Dehumidifying a hangar

poadeleted21

poadeleted21

Touchdown! Greaser!
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Went to the hangar this weekend, floor was damp, plane covered in dew. Opened the cowling a little corrosion on the spark plug caps and alternator.

Short of finding a climate controlled hangar, anything else you can do?
 
bartmc said:
Went to the hangar this weekend, floor was damp, plane covered in dew. Opened the cowling a little corrosion on the spark plug caps and alternator.

Short of finding a climate controlled hangar, anything else you can do?
Click to expand...

What material is your hangar made of?

José
 
bartmc said:
Short of finding a climate controlled hangar, anything else you can do?
Click to expand...

Not really. We put dehumidifiers in spaces we wanted to keep dry. Expensive to run. You can try a light bulb under the cowl to keep it above the dew point but it's impractical to try to protect the entire airframe that way.
 
Let some sunlight in to warm your concrete floor which will help prevent all of that humid air from condensing on cold surfaces. Install a ceiling fan or use a portable fan to get some air moving. Provide some outside ventilation if possible. I have two 40 watt worklights near my exhaust/cowl outlet, keeping the engine compartment 20F above ambient. I feel the relatively cool bulbs do not pose a fire risk and I like having redundancy. These keep my oil and engine a little warmer and prevent corrosion. The only corrosion on my 130 hr old engine is on the exhaust possibly due to extreme heat. A dehumidifier plumbed to the outside would help if your hangar was fairly airtight, but not much otherwise.
 
Clark1961 said:
Not really. We put dehumidifiers in spaces we wanted to keep dry. Expensive to run. You can try a light bulb under the cowl to keep it above the dew point but it's impractical to try to protect the entire airframe that way.
Click to expand...

We think alike. You have been there too I see.
 
Ventilation will help a lot. When things dry out seal the floor with a good concrete sealer or epoxy paint and it will greatly reduce the moisture in the future.
 
The worst thing you can do is to seal the floor with epoxy paint. Straight concrete that can absorb some water will keep things dryer.
 
I second the moving air. Maybe mount a small exhause fan in the back wall to get air moving through it.
 
The intake and matching exhaust fan is a good idea, getting ones that seal closed when you turn it off is a good idea (intake/exhaust during a dry day, seal up during the humid days).

Another option would be sealing out as much moisture as possible. It will not be close to perfect but will help the hanger air stay as dry as possible during a week or so of humid weather. Take something that can produce dust or smoke and go around the interior hanger wall on a windy day and see if any of the smoke gets sucked into (or away from) the hanger walls. There's a large air leak there, seal it with the spray foam. Making sure the hanger door seals properly will obviously help as well. This will also have the double effect of keeping insects and pests out of the hanger.

As for sealing the slab, that actually isn't a bad idea. Concrete is typically about 20% porosity (percent empty volume), this allows it to act like a sponge and it will pull up moisture from the ground and the air. If it was built properly they put a vapor barrier below the slab to prevent this but prefab metal aircraft hangers are not exactly built to the highest standards and this could have been omitted or not done properly. As for pulling moisture from the air it's actually more likely to hold in moisture during the moist days and then release it into the hanger during the dry days preventing the hanger from airing itself out. Thus, a sealer will cause the slab to have to find other ways to expel it's entrained moisture, hopefully back outside where it belongs.

If you ever look at building codes they typically required about 8 or so inches of space between the ground and the bottom edge of the siding. In addition to keeping people from burying their wooden wall studs in the ground, this is designed so that there is a region of bare concrete foundation wall exposed. Thus, if someone finishes their basement and their foundation walls pull in some moisture from the earth it will naturally try to escape in that 8" gap to the air and not take the harder route through your nice basement walls. Yay, no mold.

Lastly, I've heard of people using bags of charcoal briquettes or kitty litter in storage units to trap moisture. Change the bags out every month or so is what I'm reading is recommended. Can't hurt and it will absorb some moisture but I suspect if you did the math it wouldn't do that much for you in something as large as a hanger.

(Note, I'm a structural engineer so I know a little bit of what I'm talking about but I don't deal with building envelopes as much as I would like so please double check my comments.)
 
bartmc said:
Went to the hangar this weekend, floor was damp, plane covered in dew. Opened the cowling a little corrosion on the spark plug caps and alternator.

Short of finding a climate controlled hangar, anything else you can do?
Click to expand...

