A Condensation Question

Lambeth Cali · Dec 8, 2022

I have just put together a surprise Xmas gift and hidden it in the van.
It is a table football game, quite large and made out of MDF and metal tubes.

Can any condensation experts tell me if the condensation in this freezing weather will rust the metal and cause the MDF to crumble?

I put a thin duvet over it. Partly to disguise it.

Nobody is sleeping in the van so will condensation be negligible?

yossarian · Dec 8, 2022

Lambeth Cali said:
I have just put together a surprise Xmas gift and hidden it in the van.
It is a table football game, quite large and made out of MDF and metal tubes.

Can any condensation experts tell me if the condensation in this freezing weather will rust the metal and cause the MDF to crumble?

I put a thin duvet over it. Partly to disguise it.

Nobody is sleeping in the van so will condensation be negligible?

If you crack a window you should have zero condensation.

Alan Andrews · Dec 8, 2022

yossarian said:
If you crack a window you should have zero condensation.

and/or buy some condensation traps. They are not expensive.

Lambeth Cali · Dec 8, 2022

The van had ice on the outside this morning. Surely cracking a window isn’t going to help!?

WelshGas · Dec 8, 2022

Lambeth Cali said:
The van had ice on the outside this morning. Surely cracking a window isn’t going to help!?

Did it have ice on the inside?

Cracking the window to ventilate the interior means the humidity level inside will equal outside 24/7.
You get condensation inside when the humidity level is high and the air cools. Cooler air carries less moisture so the excess condenses out on any cold surface.

Corradobrit · Dec 8, 2022

But if you are not occupying the van and using the heater then condensation will be minimal

Alan Andrews · Dec 8, 2022

Assuming that the table is collapsible or disassembled, then put the table in a plastic bag, then seal the bag with condensation traps or a bag of silica gel crystals inside.

Lambeth Cali · Dec 8, 2022

Corradobrit said:
But if you are not occupying the van and using the heater then condensation will be minimal

Yes ok that’s kind of what I was hoping. But required confirmation.

I have the option of taking the table football around to a friends house, having turned down another friend’s shed. Unfortunately he has two teenage boys. So will a moderately cheap table football game get damaged most two weeks in a freezing van or two weeks in a house where it seems likely two boys will play on it?

I‘m not expecting this forum to answer that. Merely clarifying!

I think, like a pendulum, I am swinging back to leaving it in the van?! Table football you may remember is a game that often gets people shoving and whacking it to move a ball that is stuck, not moving or out of reach.

Lambeth Cali · Dec 8, 2022

Alan Andrews said:
Assuming that the table is collapsible or disassembled, then put the table in a plastic bag, then seal the bag with condensation traps or a bag of silica gel crystals inside.

I cannot get any traps atm.
The metal rods kind of made re-wrapping it a no no.
thanks tho

Keith Smith · Dec 8, 2022

MDF is very susceptible to moisture and cold. If the van gets cold in the night then warms in the day chances are condensation will form within the van. As suggested putting it in a completely sealed plastic bag would protect it otherwise I’d take it round to a friends.

yossarian · Dec 8, 2022

Outside relative humidity will typically fluctuate between about 70% - 100%. Van temperature will lag changes in outside temperature due to thermal mass and be a little higher if there is any insolation.

With a window cracked and no sources of moisture inside the van it's hard to picture any conditions that will create any significant condensation. Fog I guess is a technically a minor risk. In general any condensation will happen outside the van not inside.

Hawthorn37 · Dec 8, 2022

If you’re not using the van, the chances of the table getting damp is extremely low. If the metal parts are made of uncoated mild steel and exposed to cold air then there is a small chance of surface rust, but as you’ve covered with it a duvet, the risk is minimal. The very cold frosty weather actually helps as this drops moisture out of the air and so lowers the relative humidity, and the water content of the air is low, around 3g per cubic metre.

To be scientific, if the current air temperature is 0C and Relative Humidity is 80% (it’s about that now), then - using a Physcometric Chart - the point at which condensation forms, the Dew Point, would be around -4C.

yossarian · Dec 8, 2022

Hawthorn37 said:
If you’re not using the van, the chances of the table getting damp is extremely low. If the metal parts are made of uncoated mild steel and exposed to cold air then there is a small chance of surface rust, but as you’ve covered with it a duvet, the risk is minimal. The very cold frosty weather actually helps as this drops moisture out of the air and so lowers the relative humidity, and the water content of the air is low, around 3g per cubic metre.

To be scientific, if the current air temperature is 0C and Relative Humidity is 80% (it’s about that now), then - using a Physcometric Chart - the point at which condensation forms, the Dew Point, would be around -4C.

100 % agree except the relative humidity / absolute humidity typo.

Lambeth Cali · Dec 8, 2022

Ok thanks for all posts. I’m going to risk leaving it where it is.

Ch1pbutty · Dec 8, 2022

Don’t worry about it. It probably already been sat in a shipping container with for approx 30 days enroute from China, exposed to various temperature changes as it crossed the Pacific + Atlantic, and then sat in a warehouse in the UK before it got delivered to you.

G3WRT · Dec 10, 2022

yossarian said:
If you crack a window you should have zero condensation.

Yes I agree. Opening a window reduced 92% to 50% humidity.

Lambeth Cali · Dec 11, 2022

But it’s snowing!? I can’t bring myself to open a window. The vents will be open so air can move around.

GrahamB · Dec 11, 2022

What about running the parking heater a couple of times each day? Should help to drive out moisture and ventilate? Easy to do with the remote.

yossarian · Dec 11, 2022

GrahamB said:
What about running the parking heater a couple of times each day? Should help to drive out moisture and ventilate? Easy to do with the remote.

If your van contains 100g of water in its internal air before you switch on the heater and the heater operates on a closed loop then it will contain 100g of water after you run your heater.

The relative humidity may go down but air that stagnates against a cold surface has the same condensation potential.

GrahamB · Dec 11, 2022

yossarian said:
If your van contains 100g of water in its internal air before you switch on the heater and the heater operates on a closed loop then it will contain 100g of water after you run your heater.

The relative humidity may go down but air that stagnates against a cold surface has the same condensation potential.

Yes that makes sense, but is all the moisture actually sealed inside the van? I’m just speaking from experience of running my parking heater daily in this cold snap, simply for the pleasure of getting into a warm van. I’ve seen no sign of any condensation, even when it has cooled down again.

yossarian · Dec 11, 2022

If your van has no source of moisture (eg a person) inside and it exchanges air with the outside the humidity will be roughly equal inside and out. Condensation is likely to occur where localized air inside the van is cooled below its dew point.

This is unlikely to occur in a ventilated van. It would require large and rapid changes of temperature.

In an unventilated van the absolute humidity (and therefore the dew point) will remain pretty much constant (some moisture may be held in the furniture). Any air cooled below its dew point can cause condensation. Heating air will not alter its dew point.

The unknown is exactly how much air is exchanged in a sealed van. My guess is not much.

Some interesting numbers, very approximate and not exhaustively researched:

Air capacity + 10 deg C - 9g / cubic meter.
Rough van volume with roof down 10 cubic meters
Exhaled moisture per adult per hour: 10g

So hypothetically at 10 deg C and 70% humidity the van interior air will be saturated by 3 adults in an hour if not ventilated.