Windscreen Condensation

View previous topic View next topic Go down

Windscreen Condensation

Post by Gram on Sun Feb 23, 2014 7:27 am

Two or three times this winter I have noticed condensation on the inside of the windscreen of my Symbol.

Is this normal?  Is it more likely to occur in a van conversion than a coachbuilt?

G
avatar
Gram
Member
Member

Male

Posts : 253
Joined : 2013-02-21
Member Age : 73
Location : Hants
Auto-Sleeper : Symbol
Vehicle Year : 2009

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Spospe on Sun Feb 23, 2014 8:21 am

Assuming you mean that the condensation is there when you are stopped on site, then yes it is completely normal in cold weather to see condensation on the inside of the cab windows.

Closing either, or both, curtains and or blinds, or using internal screens will have very little effect and the only system which will offer a more or less complete solution is to fit external screens. In very cold weather I have had the experience that the external screens prevented all condensation, but when taking them off in order to drive away, the screen became covered in condensation before the heater warmed up!

To answer your second question, the smaller the internal volume, the greater the chance of condensation due to the ratio of surface area of glass to internal volume of air.
avatar
Spospe
Donator
Donator

Male

Posts : 787
Joined : 2013-11-18
Member Age : 73
Location : South Manchester
Auto-Sleeper : Warwick Duo
Vehicle Year : 2014

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Gram on Sun Feb 23, 2014 8:57 am

Thanks, Spospe.

Sorry, I didn't explain myself fully.

The van has been laid up on my drive all winter.

No heating or dehumidifier in operation.  Water system fully drained.

G
avatar
Gram
Member
Member

Male

Posts : 253
Joined : 2013-02-21
Member Age : 73
Location : Hants
Auto-Sleeper : Symbol
Vehicle Year : 2009

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Dutto on Sun Feb 23, 2014 10:55 am

Hi there,

Whenever this happens we stick on a 700 watt Dimplex Chico for about two hours each night until the condensation doesn't appear.

Hope this helps.  allthumbz 

Best regards,
 drinksallround

_________________
Dutto - Living more in hope than expectation; and seldom disappointed!
avatar
Dutto
Donator
Donator

Male

Posts : 7866
Joined : 2011-06-15
Location : Lincolnshire
Auto-Sleeper : Duetto

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Gram on Sun Feb 23, 2014 9:31 pm

Thanks, Dutto - so it does happen to other people.

I'm wondering whether it is due to

a) water laying in the vehicle somewhere causing the humidity to stay high (I hope not!)

or

b) a sudden drop in outside temperature after a period of high humidity.

The concern is, if it's condensing on the windscreen then where else is it condensing and how long will it take to clear?

G
avatar
Gram
Member
Member

Male

Posts : 253
Joined : 2013-02-21
Member Age : 73
Location : Hants
Auto-Sleeper : Symbol
Vehicle Year : 2009

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by nimbus on Sun Feb 23, 2014 11:08 pm

It happens very occasionally in our Warwick Duo when laid up. Usually happens late evening and it disappears next morning. The van feels dry inside although I sometimes leave a heater on for a few hours.

nimbus
Member
Member

Male

Posts : 220
Joined : 2011-03-08
Member Age : 76
Location : Bristol
Auto-Sleeper : Warwick Duo

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by peugeotboxer on Sun Feb 23, 2014 11:22 pm

Happens on mine as well. Usually after any 'sunshine'   hugegrins during the day!! Then cold at night. Screen condensed next day.

PB
avatar
peugeotboxer
Donator
Donator

Male

Posts : 2640
Joined : 2011-06-24
Location : Somerset
Auto-Sleeper : Harmony
Vehicle Year : 2000

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Stewart John on Mon Feb 24, 2014 3:21 am

Hi

I have had condensation on the windscreen other years but this year have not seen any being a warm winter. But having said that this winter I left the air blowers vents open with the air coming in from the outside onto the windscreen. So that may have helped to keep it clear.   up!

_________________
Stewart
avatar
Stewart John
Member
Member

Male

Posts : 283
Joined : 2012-01-15
Member Age : 69
Location : Loughborough
Auto-Sleeper : Topaz 2.0 2014

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Spospe on Mon Feb 24, 2014 6:21 am

Gram

I have never, (in 13 years) had condensation in the manner you describe. The van when not in use is parked facing due north-south, with the cab facing north. I suspect that, in part at least your condensation could be caused by the sun heating the cab area. Can you say what was the orientation when you had the condensation?

If the sun is hitting the cab (and mine never gets the sun directly on the windscreen), then that is I suspect, the root cause of your problem.

