Hangar condensation
 

Anyone want to have a crack at explaining this one, 2 hangars side by side with a single adjoining wall with a roll up door connecting them, both constructed at the same time with same building methods and materials, both with insulated roof and walls, the sole difference is one has a 40 x 14 metal door. I go in to the one hangar and the floor is soaking the plane totally covered in condensation I mean dripping off it into puddles on the floor it's like a Panamanian jungle absolutely everything in the hangar is soaking even the old steam gauges in the aircraft panel are all fogged up , the other hangar is bone dry. How does that happen ?

Simple bit of meteorology! The most probable answer is that one hangar has a good airflow through it, the other is too airtight. Condensation occurs when the local air temperature falls below the dew point and there is no air movement (that is when fog occurs) If there is an airflow through a confined space i.e. one of your hangars any moisture that does appear will be collected (it actually sublimes) by the moving air as water vapour, a colourless gas that does no harm. That's also why it is best to leave a door or DV window open to allow some airflow in the cabin.
You can either spend a fortune heating the hangar which keeps the air above its dew point or knock a hole in both sides of the hangar.
I keep my classic cars in an Airchamber in my garage which works beautifully by blowing air through a plastic "tent" in which I leave the cars. The moving air doesn't have time to cool below its dew point, and any moisture on the car dries out very quickly. Saves a fortune in energy costs compared to heating the garage or running a dehumidifier all the time. Pity they don't make aircraft shaped Airchambers!

One may have a leak, or a failed DPM in the floor that's letting in moisture.

Also, the orientation of the building can make a difference: if one hangar has a north-facing side wall, the other will be south-facing, so one will always be colder than the other.

Don't try to heat the hangar with a gas space heater - you will release loads of water into the air, so that would be a very bad way of trying to combat the problem

FBW

:ok: I built my hangar 28 years ago, the floor is 6ins rolled hardcore, 2ins rolled road recovered tarmac, a double layer of agricultural polythene then carpeted. In that time I have never had dampness of any kind, the hangar is well ventilated. I use a garden vac to keep it clean, and you can always lie on it to work say, under the a/c .

You said one has a metal 40x14 door, so I assume the other has a 40x14 wooden door...

The two materials have a different thermal conductivity, so the metal will feel colder than the wood, and cause the dampness by lowering the internal temperature below the dew point.
We have the same thing of condensation just on the metal beams of our canvas hangar.


btw, Its the same reason why metal glider trailers are prone to dampness, when wooden ones remain dry.

The above is borne out by the fact that in my garage, (asbestos) the plywood interior is dry but the mill and lathe are dripping wet.

A technique I have used to eliminate / reduce condensation in steel shipping containers is to position several 20 litre plastic containers (dark coloured preferably) filled to approx 80% with plain old water around the container. They absorb whatever daytime heat is available and re-radiate as temps drop. Goes at least a little way toward reducing the cold period inside the container.

Piper, I have the same problem.
For the last four years the heli was kept in a barn , steel clad and concrete floor, we had no trouble with condensation at any time of the year.

This last few months I've kept it in No 3 hanger at Fife airfield and the condensation is almost as bad as you describe .

The only apparent major difference is that the farm barn was used and therefore aired daily allowing airflow through as Marchettiman says .

Don't think EGPJ will let me add some 'ventilation' holes unfortunately!

JDB, are you the guy I've seen flying around in that home built chopper? Is it a Rotaway ?

My hangar has 3 ceiling fans that always run. No condensation ever. It also is insulated and heated though.

Indeed it is Piper,

Rotorway 162 F....believe it's the only one flying up here.
Great wee thing, but always a bit of 'maintenance ' to do!

JDB, when you get it back in the air I'll trade you beach hopping in the Maule for a ride in your chopper.

Our hangar (covered with foam insulated double metal skinned panels from a dismantled hangar from nearby military base) is lined with wood shuttering, originally for security as it used to be clad with corrugated iron which got prised open for break ins.

It does however have a gap all round the tops of the walls and the sliding doors which ventilate it well.

There is never any condensation though in stonking winds some rain can get in on the nose of the a/c- for this reason we keep a Cambrai cover on the nose/cabin.

We're fortunate to have mains electricity so with a small dehumidifier and cabinet heater in the cabin the a/c smells as fresh as a daisy with no damp smells and avionics problems which were rife before we got the leccy across the farm fields.

The key however is free ventilation.

Piper, it's a deal!
Let's hope for an improvement in the weather very soon!