Condensation!

[F10]

My rental hanger has a dirt floor, with carpets over it, recently noticed a lot of condensation on the engine, after a old night, which was alarming! I keep the aircraft under cloth covers. Recently put a blue plastic tarp over it, in winter only, due to dripping condensation from the hangar roof🤨...in summer it’s all good and does give great rain and wind protection of course. But, lots of different opinions on the net...some say heaters good..but others insist they make corrosion worse...I agree with, “run the engine at least once a week”....that means fly it, not a short run, that’s also bad...I close up the cowling, should I bung the exhausts? Tough one.....

[IBob]

F10, I have done a lot of refrigeration control work in freezing works.

Vegans should look the other way at this point.
A particular area of difficulty was the marching beam chillers, where the carcases come off the killing chain warm and wet and are fed along a progressively chilled room to age then reduce biological action. The steady stream of carcases is constantly bringing moisture into the room, and the walls and ceiling at the intake end would stream with condensation for a couple of hours after each shift start. This is a meat hygiene nono, so we had people in there with squeegies etc trying to control it.

At one particularly bad plant we tried all sorts of things: extra fans blowing air various ways, a low temp refrig coil at the front end to strip moisture.

Improvement was minimal.

 

Then one day I was talking with a visiting eng and he said 'You will only get condensation where the surface is colder than the ambient air".

I thought about that, then programmed an especially long hot defrost of the refrig gear at the front of the room, timed to occur before start of shift.

 

In the case of something like an engine, I think I would be keeping it warm, but also shrouding it somehow to avoid constant air circulation.
And the condensation vanished.

By hot defrosting the intake area prior to startup, we were warming the walls and ceiling, so no condensation took place when the moisture began to arrive. And thereafter the walls and ceiling would go to ambient air temperature, so still no condensation.

 

So, the best way to avoid condensation is to keep the air dry.

But if you can't do that, another option is to keep equipment warm. 

 

Edited July 4, 2021 by IBob

[IBob]

I should add that I noticed parts from my build sometimes 'sweating' on the shelves in my workshop. This was particularly the case with the aluminium prop extension and the wheels, both of which are solid aluminium turnings or castings.

The process here was that those parts cooled overnight, but due to their large thermal mass, were slow to warm up as the day warmed up. So as the day warmed, those parts remained colder than the ambient air, and condensation would occur, just like a cold glass of beer: the sweating occurred not overnight, but in the mornings as the ambient air temp began to climb.

I was able to fix that by moving those heavier parts to higher shelves, so keeping them warmer. I also improved the seal around the workshop door to reduce the ingress of air.

[skippydiesel]

On the original  Q,  I would speculate: 

 

From my own observation ( & a smidgeon of science) I support IBobs theory, that is where you have warm moist air, coming into contact with a cold surface (or air mass) the moisture will condense (free water/rain).

 

In an uninsulated structure eg tent, corrugated iron shed, even car windows, It is not unusually to have "sweating"  on internal walls.

 

I would suggest that the warm (carpet insulated) moist (permeable to ground water) floor is maintaining a higher temperature than the outside air. This will be particularly evident in the early morning.

 

The warm moist air inside the shed is condensing on the cold roof/ceiling & walls - not on your aircraft (its getting wet from the internal rain). 

 

Of course you can get condensation forming on your aircraft - again this is where your aircraft (usually parked outside over night) is colder than the warming moist air of the morning.

 

If you are concerned about condensation forming inside your engine there are only three possible preventions:

• Keep the engine warm, relative to the air where it is hangered
• Plug all external ports where moist air may get access
• Both of the above

[IBob]

Seems I stuffed up the format of my first post here:

"In the case of something like an engine, I think I would be keeping it warm, but also shrouding it somehow to avoid constant air circulation."

was supposed to be at the end.

[turboplanner]

2 hours ago, F10 said:

My rental hanger has a dirt floor, with carpets over it, recently noticed a lot of condensation on the engine, after a old night, which was alarming! I keep the aircraft under cloth covers. Recently put a blue plastic tarp over it, in winter only, due to dripping condensation from the hangar roof🤨...in summer it’s all good and does give great rain and wind protection of course. But, lots of different opinions on the net...some say heaters good..but others insist they make corrosion worse...I agree with, “run the engine at least once a week”....that means fly it, not a short run, that’s also bad...I close up the cowling, should I bung the exhausts? Tough one.....

I have a lot of farm machinery in a big shed which is part concrete floor. There's an old rule in farming that equipment parked on concrete doesn't rust and parked on the dirt section, does, and that includes things like Sidchrome tools. Things like shovels, mattocks, picks take on that antique look with fine speckled rust after a few years, so I rotate equipment and regularly sand and paint items stored above the dirt. The moisture is drawn up through the ground and I presume evaporates upwards throughout the warm day.

