De-icing test. - David W
Had to use SWMBO's BX Estate today. This car stands out and, due to a high moisture level inside from muddy wellingtons/wet mats the ice is as much inside as out.

Thought I'd try the mains fan heater trick as mentioned in previous threads. Absolutely brilliant!

Popped the extension lead out from the shed and put a small fan heater on the passenger floor. Set the 1KW output, thermostat to medium and left it for ten minutes.

On returning not only was the car warm but all the ice had gone from the outside of the windows as well as the ice/condensation from the inside.

Just like driving it away on a summers day.

David
Re: De-icing test. - Mark (Brazil)
I went out this morning, started the car, put the air-conditioning on max and went back in for a cigarette and coffee.

Since Guy explained to me that idling the car was a problem mostly because of its operating temperature, and I swear that these days mine is that hot before I started it, I guessed it would be ok.

I didn't know whether to put the aircon on recirc or outside air, so I put it in the middle.

Mark.

p.s. this is nothing to do with your thread at all - I am merely gloating because it ain't cold here !!
Re: De-icing test. - David W
Mark,

Guess you're not sitting in the house with a scarf on then.

Wish I could get past the network administrator password on the central heating boost button.

Also wish it wasn't too cold to take off the back door and fit a new (well better anyway) one. That old one with a bin liner for glass can't last much longer.

Bet John S budgets more than £12 for a replacement door.

David
Re: De-icing test. - Mark (Brazil)
you don't get that door done soon, you gonna get a slap !!
Re: De-icing test. - Alwyn
MArk,

Did you get my e-mail with TRL 323?
Re: De-icing test. - Mark (Brazil)
Yes, and I replied to you this morning.

Thanks, I'll let you know my thoughts when I've torn it apart.

I have to say that the intention seems good, and the recording method, on the face of it, is acceptable although flawed. However, some conclusions seem a little wayward.

I'll let you know.

M.
Re: De-icing test. - David W
Quite.
Re: De-icing test. - John S
If I was really sensitive, I'd think this was some sort of poke at my taste in cars and southern spending habits......

At 55 merely enjoying the fruits of my labours a little, before I'm too old!

Don't talk to me about cold. When I was a lad, I used to wake up with frost on the inside of the windows.

regards

John
Re: De-icing test. - Anthony Farrar
I used to wake up with frost on the inside of my eyelids
Re: De-icing test. - ladas are slow
i still DO wake up with frost on the inside of the windows, and sometimes you can see your breath indoors.
Re: De-icing test. - ladas are slow
dw, the back door on this house is the original, and its held together with bits of cardboard.
Re: De-icing test. - Brill
Would it be ok to have a timer switch in the garage connected to a fan heater, set to blow hot air under the engine for (say) fifteen minutes before setting off? Or would heating the outside of the engine be of no use? Alternatively I could follow DW and put the heater 'inside' the car.

Mark (B), I assume setting your aircom to recirc will cool the trapped air better than letting warm air in which will require further cooling.

Stu.
Re: De-icing test. - Brill
Sorry, I see you covered the 'recirc' question in your earlier thread.
Re: De-icing test. - rg bhaji
Fan heater has worked fine for me for years. Probably cheaper than de-icing fluid even though using 1kw heater.

Just watch that the flex does not too get frayed where it goes between the door and the sill. Could result in an excellent anti-theft device...

rg bar-g
Re: De-icing test. - Dave
David W wrote:
>
> Thought I'd try the mains fan heater trick as mentioned in
> previous threads. Absolutely brilliant!

This morning as I left my house there were no less than 4 car left running in the bitter cold.

A bit of Dunkirk spirit between us as we scraped away/waited.

If it gets any colder I'll be needing some Hiroshima spirit! ;-)
Re: De-icing test. - Alwyn
Why not use warm water to de-ice a recently discussed? Works fine and no waiting.
Don't use water! - ian (cape town)
Alwyn, all depends (Before you ask why am I commenting, as we never get ice here... I've lived in some pretty cold places)
Take a glass, place in freezer, leave for a few hours, take out, and fill with warm water.
Wear gloves.
The point is, the screen may expand and crack.
This is especially poignant if the wind has been blowing - the screen may be 5-6 degrees BELOW the air temperature, due to accumulated windchill.
Another problem is the run-off, which can get into gaps and refreeze when you start moving. Wiper arms, door keyholes, under window seals - all very susceptible, and easily damaged.
Hope this helps.
(Phew! what a scorcher here, by the way...)
Windchill fallacy - John S
Ian

Oh dear, the old wind chill fallacy again.

Windchill was devised as an approximate means of assessing the additional heat removal effect of wind on the human body. The human body tries to maintain a steady temperature. Air isn't a particularly good conductor of heat, but if the wind blows then the air immediately adjacent to the body is constantly removed, and the body loses heat faster. Wind chill factor tries to calculate an equivalent static air temperature which equates to the actual air temperature and the heat removal effect of the windspeed.

