Tips for preventing condensation in a motorhome.

Gavin and Bigi

Gavin and Bigi

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This morning my campervan had loads of condensation in the windows. I'm sure there must be loads of ways of managing this. I don't store it with hook up so I can't run a dehumidifier. What else can I do?
 
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PP Bear said:
I keep mind locked tight, including all windows, then use this. Lots poo poo it, but had it now for 11 years and it’s brilliant. Some quote that in the last million years, they haven’t had a problem, but you have, so it’s my recommendation.

Wonder what an insurance company would say if they knew windows were left open, just a bit, but enough for anyone to get a long screwdriver or crowbar in, force it open and enter. Yep, they could do that with the windows tightly locked, but noisy, damaging and I don’t think any thief will want to drive with smashed windows.

Worth every penny and they also come scented, so van pongs nice too 👍🏻

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Have you a link to this?
 
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Having owned a river boat for many years, and trying a multitude of methods of reducing condensation/damp, the only thing that worked, and worked well, was to maximise ventilation. Trying to suck moisture out of the air is pointless unless the van is hermetically sealed, and trying to seal it completely will trap moisture. Take out the cushions and leave it. Unless it has holes in it, it will stay at ambient humidity.
 
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PP Bear said:
I keep mind locked tight, including all windows, then use this. Lots poo poo it, but had it now for 11 years and it’s brilliant. Some quote that in the last million years, they haven’t had a problem, but you have, so it’s my recommendation.

Wonder what an insurance company would say if they knew windows were left open, just a bit, but enough for anyone to get a long screwdriver or crowbar in, force it open and enter. Yep, they could do that with the windows tightly locked, but noisy, damaging and I don’t think any thief will want to drive with smashed windows.

Worth every penny and they also come scented, so van pongs nice too 👍🏻

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Is there a link for these and how many do you use
Thanks
 
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PP Bear said:
I keep mind locked tight, including all windows, then use this. Lots poo poo it, but had it now for 11 years and it’s brilliant. Some quote that in the last million years, they haven’t had a problem, but you have, so it’s my recommendation.

Wonder what an insurance company would say if they knew windows were left open, just a bit, but enough for anyone to get a long screwdriver or crowbar in, force it open and enter. Yep, they could do that with the windows tightly locked, but noisy, damaging and I don’t think any thief will want to drive with smashed windows.

Worth every penny and they also come scented, so van pongs nice too 👍🏻

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We have used one of these as well for about 10 years, never had any damp (touch wood). But remember to buy the refills in the beggining of the summer when they are on special as no one is using them then !!
 
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DWaldie said:
Having owned a river boat for many years, and trying a multitude of methods of reducing condensation/damp, the only thing that worked, and worked well, was to maximise ventilation. Trying to suck moisture out of the air is pointless unless the van is hermetically sealed, and trying to seal it completely will trap moisture. Take out the cushions and leave it. Unless it has holes in it, it will stay at ambient humidity.
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I quite agree. I have a boat and leave it fully vented, cupboards open. Just make sure that curtains aren't touching the windows.

I got a dehumidifier for home because my heating system said that 70% humidity was too damp. No 'damp spots' - I think it's just a 'damp house'.
I was away for 4wks and left the heating on very low (11°C). The humidity was 55% with the dehumidifier on but I switched that off because it does not drain itself. Whilst away the humidity dropped to 48%, to my surprise. I conclude that that was as much as the air at that time (November) could hold. Warmer can hold more moisture, so that's why it's higher when we're at home. The mission is to keep everything at the same temperature, to avoid cold spots. The more water the air can hold, the more there is to condense, so I don't see the need to keep things warm while absent. Save those pennies for when you need them.
 
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nicholsong said:
Kaercher window vacuum(re-chargeable) is your friend. There are others, but I do not know how good.

We even use it for washing and drying windows in the house.
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Great question
The guys saying they have no compensation are either very lucky or they just can’t see the condensation because it happens behind their covered walls and ceiling and absorbs into the insulation during the day.
We get condensation in our modern insulated double glazed, well ventilated house, so how you can avoid it in a motorhome is beyond me.

I bought 2 MB sprinters and have converted one.
Every morning, there is water falling off the ceilings of the metal panels.
I have looked into it extensively and have personally come to the conclusion that you can not fight condensation fully. There are obviously things you can do with insulation to reduce condensation but as previous members have said, if you produce moisture from showering or cooking, it has to go somewhere and the temperature difference overnight produces moisture from the air. It is basic physics.

Some people sing the virtues of a moisture barrier and others say they do not work, so who do you believe?

One of the best solutions I saw on a YouTube clip was a couple who used external covers for their windows except the main windscreen which gave the moisture in the air a surface to condense, and then just use a karcher battery operated window cleaner to clear that water from one surface rather than all of them.

Love to hear of other successes. And very happy to be wrong.
 