 

The whole shed gets the condensation you describe on the underside of the roof, but the tools and equipment on the concrete don't rust.

 

Where I've needed to store something expensive on the dirt, I've pegged a tarp out on the ground and that works.

 

Maybe you could experiment by pegging out a small tarp and put some things that rust quickly on it and some straight on the dirt, or just peg a big tarp out, put your aircraft on it and see if it makes a big difference.

 

 

 

 

 

[F10]

Will try putting down a tarp on the floor, that sounds interesting, and will close off engine better. Heating not an option, no power unless I can try a solar panel but that will start to get complicated, we have many cloudy days! Trouble is, will an open engine dry off faster? We’ve also had a lot more winter rain here at Yarram then in the past few years....very wet, but as I said, will definitely run the engine once a week, roll on spring!

[skippydiesel]

1 hour ago, F10 said:

Will try putting down a tarp on the floor, that sounds interesting, and will close off engine better. Heating not an option, no power unless I can try a solar panel but that will start to get complicated, we have many cloudy days! Trouble is, will an open engine dry off faster? We’ve also had a lot more winter rain here at Yarram then in the past few years....very wet, but as I said, will definitely run the engine once a week, roll on spring!

Just remember the physics - if security not an issue might be more effective to leave doors open for a through draft.

[ClintonB]

My workshop rained coffee coloured water on everything, every night until I pulled the roof sheets of nd fitted Aircell insulation, now no more raindrops. It is like bubble wrap made from foil. It is not cheap (around 300 for 30m by 1.3m roll) if you get in and do with hanger owner to save on labour it will make a big difference. Knocks the heat out of the shed in summer, which will help with heat sensitive aeroplane parts.

 

[Flightrite]

I keep moisture absorbent crystals in my engine compartments, no more wet engines:-) Amazing the water i collect on certain cold damp clear nights.

[spacesailor]

Has any one tried those boxes that collect danpness ( Damprid ),   from the supermarket laundra section. 

spacesailor

[Flightrite]

15 hours ago, spacesailor said:

Has any one tried those boxes that collect danpness ( Damprid ),   from the supermarket laundra section. 

spacesailor

see my post above!

[spacesailor]

I don,t think those Damprid are crystals! .( revive, interior dehumidifiers   ) it is has white pellets above a gey collection area.

I could be wrong, but the cats ' litter tray ' crystals are completely different  ( in looks  ) .

spacesailor

[onetrack]

Most moisture-absorbing crystals are the chemical known as "Silica gel". This product is an amorphous and porous form of Silicon Dioxide. Silicon Dioxide is seen in its most common form as quartz.

 

https://en.wikipedia.org/wiki/Silica_gel

 

Damprid is a combination of chemical crystals that have moisture-absorbent properties. The main ingedient in Damprid is anhydrous (meaning "no water") calcium chloride, with trace amounts of sodium chloride (salt) and potassium chloride.

These chemicals are called deliquescent compounds, as they have the ability to absorb large amounts of water from humid air, often turning mushy as they do so, due to the amount of water absorbed.

 

If you heat them, you can evaporate the water and use them again. However, the heating must be gentle, or you risk destroying the chemical bonds of the compounds.

[spacesailor]

Thanks for that information,  onetrack.

spacesailor

[spacesailor]

The wife has 'large packets ' of moisture/odor absorbant crystals. For her joggers, purchased fron the " dollar store  ".

They look good & they,r  cheap !.

spacesailor

[Bruce Tuncks]

I like the tarp under the carpet idea. If the source of moisture is the damp ground, an impermeable membrane ( plastic tarp) will cut it off.

I have seen the same thing here with gliders in tee hangars. And I have seen it cured with cutting off the ground moisture.

[RFguy]

F10. I bet Yarram as a fairly high water content this year.
I would suggest keeping it well aired. and on a pegged out tarp.

 

and warm with an electric blanket thrown over the cowling. power I here you say ?

 

For power, this can be done cheap...  buy some removed solar panels from Gumtree, there are lots of 180 Watt  etc panels pulled out, they'll sell for near free. scrap value. (current panels are 300-400W) .

You can put a tech screw through the frame from underneath, just a dob of grey roof and gutter sealant (netural cure) where the panel frame mates the roof. maybe a bit of zinc compound if its on something nice.

Put up to 120V max worth of panels in series, (probably 4 or 5), and power the electric blanket directly, leave on max (but it is half voltage so is quarter power/quarter the heat).

just an idea.

 

agree on concrete versus non concrete floor comments.and pegged out tarps are very useful.