Crawlspace Dehumidifiers

[b-boy]

Not garage related, but I have some issues in my late 1800s house.

The house has a basement that covers 3/4 of the building. The remaining area is a crawl space next to an abandoned cistern. The total area over the crawls space/cistern is ~300 sq ft.

Both areas were spray foamed a few years ago. Part of the reason for that was to eliminate the cold floors in the back of the house. The floors are tongue and groove plank nailed right over the joists. There is no subfloor, so we got a lot of cold air. The spray foam sort of fixed the coldness issue, but not as much as I'd hoped it would.

In addition to spray foam, the contractor also added plastic vapor barrier to the floors/walls of the crawl space/cistern.

During times of high humidity (like now) we get musty smells in the back of the kitchen and the back room. Both areas are over the subfloor. The kitchen is over the cistern, and is the worst offender. You can literally walk from the front of the room to the back, and the smell starts as soon as you hit the cistern area.

I'm thinking of getting a crawl space dehumidifier for this area. Do you think this could help solve the problem?

Any advice?

 

[Jakemedic]

I have one I got with the house we are currently in. It too is sealed and it does have a dehumidifier in the crawl space. I have only been here for 8 months but seems to pull quite a bit of water. It drains into the sump pump via a hose. It smells decent there, I assume it is due to the humidity being controlled well. From what I have seen, they don’t come cheap though. The one I have retails for 1200 dollars. Hope my experience helps you! Best of luck!

 

[b-boy]

I purchased this:

https://www.amazon.com/dp/B07HCLL7FY/?tag=atomicindus08-20

Hopefully I made a good choice. The overall reviews are excellent.

I'll need to build a new insulated crawlspace entry door. The current one leaks like a sieve.

 

[n20junkie]

I stuck a home depot sourced dehumidifier with hose drain in my crawl space and it did wonders. I let it run year round.

 

[bad_idea]

While you are down there hang a remote thermometer/humidity meter. You can pick them up at HD or Lowe's fairly reasonable. Will be a thermometer with remote meter to track the outside weather and inside weather. Hang the remote meter in the crawl space to keep track of what the humidity level down there actually is.

Also, look into piping the outlet of the dehumidifier across the space to circulate the air. Basically install ducting on the outlet side of the unit across the space.

 

[b-boy]

I like the idea of the ducting. I have 2 areas in the crawl space separated by a wall. There is a 3'x4' opening between the 2 spaces. Ducting between the spaces to mix up the air makes a lot of sense.

I did order a remote meter.

 

[b-boy]

I'm a little fuzzy on what to do during the Winter. Do you normally just shut these off in late Fall? I know they can't handle extremely low temperatures.

 

[Jakemedic]

I'm a little fuzzy on what to do during the Winter. Do you normally just shut these off in late Fall? I know they can't handle extremely low temperatures.

I shut mine down for the winter and opened a duct slightly for heat in the crawl space. Not sure if it was right to do that, but it appeared to work well till I crawled down and restarted the dehumidifier in the spring.

 

[Showkey]

I'm a little fuzzy on what to do during the Winter. Do you normally just shut these off in late Fall? I know they can't handle extremely low temperatures.

Really is highly dependent on your location........south Texas or Kansas would be different from Iowa or Minnesota.

 

[b-boy]

I'm in Buffalo, NY so my weather is closer to Minnesota than Texas.

 

[nafterclifen]

My sealed crawlspace stays about 50 degrees all year round. But humidity down there only rises in the summer, upwards of 75%. So in the spring when I turn OFF the whole house humidifier, I turn ON the crawlspace dehumidifier to bring it down to about 45%. And then in the fall, I turn ON the whole house humidifier and turn OFF the crawlspace dehumidifier.

 

[Kaizen]

Op damn that is an expensive dehumidifier. Mine was only a couple hundred and works fine. They all die a few years after the warranty. Couple of questions. Is the cistern empty or in use? Is it covered? Does the crawl space have any foundation vents? I’m thinking you instead should get air movement with a few foundation vents. If the space is all insulated it can remain open year round and that area is now an ungrateful area


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[nafterclifen]

Does the crawl space have any foundation vents? I’m thinking you instead should get air movement with a few foundation vents. If the space is all insulated it can remain open year round and that area is now an ungrateful area

I have foundation vents but I plugged them with 2" rigid foam insulation. Why let cold air flow in during winter and hot, humid air flow in during summer? It'll only make conditions worse. That air, in my case, would leach into the house and sub-floor. I certainly don't want that. Of course not all crawlspaces are like mine. Each should be handled individually depending on conditions, climate, etc.