So engine makers might actually have a good argument on the 12 years or XXXX hours whichever is first TBO?
 
kgruber said:
The worst thing you can do is to seal the floor with epoxy paint. Straight concrete that can absorb some water will keep things dryer.
Click to expand...

I would bet there is no vapor barrier under the slab and it will absorb moisture from the ground and expell it into the air in the hangar. An easy way to tell if it is coming up through the slab is to tape a piece of clear plastic down on the floor and look at it the next day when the air is cool and see if it has water under it. If the moisture is on top of it then it is in the air. If it is under it then it is coming up through the floor. Stop the moisture and ventilate !!!!.
 
Vaflier said:
An easy way to tell if it is coming up through the slab is to tape a piece of clear plastic down on the floor and look at it the next day when the air is cool and see if it has water under it. If the moisture is on top of it then it is in the air. If it is under it then it is coming up through the floor. Stop the moisture and ventilate !!!!.
Click to expand...

Nice trick, I'll have to remember that one.
 
It's a T-Hangar standard issue with the sliding doors. I think it's just on low ground and water came in. it was mostly dew.

The A&P on the field told me to get used to it and recommened some stuff from spruce to spray on "things" I keep the plane CorrosionXed but he said it was something else I could get for stuff inside the cowling.

Thought maybe someone had used something like this;

http://www.homedepot.com/p/DampRid-64-oz-Hi-Capacity-Moisture-Absorber-FG50T/100391308
 
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bartmc said:
It's a T-Hangar standard issue with the sliding doors. I think it's just on low ground and water came in. it was mostly dew.

The A&P on the field told me to get used to it and recommened some stuff from spruce to spray on "things" I keep the plane CorrosionXed but he said it was something else I could get for stuff inside the cowling.

Thought maybe someone had used something like this;

http://www.homedepot.com/p/DampRid-64-oz-Hi-Capacity-Moisture-Absorber-FG50T/100391308
Click to expand...

Sounds like exactly the problem I've had with the crappy T-hangars here at ORF.

I ended up moving in to one of the corporate hangars.

What was the product from Spruce that your A&P suggested?
 
Denny-o here. Old time plant engineer. The only workable answer was kind of glossed over, twice. Let me expand on them.

FIRST: The visible moisture on the airframe is because the metal is colder than the air - and cold enough that it is below the dewpoint which causes condensation on the cold surface. (remember that second temperature number that the AWOS babbles about?)
SECOND: Short of a properly built and expensive building with insulation, etc. you are not going to lower the moisture content of the air rapidly infusing into the hangar on its way to somewhere else with gadgets.
So, what's a girl to do? - ahem :D - I mean a pilot.
ANSWER: More air :goofy:
As was suggested TWO fans. One to pull air into the hangar and one to push it back out.
So, why does adding more air NOT make the problem worse?
Because the flowing air will try to keep the airframe at the same temperature as the air around it (well, close enough for government work) Aluminum and steel can change temperature rapidly when subjected to airflow. Whereas the airmass seeping through the hangar changes temperature slowly so that the airframe will keep up with those changes and not lag behind and fall below the dewpoint and condense water out of the air.
 
Dr. O said:
Denny-o here. Old time plant engineer. The only workable answer was kind of glossed over, twice. Let me expand on them.

FIRST: The visible moisture on the airframe is because the metal is colder than the air - and cold enough that it is below the dewpoint which causes condensation on the cold surface. (remember that second temperature number that the AWOS babbles about?)
SECOND: Short of a properly built and expensive building with insulation, etc. you are not going to lower the moisture content of the air rapidly infusing into the hangar on its way to somewhere else with gadgets.
So, what's a girl to do? - ahem :D - I mean a pilot.
ANSWER: More air :goofy:
As was suggested TWO fans. One to pull air into the hangar and one to push it back out.
Click to expand...

Yeah, my idea of spray foaming and trying to seal air leaks is useless if actual groundwater is seeping in. Sealing the slab will still help with that but not as much.

If you're unable to remove the moisture from entering the hanger then keeping it off the plane is the next best thing. Two fans will help prevent moisture condensation on the aircraft and ensure that when the air gets dryer outside your hanger doesn't trap the moisture in there.

The 40 watt worklights in the cowls will help a lot with the engine compartment as people have stated before and if you can position the fans such that they blow across the aircraft then you'll have your best evaporation rate in addition to circulating air in and out.
 
I have two hangars at the Bremerton Airport, which is built on an old swamp.

I keep a floor squeegee in the one with the epoxy floor, because every time there is a "pineapple express" the place is drenched.

