# Condensation in storage - help!



## Jagman (Feb 16, 2008)

Hi All

I'm getting internal condensation in storage, never really noticed this before, no leaks and hab. check showed no damp probs., not on hook up so........

Can anyone recommend a 'passive' dehumidifier that they have used to their satisfaction? I use the van every fortnight at least so dehumidifier could be 'seen to' at that frequency if necessary.

Thanks

Jagman


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## spindrifter (Nov 14, 2006)

Hi Jagman

There are many de-humidifiers on the market - do a Google search.

The cheapest way is to obtain a shallow tray or two (cat litter tray is ideal) and fill with rock salt (cheap from supermarkets etc) put trays on motorhome floor on some newspaper. When salt is damp stick it in the oven at home (on an appropriate metal tray) and dry it out and re-use - or chuck it away and replenish with fresh salt.

Hope that helps. Many more solutions will follow by other members I'm sure. Good luck.

Cheers

David


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## Jagman (Feb 16, 2008)

Thanks David, I did the google thing I just wondered which one's mhing colleagues would recommend from experience,

The salt idea is excellent. I wonder if having salt around is somehow likely to lead to corrosion problems, not if it is confined to the trays of course but I suppose there is a risk of spillage due to clumsiness etc.

Thanks for the idea!


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## spindrifter (Nov 14, 2006)

An idea I heard about was to put the salt in a polythene or plastic bag put a number of holes in the bag (facing up of course) and then put in the tray with a good spread of newspaper on the floor. Any probs re: corrosion would then be virtually nil.

Cheers

David


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## Jagman (Feb 16, 2008)

Thanks for additional info. David, much appreciated

Jagman


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## 96299 (Sep 15, 2005)

Hi Jagman

I have posted on these before and this is what I use..... Air Dry Bags I have three in my burtsner argos and dont have any problems at all.

Steve


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## Jagman (Feb 16, 2008)

Many thanks Steve, I did my best to search the data base of previous postings and read loads but missed yours so cheers for naming a product which you've actually used - best sort of recommendation!

Jagman


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## Grizzly (May 9, 2005)

Jagman said:


> I'm getting internal condensation in storage, never really noticed this before, no leaks and hab. check showed no damp probs., not on hook up so........


Have you checked that you have sufficient ventilation - all lockers and internal doors open and not covered by upholstery ? Are all your air vents open - has a previous owner blocked anything for draft prevention ? Are the roof vents ( ie around the Heki roof lights) clean and the minute holes not blocked by dust ?  Do you "air" the van before you leave it- ie open the doors and windows and let cool fresh air blow through ? Is there a source of water in the van- when you left the van did you wipe down the fridge or did any of the defrosting water run behind the fridge and stay there ? Does the van smell damp - or simply cold as it should ?

We've never had condensation problems in any of our vans and have never put in heating or dehumidifiers. I'd want to know why there was condensation before I took any measures.

If you have serious problems then the salt will only absorb a little of the water and not properly address the high humidity unless you are prepared to go in every day and renew or dry it.

G


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## sideways (Jun 2, 2008)

Go to Spain for the winter that will cure it.Sorry couldnt resist that. Seriously ventilation is the best cure not always easy to achieve though. Which surfaces are you getting it on.?


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## Jagman (Feb 16, 2008)

Thanks for the thoughts G, I did checks vents when I got the van and get the hab. check guy to double check when he does the service, and everything seems OK in that respect. 

I think the fact that I've only just noticed this problem after almost three years of all-year-round use with max. lay-up of two weeks (very occasionally three) in storage after which there would be at least a day out in it with approx 120 mile trip suggests that it could be due to particular atmospherics. These may not occur very often - particular combinations of temperature and humidity fluctuation perhaps - but I want some defence against it. As yet there is no musty smell and no sign of mould. 

My concern was that last week for the very first time I went into the van and was able literally to wipe moisture off all the hard surfaces: worktops, cupboard doors, oven hob cover, oven door, etc., so either:

1. Something different had happened
2. It had happened before but cleared up before I returned to the van

Reading through the archives its is obviously a fairly common problem and there are many comments about ventilation and also, interestingly, warnings about dehumidifying too much which might result in wood cracking and floors lifting!

I found the two suggestions re. passive absorbents most useful and will pursue both avenues, I am also aware that Amazon, amongst others, offer a pair of units for about £20 which operate without power whilst absorbing and when 'full' can be dried out by plugging into the mains for 8 hours or so. Ideal for swapping perhaps on a weekly or fortnightly basis.