Leaving the cab ventilation set so that any draughts play on the screen and not blocking-off any fixed ventilation will help. I have never, ever used either a dehumidifier or a heater in any caravan or motorvan since 1977 and never, ever had a problem with condensation (all vehicles faced due north-south and all have been in the Manchester area, so well away from the sea).
avatar
Spospe
Donator
Donator

Male

Posts : 787
Joined : 2013-11-18
Member Age : 73
Location : South Manchester
Auto-Sleeper : Warwick Duo
Vehicle Year : 2014

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Gram on Mon Feb 24, 2014 6:32 am

Yes, Spospe, my cab faces south-east so does get some sun on the windscreen - generally, in the winter, only first thing in the morning.

Maybe I should keep the screen covered, do you think?

G
avatar
Gram
Member
Member

Male

Posts : 253
Joined : 2013-02-21
Member Age : 73
Location : Hants
Auto-Sleeper : Symbol
Vehicle Year : 2009

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Dutto on Mon Feb 24, 2014 8:59 am

Hi there,

"No." to covering the screen.

Condensation is to be expected on any cold surface at any time of the year.

Dew starts falling at night (actually it usually starts well before dusk) and whether it becomes "dew" or "frost" there is almost never a night when it doesn't occur.

Inside the van whenever the internal temperature falls below the "dew point" the moisture in the air will condense out as water on the coldest surface; and this is most often the glass windscreen.

The term used is "relative humidity" for the simple reason that the moisture contained in the air is dependent on the temperature of the air.

Higher temperatures can hold more moisture and cold air can hold less; hence the "dew" that appears when the air cools down at night.

Let's assume that the "relative humidity" is at 85% in the evening when the air temperature is at 15 degrees.

As the temperature drops the "relative humidity" will start to rise and at say 8 degrees it may have risen to 95%.  At this stage there will be no moisture condensing out as water on the upholstery, work-surfaces or the windscreen.

Assume that the outside temperature keeps falling and reaches 4 degrees.  Inside the van the temperature will fall quickest at the windscreen and the air nearest the windscreen will cool to 4 degrees almost immediately.  At this stage the "relative humidity" near the windscreen will be at 100% and water will start to condense on to the glass.

The condensation process on the windscreen actually reduces the "relative humidity" of the rest of the air in the van so even though the temperature inside the van may finally reach 4 degrees the moisture condensing out on the windscreen will maintain the "relative humidity" of the air within the van at less than 100%.  This may result in a situation where the windscreen is covered in condensation but no water condenses out on work-surfaces and the upholstery doesn't become 'damp".

When you introduce a small heater into the van the temperature stays above the "dew point" temperature, the air touching the windscreen doesn't reach 100% "relative humidity" and water doesn't condense on the windscreen.  (Actually, it does sometimes condense but it evaporates just a quickly so it isn't seen.)

With regard to the positioning of the van the front windscreen introduces a lot more heat into the van's atmosphere if it is facing south rather than if it is facing in any other direction.  The warm air in the van during the day means that the air in the van can hold more moisture than if it was cold and therefore there is more water available to condense when the windscreen cools down at night.

This is why I recommend that the heater is switched on ONLY during the night; in an attempt to keep the temperature as stable as possible.

Hope this helps.  allthumbz 

Best regards,
 drinksallround

_________________
Dutto - Living more in hope than expectation; and seldom disappointed!
avatar
Dutto
Donator
Donator

Male

Posts : 7866
Joined : 2011-06-15
Location : Lincolnshire
Auto-Sleeper : Duetto

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Stewart John on Mon Feb 24, 2014 9:50 am

Hi

Thank you for that Doctor Dutto I not be able sleep tonight thinking about all that.    hugegrins

_________________
Stewart
avatar
Stewart John
Member
Member

Male

Posts : 283
Joined : 2012-01-15
Member Age : 69
Location : Loughborough
Auto-Sleeper : Topaz 2.0 2014

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Gram on Tue Feb 25, 2014 5:06 am

Thank you very much, Dutto, for the comprehensive description.

In a nutshell - keep the screen uncovered, add a little heat at night.

.......and hope the high humidity levels in the van are a result of our wet weather and nothing more sinister.

G
avatar
Gram
Member
Member

Male

Posts : 253
Joined : 2013-02-21
Member Age : 73
Location : Hants
Auto-Sleeper : Symbol
Vehicle Year : 2009

View user profile

Back to top Go down

Re: Windscreen Condensation

Post by Dutto on Tue Feb 25, 2014 8:21 am

Gram wrote:……...

.......and hope the high humidity levels in the van are a result of our wet weather and nothing more sinister.

G
… like mice making hot passionate love and steaming up the windscreen??  Whistle1 

Best regards,
 drinksallround 


PS

Daftest question I have ever heard asked.

Quiet lane …

… car with windows steamed up …

… against my advice, fellow policeman decides to investigate …

… sneaks up on car and pulls open back door to reveal a couple in flagrant delicto.

"Are you two together?" he asks! 

 Whistle1  Whistle1

_________________
Dutto - Living more in hope than expectation; and seldom disappointed!
avatar
Dutto
Donator
Donator

Male

Posts : 7866
Joined : 2011-06-15
Location : Lincolnshire
Auto-Sleeper : Duetto

View user profile

Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum