Wind chill (1 Viewer)

[Touchwood]

Reading February's Practical Motorhome, I came across the following from "Diamond Dave" in the technical advice section.

"Take water tanks, for example. They're often underslung and if you're driving at 60mph, there's going to be a 60mph gale blowing along the underside of your 'van. This will create a significant wind chill factor and if the ambient temperature is low - say, around 5 deg. C - then the tanks and pipework will be subjected to a sub-zero blast that can cause water to freeze.

The solution is to insulate the tanks and pipework:...."

I'm don't wish to impugn Diamond Dave's technical expertise in other areas, but this is nonsense, and a commonly held misconception. Wind chill factor only affects bodies with their own heat source which keeps them above the air temperature (like warm blooded mammals such as you or I)

It is true that the air velocity will cause a greater rate of heat loss, but only until the temperature of the water tank has dropped to that of the surrounding air. Once the temperatures are equal, there is no temperature gradient and heat will cease to flow.

There may well be other perfectly valid reasons for insulating your underslung tanks and pipework, but wind chill isn't one of them.

 

[scotjimland]

Reading February's Practical Motorhome, I came across the following from "Diamond Dave" in the technical advice section.

"Take water tanks, for example. They're often underslung and if you're driving at 60mph, there's going to be a 60mph gale blowing along the underside of your 'van. This will create a significant wind chill factor and if the ambient temperature is low - say, around 5 deg. C - then the tanks and pipework will be subjected to a sub-zero blast that can cause water to freeze.

The solution is to insulate the tanks and pipework:...."

I'm don't wish to impugn Diamond Dave's technical expertise in other areas, but this is nonsense, and a commonly held misconception. Wind chill factor only affects bodies with their own heat source which keeps them above the air temperature (like warm blooded mammals such as you or I)

It is true that the air velocity will cause a greater rate of heat loss, but only until the temperature of the water tank has dropped to that of the surrounding air. Once the temperatures are equal, there is no temperature gradient and heat will cease to flow.

There may well be other perfectly valid reasons for insulating your underslung tanks and pipework, but wind chill isn't one of them.

As you say, just a load of bollox from an 'expert'

 

[Reallyretired]

Obviously actually knowing anything about a subject should not be a prerequisite to writing an advice column.
I would be very dubious about any of his advice however following this, but as I don't subscribe to this mag I probably won't have the opportunity.

^{_{Subscribers  do not see these advertisements}}

 

[slobadoberbob]

sums it up Jim

As you say, just a load of bollox from an 'expert'

Just about sums it up Jim


Bob

 

[Stephen & Jeannie]

Oh ye of little faith !!!

I presume that you posters don't realise that "Diamond Dave" is none other than our own much revered Dave Newell of Telford who has on numerous occasions helped out many of us when in need !:thumb:
When I get back to the UK in June, my first stop will be to his workshop for a service and a habitation check !! And not at rip off prices like some pseudo MH establishments !oh:
AND he gives Funsters a discount !:youbetcha:
This bugger Dave knows what he is talking about in my humble opinion !:Cool::Cool::Cool:

 

[icantremember]

As you say, just a load of bollox from an 'expert'

.....and of course the definition of an expert is-

"ex" = a hasbeen and
s"purt" = a drip under pressure ​

^{_{Subscribers  do not see these advertisements}}

 

[Stephen & Jeannie]

You are all very quick with your knocking posts aren't you !:Angry:
Let's hope you don't need any help in the future !

 

[scotjimland]

I presume that you posters don't realise that "Diamond Dave" is none other than our own much revered Dave Newell of Telford who has on numerous occasions helped out many of us when in need !:thumb:
When I get back to the UK in June, my first stop will be to his workshop for a service and a habitation check !! And not at rip off prices like some pseudo MH establishments !oh:
AND he gives Funsters a discount !:youbetcha:
This bugger Dave knows what he is talking about in my humble opinion !:Cool::Cool::Cool:

Had no idea Steve .. but it's still wrong..

I'm sure Dave is a good vehicle and motorhome mechanic, and from the Funsters reviews gives a top notch job.. at a decent price..

Thermodynamics should be left the scientists

 

[Forestboy]

You are all very quick with your knocking posts aren't you !:Angry:
Let's hope you don't need any help in the future !

Hear Hear

:thumb::thumb:

^{_{Subscribers  do not see these advertisements}}

 

[Touchwood]

You are all very quick with your knocking posts aren't you !:Angry:
Let's hope you don't need any help in the future !

I was careful to say in the OP that I wasn't doubting Dave's credentials in other areas - anyone can be wrong (I've even been known to be wrong meself on occasion)

I was merely pointing out that in this case he is undoubtedly in error - I also stated that it is a commonly held misconception - in other words an easy mistake to make. I don't make a habit of correcting other people's errors, but I felt on this occasion his advice could lead to unnecessary work and expense.