After a period of interesting experimentation it will either be salt or a slightly more complicated bit of kit!!

Thanks again for your comments

Jagman


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## Jagman (Feb 16, 2008)

Thanks for your interest sideways, my last post mentions surfaces, I was doing it as your post arrived!


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## Grizzly (May 9, 2005)

Jagman said:


> My concern was that last week for the very first time I went into the van and was able literally to wipe moisture off all the hard surfaces: worktops, cupboard doors, oven hob cover, oven door, etc., so either:


Hmm ! That is worrying. When you'd dried off the surfaces and aired the van did it happen again ?

G


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## Codfinger (Jan 11, 2008)

*damp*

We have been using a small dehumidifier during all this wet weather (our van lives outside) and does catch some weather, however normally this is not needed.
Its quite suprising how quickly the tank fills !


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## jaks (Sep 20, 2006)

*condensation*

Hi for years we have had caravans tourers and statics and all we have ever done is made sure all vents are clear no upholstery or cushions against walls and i use glass storage jars or glass plant pots etc and put in common cooking salt it cost something like 57p a kilo around the m/h and it works a treat hope this helps just make sure you dont put salt in anything that could corode and leak and keep away from your lovely worktops JAKS


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## Jagman (Feb 16, 2008)

Thanks for that codfinger - what sort of dehumidifier is it?

Thanks for the idea jaks; jars and pots seem like a good way to keep the salt under control  

Thanks again G. It was OK the following day but I've not seen it for about week now but will pop up tomorrow or Sunday and report back.

Jagman


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## Jezport (Jun 19, 2008)

May be just a case of the van is closed and cold, when you open it up the warmer more humid air hits the cold surfaces and condenses on contact.


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## Grizzly (May 9, 2005)

*Re: condensation*



jaks said:


> Hi for years we have had caravans tourers and statics and all we have ever done is made sure all vents are clear no upholstery or cushions against walls and i use glass storage jars or glass plant pots etc and put in common cooking salt it cost something like 57p a kilo around the m/h and it works a treat hope this helps just make sure you dont put salt in anything that could corode and leak and keep away from your lovely worktops JAKS


Ah but have you tried not using any salt and do you get condensation ?

It's like the elephants and the torn up paper again...

G


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## TR5 (Jun 6, 2007)

Hi Jagman

Assuming you have no water ingress problems, salt is just fine to reduce the humidity in the van. If you live in a hard water area you may find a neighbour with a salt softener. Partly fill a washing up bowl with softener salt, which you can then give back to the neighbour to add to his softener, after use. The salt being damp will not reduce it's efficiency in the softener, as it has to dissolve anyway.

Maybe go halves with the cost of the salt - saves you money, keeps neighbour happy, and keeps van dry - like 3-in-1 :lol: 

However, if you have a damp problem, then reducing the humidity in the atmosphere within the van by any means, will only encourage (draw) more damp in through wherever it is seeping!

Good luck!


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## Hub (Sep 12, 2005)

spindrifter said:


> Hi Jagman
> 
> There are many de-humidifiers on the market - do a Google search.
> 
> ...


Hi everyone,
Its the cheap 'rock salt' aspect of this thread that got me thinking (careful......)!
Whilst in Spain we bought a big gas plancha and the way we like to cook whole fish is on a bed of rock salt about an inch thick.
20 kilos of rock salt in Spain is 3€. Half a kilo in UK supermarkets is about £1-50/£2-00. We did bring back a big sack of salt with us but we've used it all up.
Does anyone know where to buy cheap rock salt in UK? Using about 1+1/2 kilos at a time is working out pretty expensive. Sometimes it costs more for the salt than the fish. Crazy!
And does anyone know why its so dear? Does anyone know anything about the vagaries of the global rock salt market?

Thnx in advance. Any help much appreciated.
Hub


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## Jagman (Feb 16, 2008)

Thanks for recent replies and what might become a hijack  

TR5 - no water ingress as far as I can tell, recent hab. check OK too - no damp. I'm not in hard water area so cannot develop your double whammy idea  

Jezport - I agree that something like that could be the cause, 'freeky atmospherics' which would explain why I haven't noticed it every time I return to the van

Hub - I scent a whiff of hijack  - can't help with global NaCl situation but live quite near Cheshire salt mines so will investigate next time I'm on a run in that direction; this will probably involve forcing myself into local pubs to quiz locals - tough work but someone will have to do it.

