Removing damp inside caravan

Given all the fixed ventilation required in caravans by law there's a constant throughput of ambient air in the caravan - so running a dehumidifier in a constant supply of moist fresh air is pointless.

.......it is a very good thing to do if the Relative Humidity is low  (below 50%)

I have a weather station and it tells me what the Relative Humidity of the air is inside my house and outside.

On a day like today it is reading 41% inside (heated) and 46% outside at the time of this post.

My caravan is stored next to my house so I have been out to switch on the high level 12 volt extractor fan.

All opening vents are shut as air comes in through the fixed vents mostly at floor level.

I agree with Roger

Because of the vents in a caravan, by using a dehumidifier you are just pulling more moist air into the van.

The same goes for using crystals & salt. A waste of time & money

Actually i don"t think it is a waste of time and money  ( Crystals &  Salt )    

Since we brought our brand new caravan we have always put Crystals &  Salt in through the winter months and we also have a Breathable caravan cover on,  The Crystals we use lasts up to three months and so far they have been great. 

Hello Beachball,

My own professional opinion is that in a stored caravan and provided the caravan does not suffer from any water ingress problems then there is sufficient air exchange with the outside to render any dehumidification process ineffective, and thus using any form of dehumidification  has no practical value. 

Because of the amount of ventilation built into all caravans, you will find that dehumidifiers (of any sort) will collect moisture, but it is from the air passing passing through not from the structure or materials of the caravan.

As you have always used crystals and salt, you have no basis on which you can logically arrive at your contention. You can only make a valued conclusion if you have tried NOT using crystals and salt and found a difference.

I would venture to suggest that if you did find any difference, then you should be looking for water ingress. 

John is too diplomatic - if damp is a problem in a caravan, it's leaking somewhere - natural moisture doesn't give a problem as caravans are ventilated. The caravan industry has perpetuated myths about needing to use dehumidifiers or hygroscopic crystals to absorb water to save itself the cost of repairing caravans under warranty.

All air has some natural moisture in it but the amount varies dramatically - but dehumidifiers/crystals will aLWAYS take some water out, only to find mother nature replacing it!

NOW is the time to air all the caravans in winter storage because the persistent cold temperatures have brought very low humidity, at around 10-20% RHI - which is way below the comfort level settings on any humidifier systems. It's also a good time to open the plugs in double glazing IF misting is a problem, let it fill with relatively dry air for a couple of days and then replug them.

Talking of window plugs what is the best way to remove them? Ken

Ive used two of the crystal type in my van and it collects a fair amount of moisture in the collection tray.

Year before last I didnt use them and found that there were "mouldy" patches appearing on various parts of the wooden units.

Used them last year, and had none of the "mould" problems.

Will continue to use them.

Hello GeorgeandAde, 

Given the details of your report, then it suggests that you may have a damp problem with water ingress somewhere.

Hi Prof.

I hope I havent and the last service in October at local Bailey dealer didnt show up any problems.

By "Mould",I would say its a powdery substance mainly towards the bottoms of a few units which readily wipes off with a damp cloth,but will keep my eye on it.