If others choose to interpret this instance as evidence of the general fallibility of "experts" that's hardly my fault.

 

[madbluemad]

Is this really Dave Newell or are you avin a laff.
Jim

 

[madbluemad]

If it is Dave Newell, I demand a recount on the basis of it was a "sting" guvnor.
Jim

^{_{Subscribers  do not see these advertisements}}

 

[Stephen & Jeannie]

I was careful to say in the OP that I wasn't doubting Dave's credentials in other areas - anyone can be wrong (I've even been known to be wrong meself on occasion)

I was merely pointing out that in this case he is undoubtedly in error - I also stated that it is a commonly held misconception - in other words an easy mistake to make. I don't make a habit of correcting other people's errors, but I felt on this occasion his advice could lead to unnecessary work and expense.

If others choose to interpret this instance as evidence of the general fallibility of "experts" that's hardly my fault.

Your post was NOT one of the knocking posts !

 

[JeanLuc]

When we first got into motorhoming in late 2006 and were looking around for information before buying, Diamond Dave Newell's articles were a source of help and good advice. In fact, I clipped and kept several of them for some time.
Having spoken to Dave on a few occasions, and had work done by him in Telford, I can only support the view that he is a very experienced and moreover, very helpful chap. I have never failed to get good advice and would recommend him to anyone looking for a first class motorhome engineer.
I agree that the OP was not posting knocking copy, but was seeking to enlighten and I, for one, have learnt a bit about thermodynamics today - but I still think Dave's a Diamond!

 

[Gromett]

Nice post I had never even considered wind chill as a factor in water freezing lol...

I did however have to do some research on water freezing this winter and found something out that I thought was interesting.

Water freezes at 0 and melts at 0. How does it decide what to do

At 0 degrees water will begin to freeze. The whole body of water will stay at 0 degrees until it is all frozen then it will start falling again to the ambient.

the same goes in reverse. at 0.1C water will start melting. Even if the exterior temperature gets to 10C the water will stay at 0C until it is all melted.

Finally (remembered from physics lessons) If warm water rises to the surface and cold water sinks. How come ice forms on the top.
Water has a unique property in that at 4C it becomes less dense and floats to the top. The warmest part of a pond in winter will be at the bottom which is why the fish all congregate there :thumb:. So if you fall in head to the bottom, you may not be able to breath but you will be warmer

^{_{Subscribers  do not see these advertisements}}

 

[Touchwood]

Nice post I had never even considered wind chill as a factor in water freezing lol...

I did however have to do some research on water freezing this winter and found something out that I thought was interesting.

Water freezes at 0 and melts at 0. How does it decide what to do

At 0 degrees water will begin to freeze. The whole body of water will stay at 0 degrees until it is all frozen then it will start falling again to the ambient.

the same goes in reverse. at 0.1C water will start melting. Even if the exterior temperature gets to 10C the water will stay at 0C until it is all melted.

Finally (remembered from physics lessons) If warm water rises to the surface and cold water sinks. How come ice forms on the top.
Water has a unique property in that at 4C it becomes less dense and floats to the top. The warmest part of a pond in winter will be at the bottom which is why the fish all congregate there :thumb:. So if you fall in head to the bottom, you may not be able to breath but you will be warmer

It's all to do with latent and sensible heat. Sensible heat is the heat energy which changes the temperature of a substance - in the case of water it's approximately 4.2 kJ per kg for every degree change in temperature. so a 1 kg mass of water cooling from 1 deg. C to 0 deg. C loses 4.2 kJ of heat energy.

Latent heat is the heat needed to change the state of the water - from water to ice for example - and this is a much bigger amount. To change 1 kg of water to 1 kg of ice needs a loss of 334 kJ - about 80 times as much energy as it takes to cool the same amount through 1 deg. C change in temperature.

The density change at 4 deg. C is a remarkable phenomenon - it if weren't for this fortuitous fact there would be no possibility of life surviving in water in colder climes, as any body of water would freeze from the bottom up and become a solid block of ice. As it is the ice forms on the top and effectively insulates the body of water thus slowing down the freezing of the lower levels. It's arguable that life on earth couldn't have developed if it weren't for this.

Fascinating stuff, science

 

[Gromett]

Fascinating stuff, science

Absolutely

Check this page out. Water is an amazing substance.
Broken Link Removed

 

[dave newell]

My thanks to Touchwood for politely pointing this out, I was wrong, simple as that. To all the other posters knocking all I can say is I actually don't really care very much what you think of me but I would suggest people think a little before posting nasty comments. My thanks to those who posted in a positive light for me.

I will correct my error in another issue.

Cheers all. D.

^{_{Subscribers  do not see these advertisements}}

 

[scotjimland]

Your post was NOT one of the knocking posts !

well, must be mine..