G - I'll check for elephants as soon as I get up to the van later this morning

Have a good day everyone  

Jagman


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## Grizzly (May 9, 2005)

Just a thought...given that good ventilation is necessary for preventing condensation I wonder if a solar powered fan would stir up the internal air and prevent condensation ?

There are plenty of these on the market- intended for conservatories, cars, boats, greenhouses and the like and usually for summer use - see Maplins for example. 

In winter they would not get enough solar energy to work every day ( given that the solar panel would have to be internal and somewhere like the dashboard or hung from the rooflight) but that would not be too important.

An additional bonus is that the fan is available for you to take away and use in summer to keep you cool.

G


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## Jagman (Feb 16, 2008)

Thanks for that G., never even thought of it, I'll investigate in reality today if the run out takes me near a Maplins, if not I'll do it virtually later on.

The idea of the fan being both self-regulating and independent of the van's electrics is very attractive.


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## sallytrafic (Jan 17, 2006)

I don't know if this helps but is a quote from me 2 years ago I stand by it but have replaced the chemical dehumidifier with a wee electric one from B&Q.



sallytrafic said:


> Mould is a killer (some times literally) but mainly it is the devil to shift so its always better never to get it. What you need to grow mould is a little surface moisture. Warm moist air meeting a cold surface is way of rapidly acquiring surface moisture. So how best to avoid mould?
> 
> Two methods remove the moisture or make the surfaces warm compared to the air. The latter is very difficult to acheive with small heaters or big spaces because what tends to happen is you raise the temperature of the air first which makes it capable of carrying more moisture which if it then finds a coldspot rapidly dumps the moisture on the cold surface.
> 
> ...


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## Jagman (Feb 16, 2008)

Thanks for the link Frank, I agree that the real 'fear' is mould, especially if it gets established in soft furnishings, head-linings etc. Could you recommend any particular chemical type dehumidifier or elaborate upon your pre-electric strategy a little?

Cheers


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## safariboy (May 1, 2005)

Jagman said:


> Thanks for the link Frank, I agree that the real 'fear' is mould, especially if it gets established in soft furnishings, head-linings etc. Could you recommend any particular chemical type dehumidifier or elaborate upon your pre-electric strategy a little?
> 
> Cheers


Calcium chloride is probably the most practical. Available as a drying agent from builders' merchants DIY etc. Salt (Sodium chloride) is much less effective.


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## Jagman (Feb 16, 2008)

Thanks safariboy, I'll get some to try. I think its going to be a combination of things including a passive absorbing system (ie storage jars with stuff in!).

Incidentally, just picked the van up, its been standing for a wet week, its cold today and its not wet inside at all, no condensation. I'm thinking its related to atmospherics and for whatever reason today doesn't tick the boxes. 

Jagman


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## safariboy (May 1, 2005)

For condensation to take place warmer wet air must meet a colder surface. Anti-condensation pain works by absorbing the water.
So if the temperature of the van drops a lot as it can at this time of year condensation is likely; especially if you have just been using the van and making the air damp. Once you have dried off the air it should be OK


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## Terryg (Jun 18, 2009)

Hi all,

I am trying salt at the moment, thanks to this thread and Davids input. However in the past I worked on industrial Air dryers, these used a product called Silica Gel. It will absorb 35% of its weight in water, once used heat to reactivate the Silica Gel. This product is inert so no corrosion problems. I have found it available on-line in 500g bags or larger containers, once I get the best price I will try it.

3Kg of Silica Gel will absorb 1 Litre of water, only problem is more expensive than salt.

Silica Gel Info

Terry


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## sallytrafic (Jan 17, 2006)

Jagman said:


> Thanks for the link Frank, I agree that the real 'fear' is mould, especially if it gets established in soft furnishings, head-linings etc. Could you recommend any particular chemical type dehumidifier or elaborate upon your pre-electric strategy a little?
> 
> Cheers


Calcium chloride in plastic boxes, The Calcium Chloride absorbs the water from the air then dissolves as it continues to absorb its is not practicably renewable.


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## Spacerunner (Mar 18, 2006)

Condensation scenario.

Motorhome left for two weeks. Its well insulated but gradually cools right down. Outside day temperatures cannot make headway against the van's insulation.

You go to 'van on a relatively warm day and open the door. Warm moist air rushes in, hits very cold surfaces and all the moisture in the newly introduced air condenses out almost instantaneously on any cold surface.

