing the cost a ton.

I mean I used to push insulating the exterior walls. Thought it was great. Data and ROI ( and lack of) didn’t back up the hype.

Now the answer is put the insulation where it’s the cheapest to do.

Sure there are some anomalies that dictate it, but for 99%, the air mass of the crawlspace functions as the insulation for the ductwork/1st floor.
 
I bought a tosot and have been really impressed with it. It does have built in pump as well
 
Landcruzn said:
I bought a tosot and have been really impressed with it. It does have built in pump as well
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Looks very similar to keystone/amazon basics one. Should be pretty good and last you a while for the cost.

Does it have a copper or aluminum coil behind the dust screen/filter.

My only complaint with that one is the top air outlet. I try to find ones that have rear/side air outlet so in shorter crawlspaces it isn’t dumping the air straight up towards the floor/insulation. But that’s me splitting hairs for my typical use haha.


For this thread, for an already sealed and dry crawlspace a 30 pint model will work well up to 2000-2500 sq ft of crawlspace that’s not chopped up.

50 pint for 2000-3000 sq ft, and 70 pint for 3000-3500 sq ft.

A crawlspace that’s chopped up and not essentially a big rectangle or has far remote areas, or big sq ft additions with poor cross flow of air requires more capacity. The same is true for drying crawlspaces that are wet and it’s a new conversion to a closed crawlspace, more capacity is necessary.
 
Landcruzn said:
I bought a tosot and have been really impressed with it. It does have built in pump as well
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Mac5005 said:
Looks very similar to keystone/amazon basics one. Should be pretty good and last you a while for the cost.

Does it have a copper or aluminum coil behind the dust screen/filter.

My only complaint with that one is the top air outlet. I try to find ones that have rear/side air outlet so in shorter crawlspaces it isn’t dumping the air straight up towards the floor/insulation. But that’s me splitting hairs for my typical use haha.
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I have a Tosot as well. It has been running strong for a yr with no issues. I dont prefer the top outlet either. I built a deflector that sits over it and redirects the air off the back.
 
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