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Ducatian said:
We've used the Karcher Vac since day one, however since fitting the expernal reflective Windscrren/Side side window cover, the problem as all but gone away. Keeps the ice off too :)
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Very interesting thank you 👍
Are you certain that you are not just moving the problem or part of the problem from windows you can wipe, to surfaces you can not see?
I am not suggesting for one minute that is the case but surely the insulated walls still condense the moisture that is inside the van?
I may be completely wrong but I too am trying to understand it better.
 
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Gyro said:
Why then condensation on the outside of our double glazing when toasty inside? (Rhetorical)
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Because it's colder inside and warmer outside. FACT!
garymumford said:
Great question
The guys saying they have no compensation are either very lucky or they just can’t see the condensation because it happens behind their covered walls and ceiling and absorbs into the insulation during the day.
We get condensation in our modern insulated double glazed, well ventilated house, so how you can avoid it in a motorhome is beyond me.

I bought 2 MB sprinters and have converted one.
Every morning, there is water falling off the ceilings of the metal panels.
I have looked into it extensively and have personally come to the conclusion that you can not fight condensation fully. There are obviously things you can do with insulation to reduce condensation but as previous members have said, if you produce moisture from showering or cooking, it has to go somewhere and the temperature difference overnight produces moisture from the air. It is basic physics.

Some people sing the virtues of a moisture barrier and others say they do not work, so who do you believe?

One of the best solutions I saw on a YouTube clip was a couple who used external covers for their windows except the main windscreen which gave the moisture in the air a surface to condense, and then just use a karcher battery operated window cleaner to clear that water from one surface rather than all of them.

Love to hear of other successes. And very happy to be wrong.
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Ventilation and warmth IS THE SOLUTION.
 
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If you don't allow ventilation, all the moisture from cooking and breathing will be trapped inside and build up. Eventually the air will become saturated and unable to hold any more. That’s when condensation will start to form and it will do so most readily on the coldest surfaces. Those surfaces will be the windscreen, which is always single-glazed, and any thermal bridges. A thermal bridge is where there is less or no insulation between you and the outside (like a window frame).

Overnight, the air inside cools (unless you keep the heating on full-blast) and is unable to hold as much vapour, which must go somewhere. You will also (hopefully) continue to breath, so vapour levels may continue to be high at a time when the air is cooling and is less able to hold it. This is when ventilation helps, by allowing ‘damp’ air to escape into the atmosphere and letting comparatively ‘drier’ air replace it.

If you can stop the air from becoming saturated, you won’t get condensation.

Allowing the windscreen to condense any excess moisture may not be a bad idea. It’s a large area and away from soft furnishings, which you don’t want to get damp, and it’s relatively easy to dry in the morning. That’s much better than having to mop-up in multiple smaller places around the van.

Ventilation will reduce the chance of condensation, as will keeping the fabric of the van warm. Cooling air and cold surfaces are difficult to avoid, though.

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two said:
If you don't allow ventilation, all the moisture from cooking and breathing will be trapped inside and build up. Eventually the air will become saturated and unable to hold any more. That’s when condensation will start to form and it will do so most readily on the coldest surfaces. Those surfaces will be the windscreen, which is always single-glazed, and any thermal bridges. A thermal bridge is where there is less or no insulation between you and the outside (like a window frame).

Overnight, the air inside cools (unless you keep the heating on full-blast) and is unable to hold as much vapour, which must go somewhere. You will also (hopefully) continue to breath, so vapour levels may continue to be high at a time when the air is cooling and is less able to hold it. This is when ventilation helps, by allowing ‘damp’ air to escape into the atmosphere and letting comparatively ‘drier’ air replace it.

If you can stop the air from becoming saturated, you won’t get condensation.

Allowing the windscreen to condense any excess moisture may not be a bad idea. It’s a large area and away from soft furnishings, which you don’t want to get damp, and it’s relatively easy to dry in the morning. That’s much better than having to mop-up in multiple smaller places around the van.

Ventilation will reduce the chance of condensation, as will keeping the fabric of the van warm. Cooling air and cold surfaces are difficult to avoid, though.
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You do not need heating on at full blast but above dewpoint. Therefore 10 degs if usually more than enough. Just keep your roof vents open a bit and your fixed vents unblocked with a screen cover and you should have no problems. Been doing this for over 40 years a NOT A SINGLE DAMP ISSUE.... Sometimes minor condensation but only once in a blue moon.
THERE IS NO SECRET OR MAGIC - JUST FACTS.
 