What you don't see is the condensation on soft furnishings, this is where the real danger lies. And the reason its recommended to remove soft furnishings when the van is not being used in the winter.

Without mains electric I'm not sure how you could prevent the problem except for increased ventilation to equalise the interior and exterior temperatures and moisture content.


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## Codfinger (Jan 11, 2008)

*Damp*



Jagman said:


> Thanks for that codfinger - what sort of dehumidifier is it?
> 
> Jagman


When it stops raining I will pop out to van and have a look for you!


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## Codfinger (Jan 11, 2008)

*damp*

Ok so we use one of these http://www.breathingspace.co.uk/pages/widetechwdh210hb.php


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## DustyR (Jan 26, 2009)

*Damp & Condensation*

I have read all these suggestions but one thing puzzels me, what do MH dealers do with all those vans parked outside during the winter months, I cant see them running heaters, de-humidifiers etc. Come to think of it we bought our MH during January but fortunately have not found any trace of mould or damp.


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## Codfinger (Jan 11, 2008)

*Damp*

A valid point Dusty, but our previous camper used to sweat a lot so for peace of mind we use a dehumidifier, you should see how much water it collects 8O


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## Jagman (Feb 16, 2008)

Thanks for that codfinger, hope you didn't get too wet  As I'm not on hook-up in storage I'm going to try a passive system.

Spent the day running round various places in the North West and decided to try the *'Kontrol Streamline Moisture Trap'* which cost me £5.99 per unit. Its a plastic box with a calcium chloride 'charge'. You rig it up (very easily) so that the box divides itself into an upper 'tray' containing the chemical and a lower 'tray' to collect the water. I got three, two for the van, which I've now installed, and one for a car on the drive which we don't use much and which can suffer from condensation ('steamed-up' windows) on cold mornings. The idea being that I will monitor the one in the car every day so that I can get some sort of indication how the two in the van are coping. The lower tray in the 'trap' will eventually fill with water according to the instructions, so I need some indication as to when to go up to the van to empty them; hopefully the one in the car outside the front door should give me that indication.

I also bought a 2.5kg pack of CaCl (branded by the same outfit: Kontrol) which will hopefully provide two refills for the three traps and thereby allow the experiment to run through to spring providing there isn't so much moisture that the traps last much less than the 2 months advertised :?

For this cost I could have got a pair of the plug-in-the-mains-to-recharge type units but they seemed a bit small.

Let the experiment commence 

Good question about vans in dealers DustyR!

Jagman


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## Jezport (Jun 19, 2008)

Jagman said:


> Thanks for that codfinger, hope you didn't get too wet  As I'm not on hook-up in storage I'm going to try a passive system.
> 
> Spent the day running round various places in the North West and decided to try the *'Kontrol Streamline Moisture Trap'* which cost me £5.99 per unit. Its a plastic box with a calcium chloride 'charge'. You rig it up (very easily) so that the box divides itself into an upper 'tray' containing the chemical and a lower 'tray' to collect the water. I got three, two for the van, which I've now installed, and one for a car on the drive which we don't use much and which can suffer from condensation ('steamed-up' windows) on cold mornings. The idea being that I will monitor the one in the car every day so that I can get some sort of indication how the two in the van are coping. The lower tray in the 'trap' will eventually fill with water according to the instructions, so I need some indication as to when to go up to the van to empty them; hopefully the one in the car outside the front door should give me that indication.
> 
> ...


I use one of these in my fridge at home, it works well.


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## safariboy (May 1, 2005)

*Re: Damp & Condensation*



DustyR said:


> I have read all these suggestions but one thing puzzels me, what do MH dealers do with all those vans parked outside during the winter months, I cant see them running heaters, de-humidifiers etc. Come to think of it we bought our MH during January but fortunately have not found any trace of mould or damp.


If the van is unoccupied and starts off reasonably dry there should not be a problem. The vans are not heated and people will only be in them for a short period so little water vapour is added to the air. The air circulation will probably deal with this.
In your van you will have been cooking and giving off water yourself. If you have some heat in the van - no problem but when you come home the van will be warm and the air quite damp. Now it cools down and you get condensation. 
The following might help:
(1) When cooking or boiling water make sure that there is through venting. At least two windows open.
(2) When driving home have as much air as possible.

If this does not help there must be a source of water vapour.

Hope that this helps.

best Wishes,

Safariboy


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