However it cannot and does not have any relevance to inanimate objects like cars and windsreens. If the air temperature is,say, 0C no matter how fast the wind blows your windscreen will not get below 0C! Yes, the car will cool down faster, but to drop below the temperature of the surrounding air would contravene the laws of physics! Heat can only flow from a hot body to a cold body, and once the car and the air are in equilibrium that's it.

This one usually occurs with the instructions for 'add-on' external temperature gauges which are suggested installed behing the bumper 'to avoid windchill'. No surprise that Vauxhall and BMW (to name but two who who understand the science) ignore this advice!

regards

JS
Re: Windchill fallacy - ian (cape town)
John,
My head is both bloodied and bowed!
Re: Windchill fallacy - John S
Don't worry about it - there are plenty out there who need it explained - go spread the word!

Regards

John
Re: Windchill fallacy - ian (cape town)
Aaah! Dug out the details, and I was wrong ... but right!
It transpires that, under ceratin conditions, the temperature drops to silly levels overnight. Over a period of time (4-5 hours) , the INSIDE of the vehicle chills down, and as the outside air heats up, the inside remains cooler! SO! When the outside expands, so the inside (up to 5 degrees colder) won't expand at the same rate, hence the water cracking the glass.
Again, my apologies for my earlier ignorance, but the point is - DON'T pour water on the windscreen!
Re: Windchill fallacy - Alwyn
Wonder why glass tumblers don't craaack when we put our hot LemSip in them.
Re: Windchill fallacy - steve paterson
On a frosty night, a cooling system filled with plain water might not freeze. But driving the car before the thermostat has opened can result in the water in the radiator freezing, due to the wind chill. I realize that the radiator is being cooled by the airflow to the ambient temperature, but in practice if not theory, windchill is going to cause the subsequent problems.
Re: Windchill fallacy - John S
Steve

The effect here is that when the car is standing overnight it takes much longer for the engine and coolant to cool. It may not get down to freezing point. Once you drive it, the air flow increases the rate of cooling, but it is not possible to get the water below the temperature of the air.

regards
john
Re: Windchill fallacy - John S
Alwyn

It depends how thick they are. Thick glasses will be more prone to cracking under those circumstances. The heat from the hot liquid will take a finite time to travel through the whole thickness. In a thick glass, this will result in stresses being induced as the hot inner surface attempts to expand, but is restrained by the cooler outer surface. These stresses can be sufficient to cause the glass to shatter. Small imperfections will act as stress raisers, and cracking will start at these points. I don't recommend you have your Lemsip from a cut glass tumbler for that reason!

Pyrex doesn't suffer from this problem as it is borosilcate glass with a very low coeficient of expansion.

You'll remember from Chemistry lessons at school that laboratory glassware is very thin - and thus heats through quickly and doesn't crack.

regards

John
Re: Don't use water! - Dave
ian (cape town) wrote:
>
> This is especially poignant if the wind has been blowing -
> the screen may be 5-6 degrees BELOW the air temperature, due
> to accumulated windchill.

Bzzt. Wrong.

Wind chill refers to a *rate* of cooling. No matter how much wind there is it can't cool something to a temp colder than the actual temp.
Re: Don't use water! - ian (cape town)
ok, ok. don't rub it in.
Re: De-icing test. - Dave
Alwyn wrote:
>
> Why not use warm water to de-ice a recently discussed? Works
> fine and no waiting.

I do sometimes - I find the scraping quite soporific and by the time I've gone back to the house it's doesn't take that much longer.
Re: De-icing test. - Brian
If they were on the road rather than on your drives, you were committing an offence!
Re: De-icing test. - Dave
Brian wrote:
>
> If they were on the road rather than on your drives, you were
> committing an offence!

Really!!! What is the offence?

If it's ok, I won't shop my neighbours to the Rozzers...
Offensive ... - ian (cape town)
Leaving a vehicle with engine running unattended.
link to story... - ian (cape town)
news.telegraph.co.uk/news/main.jhtml?xml=/news/200...l
A MAN who returned to his doorstep to kiss his wife and baby goodbye after leaving his engine running while it warmed up was fined £30 by a passing policeman.

Matt Puttock, 28, a medical supplies sales manager, claimed that the police action was petty and said he was prepared to go to court to fight the fine.

"I couldn't believe it," he said yesterday. "Thousands of people across the country must do this in the mornings." Mr Puttock, of Ruspidge, Forest of Dean, Glos, said he had started his car on a freezing morning when his wife, Lucy, appeared at the door with their 15-month-old daughter, Daisy.

He went back to the house to say goodbye and when he returned he was told by the policeman that it was an offence to leave a vehicle unattended with the engine running. The policeman issued a £30 spot fine.
Re: link to story... - Anthony Farrar
What's a spot fine?
Re: link to story... - FfwlCymraeg
Something you get in Hackney?

Acne, gerrit?

Aw please yourselves.
Re: Offensive ... - Dave
ian (cape town) wrote:
>
> Leaving a vehicle with engine running unattended.

Thanks Ian!

I wonder how many people were burgled on the day this act of valuable community policing was performed.