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Petroleumblownapart said:
You do not need heating on at full blast but above dewpoint. Therefore 10 degs if usually more than enough. Just keep your roof vents open a bit and your fixed vents unblocked with a screen cover and you should have no problems. Been doing this for over 40 years a NOT A SINGLE DAMP ISSUE.... Sometimes minor condensation but only once in a blue moon.
THERE IS NO SECRET OR MAGIC - JUST FACTS.
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10deg is uncomfortably cold in the evening if you're in the van so how do you reduce condensation without ventilating away all that hot air that's cost you a fortune in gas or leccy
 
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dunnah01 said:
10deg is uncomfortably cold in the evening if you're in the van so how do you reduce condensation without ventilating away all that hot air that's cost you a fortune in gas or leccy
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10 degrees when asleep not in the evening for goodness sake. Ventilation at low constant level dries the air and actually let's you feel warmer than damp, miserable air.
YOU CANT ESCAPE PHYSICS or do things differently and expect PHYSICS to bend to your will.
Sorry but this is FACT.
 
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Petroleumblownapart said:
10 degrees when asleep not in the evening for goodness sake. Ventilation at low constant level dries the air and actually let's you feel warmer than damp, miserable air.
YOU CANT ESCAPE PHYSICS or do things differently and expect PHYSICS to bend to your will.
Sorry but this is FACT.
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Very interesting and very important to acquire a good grasp of what is and isn’t possible.
It seems there is a lot to learn and the guys who have experience find ways to manage the inevitable condensation.
Heating and ventilation seem to be the main thread - which makes sense.
It strikes me that if you don’t try to manage it, and pretend that it doesn’t occur just because you can’t see it, you might be storing up problems for the kit in your van over time?
I am very much at the bottom of the condensation learning curve, but enjoying the journey.👍
 
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Petroleumblownapart said:
10 degrees when asleep not in the evening for goodness sake. Ventilation at low constant level dries the air and actually let's you feel warmer than damp, miserable air.
YOU CANT ESCAPE PHYSICS or do things differently and expect PHYSICS to bend to your will.
Sorry but this is FACT.
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I think what you're trying to shout is that you don't know how to avoid condensation when using the van in colder evenings.

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garymumford said:
I am not suggesting for one minute that is the case but surely the insulated walls still condense the moisture that is inside the van?
Click to expand...

No, if they are above the dew point there will be no condensation. The front windscreen is uninsulated and hence provides a mechanism for condensation to occur.

Petroleumblownapart said:
You do not need heating on at full blast but above dewpoint.
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Agreed.

Ian
 
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garymumford said:
Very interesting thank you 👍
Are you certain that you are not just moving the problem or part of the problem from windows you can wipe, to surfaces you can not see?
I am not suggesting for one minute that is the case but surely the insulated walls still condense the moisture that is inside the van?
I may be completely wrong but I too am trying to understand it better.
Click to expand...
The expernal reflective Windscreen/Side side window cover, is on the outside of the vehicle, so from the inside, I can clearly see the inside of the Windscreen
 
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garymumford said:
Very interesting and very important to acquire a good grasp of what is and isn’t possible.
It seems there is a lot to learn and the guys who have experience find ways to manage the inevitable condensation.
Heating and ventilation seem to be the main thread - which makes sense.
It strikes me that if you don’t try to manage it, and pretend that it doesn’t occur just because you can’t see it, you might be storing up problems for the kit in your van over time?
I am very much at the bottom of the condensation learning curve, but enjoying the journey.👍
Click to expand...
you are not at the bottom or otherwise you would hate it

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If the weather is not warm and we are using the van we expect some condensation on the windscreen which is easily removed. In effect the cold windscreen is acting as a free dehumidifier thus protecting against condensation elsewhere. This is one reason I dislike external screens as they reduce this effect. When the van is not in use the maxxfan vent is open and no condensation as there is nothing to produce it.
 
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Gavin and Bigi said:
I have been in the van during the day as we are renovating it and painting it. The heating has been on.
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Heating on gas? Gas burning creates moisture & so does your body. When you finish for the day leave the door open and have a beer before going home. That way most of the moisture will evaporate before locking up.
 
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Jonno1103 said:
Heating on gas? Gas burning creates moisture & so does your body. When you finish for the day leave the door open and have a beer before going home. That way most of the moisture will evaporate before locking up.
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The heater has a balanced flue so that can't happen.
 
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Gavin and Bigi said:
This morning my campervan had loads of condensation in the windows. I'm sure there must be loads of ways of managing this. I don't store it with hook up so I can't run a dehumidifier. What else can I do?
Click to expand...

Gavin and Bigi said:
This morning my campervan had loads of condensation in the windows. I'm sure there must be loads of ways of managing this. I don't store it with hook up so I can't run a dehumidifier. What else can I do?
Click to expand...
 
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Thanks to everyone I have a little water ingress in rear corner of my awaiting repair just wondering what dehumidifier to use but seems I am using the one you are all suggesting so thanks I will continue 😊 using the unibond.

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During the whole of 2023, this thread talked about removing the symptoms of condensation.

Finally, we have a post which adresses the real issue - water ingress.

It can be as simple as people coming in out of heavy rain, or it can be a leak.

Either way the cause of the water ingress has to dealt with. It is no good just hiding the symptoms.
 
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