I hate it when this happens...

[aturner]

The problem in the northern states is bit more difficult than in the south. The floor of an unheated hanger freezes up hard and the airplane sitting over that frozen concrete will lose radiant heat to the cold floor. Airframe temp can remain below air temp, and dew point, day after day after day. Circulating air through the room just results in more condensation. I've think that throwing a bit of heat into the airframe and engine compartment is the only solution, short of heating the entire hangar. I also throw some thin styrofoam sheets and rugs under the airplane to create a thermal break between the airframe and floor. Not sure if it helps much, but it can't hurt.

[jliltd]

Great idea about the box fan. That's similar to what citrus farmers do with fans mixing the varying ambient air to protect their trees from frost. If you own your hangar you might investigate spraying the ceiling and walls with spray-in foam. We did 2" on the walls and bifold door and then 2.5" on the ceiling. You can feel the difference just walking in from the outside. Add an air circulation box fan like Dan mentioned and things ought to stay nice. With the insulation a small space heater or electric oil-filled radiator could be added. Another benefit with spray-in foam in a metal building is getting all the cracks sealed to keep wind-blown dust out in the Spring.

[Amadeus]

Originally Posted by DennisRhodes

Maybe a heat blanket or other source of heat inside the cabin could minimize this? Especially for instrumentation. Or better yet an outside the cabin heat source with duct routed to the inside. That's a lot of condensation.

I use a pet bed heater.

A heated blanket (for human beds) would be nicer and cover more area but they all have switches that cannot be turned on by my SwitcheOn box. I've considered cutting the cord on a heated blanket and installing a plug so that I could use one of these but I wasn't certain if the switch contained some sort of regulator.

Example:
https://www.petco.com/shop/en/petcos...pet-bed-heater

[DaveO]

Keeping the air temp and the building temp close to the same temp. is the key to moisture build-up. I have concrete floor, no insulation and no problem with moisture. I have abundant air vents in the hanger ceiling. Just keep the air temp the same as the outside.

[bobnoffs]

when i get this moisture and i happen to be at the hangar i set up a box fan and feed it from a timer that is set to go off in 12 hrs. at least that gets rid of it when i run into it. in the spring the floor sweats a lot as the frost is going out. again, the box fan helps warm the floor up to oat and evaporate the water.

[Piper J3]

I’m still looking at options to heat cabin interior to prevent condensation. I found a 12V 100W heater with a small fan that might do the job.

My PC680 battery is connected to an Odyssey OBC-6A battery charger 24/7 whenever the airplane is in the hanger. I can easily run this heater off the airplane battery and the charger will top off as necessary. A small 12V temperature controller can be set for 70F shutoff. The heater would be fused for safety…
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[MacCool]

Originally Posted by DaveO

Keeping the air temp and the building temp close to the same temp. is the key to moisture build-up. I have concrete floor, no insulation and no problem with moisture. I have abundant air vents in the hanger ceiling. Just keep the air temp the same as the outside.

If I heat my hangar at all, I get ice on the roof melting, which runs off to the ground in front of my hangar, then freezes. Best case….a 6 foot strip of ice and ice ridge just outside the bifold making it difficult or impossible to get the plane out. Worst case…the door freezes to the ground and won’t open. I know this from experience with a couple of bullet heaters a couple of years ago while doing a winter avionics project.

If one doesn’t have an insulated and heated hangar, best/simplest solution in this climate is to manage condensation by decreasing humidity in the engine. Fortunately (or unfortunately) up here the dew point and ambient temps in the winter are generally far enough apart that condensation on the airplane and in the cockpit doesn’t happen.

[Piper J3]

I’m still working this problem and have decided to just monitor the situation before taking any action... I just ordered two recording temp/humidity sensors and will place one in the airplane cabin and leave one out in the hanger. By comparing the two stored temp/humidity readings I should be able to tell if the cabin is getting condensation. It’s a starting point…
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[JonJay]

Metal building insulation is relatively cheap when installed during construction. They make products simply called “metal building insulation”, a roll of fiberglass faced with a vapor barrier. It’s rolled out before the sheet steal is screwed down. Unfortunately, many hangars are built just like the one shown on the opening page that is for rent. Nothing.
Insulation and venting avoids the condensation problem. Adding insulation to an existing metal building is doable but not easy or economical.

On the Coast, I heat with forced air to 60deg. F and have a commercial dehumidifier. Electricity is cheap here but it is still an expensive bill in the winter. I keep the hangar at 50% or better humidity. Nothing corrodes and I don’t need to preheat! Not an option for everyone especially those in cheaply built rental hangars.

[rv6n6r]

I too get condensation in the hangar sometimes (OR coast). I have one of these that I keep on the floor of my cockpit in the winter. No fan just some low heat. I honestly don't know if it does any good but I feel like it can't hurt. It does mean the seats aren't so hard when I first get in