Ours weren't unattended though!
Re: De-icing test. - KB
I would say no, Brill, to the idea of heater under engine. Really can't see it doing anything apart from warming up any stray cat's which may start to gather there. Stick it somewhere safe inside the car on 1kw for 10 minutes - LUXURY! Mind you, if your car is IN the garage, you won't have any ice / mist to clear?? It'll still be cosy and warm though. Do it!
Re: Don't use water! - Brill
KB,

... "Mind you, if your car is IN the garage..."

Ah, but my Yorkshire mother says I'm "Nesh" (soft).

Stu.
Re: Windchill fallacy - alvin booth
John S.
I can't disagree with what you say. however.......
With regard to external temperature displays there is something I can never fathom. I have one on each car and they both repond in the same manner.
One in the Vectra is factory fitted and where the sensor is I have no idea.
The other on the maestro is under the front bumper well away from the radiator. However after being on the move for a while in any weather they both rise after a while by 2 or 3 degrees. Yes I know you could say well its got warmer but that isn't the answer and I'm not sure what is.
One other factor in heat transfer is that it transfers at a faster rate when there is a greater differential. (For instance a household radiator). And another factor of heat transfer in this case is strangely enough the colour of the paint used on the radiator. Tables are shown in FW Overtons textbook of the diffferent heat transfer rates appertaining to different colours and silver as I recall gave the lowest for some reason.
Alvin
Re: Windchill fallacy - markymarkn
With regards to the different colours of paint effecting heat transfer. This is true - I remember an experiment from school using a device called 'Lesley's Cube' in which 1 side was polished silver, one silver and rough, one polished black, on black and rough.

The polished silver side was most resisitant to heat absorption because it would reflect the majority of incoming radiation, whilst the rough black side absorbed the most. Similar results for heat loss.

Also, the colour black absorbs the majority of the electromagnetic spectrum in order to show the colour as 'black' (as opposed to white which reflects most of the spectrum).

From what I recall the radiator in my astra is matt black, and so is pretty much every other standard radiator I have seen.

Any comments chaps?

Mark.
Re: Windchill fallacy - John S
Mark

Spot on! Surface colour and finish affects the rate of heat radiation and absorption. That's how aluminium 'space blankets work'. They minimise heat loss by radiation, being smooth (minimum surface area) and polished (minimum heat radiation).

Ever seen or used one of the remote temperature sensors? They work by measuring infra red radiation. The big problem is calibrating them. Once while trying one out we came across two pipes which a surface probe showed to be operating at identical tempertures. The problem was that one had new, shiny aluminium cladding over the lagging, whilst the other was dull. The machine indicated they were at greatly different temperatures. Rather detracts from the value of the machine! Never had a really lucid explanation from the makers either regarding calibration.

Most car radiators were painted black, I guess for maximising heat transfer. However, many makers don't seem to bother these days with the aluminium units. I can only assume that radiation is a minor component when you have a large airflow and most heat transfer by conduction.

Damn, I've used parentheses, must rewrite!

regards

John
Re: Windchill fallacy - Stuart B
John S wrote:
>
> Ever seen or used one of the remote temperature sensors?
> They work by measuring infra red radiation. The big problem
> is calibrating them. Once while trying one out we came
> across two pipes which a surface probe showed to be operating
> at identical tempertures. The problem was that one had new,
> shiny aluminium cladding over the lagging, whilst the other
> was dull. The machine indicated they were at greatly
> different temperatures. Rather detracts from the value of
> the machine! Never had a really lucid explanation from the
> makers either regarding calibration.
>

Quite! It's all down to the emissivity factor. You should have had a control on the IR pyrometer to alter it.

As for calibration; to do it properly is an absolute pig. Unfortunately the most practical method for bodgers like me is to use a calibrated contact pyro to determine the true temperature of the surface to be measured. Then point the IR pyrometer at the surface and fiddle with the emissivity knob till you get the right answer. In that way you could have established that the setting for reading one pipe was x and the second pipe y. This hopefully would have given some repeatability in future measurements.

No doubt the manufacturers waffled on about setting up a source of black box radiation, yes? no?
Re: Windchill fallacy - john fitton
For many years I have used a storage heater [old toaster with irreplacable duff element, leaving 500w useful heat, containing broken roof tile to stop rattles] plugged via boot ['90 Audi 100E] to socket on nearby wall. Timeclock switches it on about an hour before departure.

. It is strapped firmly to the front of the driver's seat and warms [and continues to warm one or other hand and backs of legs for first two miles] , steering wheel, de-ices windscreen and side windows. So far I have not emerged from the house to find a charred shell, but I gather the market value is only thruppence anyway.
Re: Windchill fallacy - Julian Lindley
John,

I chuckled at your earliar comments.

I also remember my bedroom windows frozen on the inside in the morning. Like you I'm 55 too so decided to treat myself - hence the recent aquisition of an MB. Up until then I had been quite content doing large annual milages with my old Cavalier. My Uni' based daughter continues motoring with the old Vauxhall.

Some science to support contributor argument or (otherwise) is much appreciated - thanks

Regards,

Julian
 

Value my car