 

[Kaizen]

I have foundation vents but I plugged them with 2" rigid foam insulation. Why let cold air flow in during winter and hot, humid air flow in during summer? It'll only make conditions worse. That air, in my case, would leach into the house and sub-floor. I certainly don't want that. Of course not all crawlspaces are like mine. Each should be handled individually depending on conditions, climate, etc.

Right mine neither but op stated they spray foamed his and he can close it off so if all the pipes are sealed I bet air movement will take care of the problem. When op answers the other questions we will see. Interested in the amount of water down there and if that plastic gets moisture under it.



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[Barrytomia]

Please forget about the whole moisture issue. I DON"T what that air returned to the living area. I just dont. All I want to do is two things.

A. Lower the cabin temperature, by pushing warm air from the ceiling into the crawlspace.

B. Keep the crawlspace above 33 degrees.

Do you have suggestions on doing this and only this........???

 

[Kaizen]

Please forget about the whole moisture issue. I DON"T what that air returned to the living area. I just dont. All I want to do is two things.



A. Lower the cabin temperature, by pushing warm air from the ceiling into the crawlspace.



B. Keep the crawlspace above 33 degrees.



Do you have suggestions on doing this and only this........???

Confused?? How many houses can we talk about? All have different needs. Make another post with yours


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[BD1]

Dehumidifier will definitely help, cheap $$$ to find out.
Many newer ones have a built in pump too, so you may have to remove it for winter to a above freezing area.

 

[fitter30]

Debumidifiers from box stores do not have a certified rating. AHAM is the professional rating system.If you will be using your dehumidifier in a tough environment with very damp conditions, look for a dehumidifier with your recommended pint capacity tested at AHAM conditions (average humidity conditions of 60%) instead of saturation (100% humidity)​. A model able to remove 70 pints of water when the air is saturated, for example, is much less robust than a model able to remove 70 pints of water at AHAM conditions. A good RH in crawlspace is between 45-50% to keep mold at bay.

 

[dereksummers]

Not garage related, but I have some issues in my late 1800s house.

The house has a basement that covers 3/4 of the building. The remaining area is a crawl space next to an abandoned cistern. The total area over the crawls space/cistern is ~300 sq ft.

Both areas were spray foamed a few years ago. Part of the reason for that was to eliminate the cold floors in the back of the house. The floors are tongue and groove plank nailed right over the joists. There is no subfloor, so we got a lot of cold air. The spray foam sort of fixed the coldness issue, but not as much as I'd hoped it would.

In addition to spray foam, the contractor also added plastic vapor barrier to the floors/walls of the crawl space/cistern.

During times of high humidity (like now) we get musty smells in the back of the kitchen and the back room. Both areas are over the subfloor. The kitchen is over the cistern, and is the worst offender. You can literally walk from the front of the room to the back, and the smell starts as soon as you hit the cistern area.

I'm thinking of getting a crawl space dehumidifier for this area. Do you think this could help solve the problem?

Any advice?

We had a similar issue with our crawlspace, and well, the dehumidifer (ours is AlorAir), keeping the humidity in the 50s percent or so, has virtually eliminated the odor - in the house at least, though it's still somewhat noticeable in the crawlspace.
I did get it in May after humidity levels kept pushing above 70%. I was afraid that it would use a lot of electricity, but I haven't noticed any significant increase in our bill since then.

Also, make sure your duct work is properly sealed, as even new ductwork can have issues. Ideally, should use mastic sealant.

And if smell stays, then maybe it's worth investigating if there's a mold growing?

 

[b-boy]

I installed my dehumidifier, ran ductwork between sections of the crawlspace, and added a remote monitor. The dehumidifier is suspended from the joists. I drain it out through the wall via PVC pipe.

I also built a new access door. I added 4" of foam board and a rubber gasket to seal the area. I made it as airtight as possible.

The space stays at about 35%. The unit runs intermittently. It made a big difference. The smells are significantly reduced, but not totally eliminated. The crawlspace itself smells a lot better.

 

[D45]

I am wondering, how or where can I run a drain hose in my crawl.......drill a hole in the poured wall doesn't seem fun

 

[Jackfre]

Here you go.

https://www.tjernlund.com//crawl_space_ventilation.htm

 

[b-boy]

Here you go.

https://www.tjernlund.com//crawl_space_ventilation.htm

This is the exact opposite of what I did. I think this approach depends on your climate. In Buffalo, the recommendation has been to encapsulate and dry out the encapsulated air.

My biggest issue was that during the Summer all the hot, humid air got pulled into the crawlspace. My Humidity levels were 60%+. That's what they were outside as well, so drawing in all that exterior air wouldn't have solved the problem.

Now I'm seeing constant 35% levels down there. The chipmunks that have invaded the space seem to be enjoying it. They say it's much more comfortable now.