The other hangar has no coating and stays dry.
 
tehmightypirate said:
Yeah, my idea of spray foaming and trying to seal air leaks is useless if actual groundwater is seeping in. Sealing the slab will still help with that but not as much.

If you're unable to remove the moisture from entering the hanger then keeping it off the plane is the next best thing. Two fans will help prevent moisture condensation on the aircraft and ensure that when the air gets dryer outside your hanger doesn't trap the moisture in there.

The 40 watt worklights in the cowls will help a lot with the engine compartment as people have stated before and if you can position the fans such that they blow across the aircraft then you'll have your best evaporation rate in addition to circulating air in and out.
Click to expand...

You will spend more on spray foaming then the plane cost..:yikes:
 
N801BH said:
You will spend more on spray foaming then the plane cost..:yikes:
Click to expand...

I think you misunderstood, read my original post. I'm not talking about trying to insulate the walls (which look insulated from the OP's profile picture) but rather using the rattle can spray foam to seal up air leaks.

kgruber said:
I have two hangars at the Bremerton Airport, which is built on an old swamp.

I keep a floor squeegee in the one with the epoxy floor, because every time there is a "pineapple express" the place is drenched.

The other hangar has no coating and stays dry.
Click to expand...

Hmmmm, that's a head scratcher for sure. Not sure why you would see such a huge difference unless there's actually a leak in your epoxy hanger somewhere.
 
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bartmc said:
It's a T-Hangar standard issue with the sliding doors. I think it's just on low ground and water came in. it was mostly dew.


Thought maybe someone had used something like this;

http://www.homedepot.com/p/DampRid-64-oz-Hi-Capacity-Moisture-Absorber-FG50T/100391308
Click to expand...
I would guess that you need to remove gallons per day to get the humidity down in a T hangar on a slab over low ground (I pull a couple gallons per day out of my basement during the summer). That would mean you would have to go through at least a handful of those per day.
 
Capt. Geoffrey Thorpe said:
I would guess that you need to remove gallons per day to get the humidity down in a T hangar on a slab over low ground (I pull a couple gallons per day out of my basement during the summer). That would mean you would have to go through at least a handful of those per day.
Click to expand...


And more than that once you open the hangar door and have to start over.
 
I had the exact same thing happen in my hanger. snow melt and no drainage and my hanger had 1/4 inch of water everywhere. I put one of those large fans and aimed it at the floor and overnight it almost dried everything up. just get a big fan at the hardware store.
 
Fearless Tower said:
Sounds like exactly the problem I've had with the crappy T-hangars here at ORF.

I ended up moving in to one of the corporate hangars.

What was the product from Spruce that your A&P suggested?
Click to expand...

LPS I believe it what he was talking about.
 
Yes, I did forget to mention the use of LPS 1 and LPS 2 to help keep corrosion down. Expensive but a very good product.
 
Can you use LPS on engine components? That seems to be where I have noticed the primary corrosion start showing up- on the cylinder baffles and engine cases.
 
Dr. O said:
Denny-o here. Old time plant engineer. The only workable answer was kind of glossed over, twice......
Click to expand...

Dang it, Denny! This thread has been quite entertaining to read. Why'd you have to go and spoil it by providing the correct answer?
 
Fearless Tower said:
Can you use LPS on engine components? That seems to be where I have noticed the primary corrosion start showing up- on the cylinder baffles and engine cases.
Click to expand...

LPS 2:
Auto-Ignition Temp >442F.
Flash Point= 175F.

I don't use LPS on engine cases, cylinder heads, exhaust due to excessive heat. LPS is safe on painted surfaces. I use it on all hinges. I use Mouse Milk on exhaust hardware and joints. I keep it to a minimum as vapors can ignite. I mostly use the two 40 Watt bulbs to prevent engine corrosion.

Mouse Milk:
Ignition Temp= 535C.
Flash Point > 4C.
 
RV10flyer said:
LPS 2:

Auto-Ignition Temp >442F.

Flash Point= 175F.



I don't use LPS on engine cases, cylinder heads, exhaust due to excessive heat. LPS is safe on painted surfaces. I use it on all hinges. I use Mouse Milk on exhaust hardware and joints. I keep it to a minimum as vapors can ignite. I mostly use the two 40 Watt bulbs to prevent engine corrosion.



Mouse Milk:

Ignition Temp= 535C.

Flash Point > 4C.
Click to expand...

Thanks!
 
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