I make no apology, if I read something I know is wrong, I'll say so .. no matter who writes it.

If that's knocking.. so be it.

 

[dave newell]

well, must be mine..

I make no apology, if I read something I know is wrong, I'll say so .. no matter who writes it.

If that's knocking.. so be it.

So nice of you to say so Jim.

"As you say, just a load of bollox from an 'expert'"

I do find this a bit offensive to be honest, what say you?

D.

 

[Techno]

I can wholey confirm that wind chill affects solar panel fitters on motorhome roofs, those that don't have a workshop cushy like lol.
Saturday this warm blooded nutcase was pretty chilled in a near 20 mile per hour wind but the sikaflex don't mind and my customer was out there freezing with passionate interest and a happy bunny. Bring on the sun!
Link Removed
Link Removed

^{_{Subscribers  do not see these advertisements}}

 

[pappajohn]

even if wind chill was a factor you have moving water in your tank.

stagnant ponds may freeze but a flowing river will need a hell of a lot colder temperature

 

[scotjimland]

So nice of you to say so Jim.

"As you say, just a load of bollox from an 'expert'"

I do find this a bit offensive to be honest, what say you?

D.

I gave you credit in an earlier post ... but you choose to ignore..

why have you not commented on the OP, rather than having a pop at me. ?

I've said all I have to say .. my comment was on the article posted.. end of.

 

[dave newell]

I gave you credit in an earlier post ... but you choose to ignore..

why have you not commented on the OP, rather than having a pop at me. ?

I've said all I have to say .. my comment was on the article posted.. end of.

Your first post on this thread was offensive.

Am I supposed to thank everyone who says something nice?

I did comment on the OP, I publicly accepted I'd made a mistake and thanked Touchwood for his polite posting.

Your comment was rude and offensive, end of!

Other were also rude and offensive but you got in first!

D.

^{_{Subscribers  do not see these advertisements}}

 

[MHVirgins]

I have read a lot of Dave's articles in Practical Motorhome in the past, as a newcomer to motorhoming, and have always found them to be very informative and read them with interest.

However, regardless of the "science" around the freezing of water etc it takes a lot for someone to come back and admit that he had got it wrong. :thumb:

Many wouldn't even bother to do so.

Bill

 

[Stephen & Jeannie]

I gave you credit in an earlier post ... but you choose to ignore..

why have you not commented on the OP, rather than having a pop at me. ?

I've said all I have to say .. my comment was on the article posted.. end of.

When you are in a hole ! stop digging ! Your words were offensive, admit it !oh:

 

[scotjimland]

Your first post on this thread was offensive.

Am I supposed to thank everyone who says something nice?

I did comment on the OP, I publicly accepted I'd made a mistake and thanked Touchwood for his polite posting.

Your comment was rude and offensive, end of!

Other were also rude and offensive but you got in first!

D.

I missed your comment on the OP .. my apology for that..

When it was pointed out it was you who wrote the article I was surprised, as I know your reputation ... so I responded by saying

"I'm sure Dave is a good vehicle and motorhome mechanic, and from the Funsters reviews gives a top notch job.. at a decent price.. "

can't say more than that.. we all get it wrong occasionally .. just as you did ..

^{_{Subscribers  do not see these advertisements}}

 

[scotjimland]

When you are in a hole ! stop digging ! Your words were offensive, admit it !oh:

I'm not in any hole.. but if you feel that way, report it and I will take the ban .. no problem,

better still.. save you the bother, I'll just go quietly and let you all get on with the mutual appreciation society.

 

[Carol]

Jim we have a lot of knowledgeable and helpful people on Fun which is what makes it great and you are one of the best.

Think that Dave said he got it wrong takes a bit of doing, and he is really helpful and constructive with any quires when we have asked for help at any of the shows he does.

Dare I say it but a bit less testosterone,:Blush: men

 

[scotjimland]

I have never knowingly offended any member of this forum.. it is not my style.. I think the thousands of posts I have made stand testimony to this. I go out of my way to be helpful wherever possible.. not to offend or slag people off.

I did not know who 'Diamond Dave' was before this thread.. I've never read Practical Motorhome or any other publication he writes in.. so my comment was made about an article in a magazine by someone I had never heard of. If I had known it was Dave I would have chosen my words more carefully.. as it was, I wrote the first words I thought of.

I make no apology for saying the article was bollox.. but, I do apologise to Dave for calling him a 'so called expert' .. for clearly he is an expert in his field.. and well respected by many.. but again I stress, this was not known to me before this thread so my comment was not about or directed at Dave but to an unknown (to me) writer.

I hope that settles it, I hate when people fall out over mistakes.. as I said.. we all make them, ..... it's a chill wind that blows nobody any good!

^{_{Subscribers  do not see these advertisements}}