[Closed] Defrosting car windscreens with hot water

I've defrosted this way for 20 plus years & not had a problem but I do only use 20C water.

Use cold water numpty, it still defrosts it 😀

yup, cold water here too for last 15 years with no probs

turn your engine on, turn the heater on and use a window scraper with a bit of effort behind it.
you don't need water or de-icer or anything. usually just makes it harder, IME.

Use a bank/credit card to take the ice off - better than any scraper.

Heated windscreen on my Mondeo. What is this scraping of which you speak?

Use cold water numpty, it still defrosts it

Gah.I guess it was hotter than I thought it was, and quite cold out.

Like I say - never had it happen before. Glad it was my gash alfa, not the wifes nice car.

clear your shed out & put the car inside 😆

HTH

Insurance will cover it, won't it?

>Insurance will cover it, won't it?

Yes, even idiocy in this case.

i have always used warm water on my cars , never had any issues at all.
even my car with lightweight thiner glass (i kid you not)hasn't cracked........ yet

why not just start the car up, put the blower on full blast and go back inside for a cuppa tea ?

While someone steals your car? 😉

Yup,also a warm water user for over 25 years(when we used to have proppa winters)& no ****ed screens here either....

Wife's car got a heated front screen & it aint as quick as the water method 8)

use cold water,

hot water actually freezes faster than cold water,
i dont understand the physics behind it,

but if you dont believe me just google it

warm water & wipers on fast is the way to go....

Used a CD case impromptu yesterday to de-ice. Worked a treat and no icy fingers of using credit card technique.

"hot water actually freezes faster than cold water"

its on the internet so it must be true!

think about it logicaly for a few seconds.............................

high tempreature water in a bucket (90deg C), low tempreature water (20deg C) in an idetical bucket (no treadmills or aeropanes involved)

presume ground is perfectly coducting and has a tempreature of -10deg C, and the air tempeature is -10deg C

The rate of evaporation (and so cooling by the enthalpy of vapourisation) is (for the sake of argument assumed to be, we wont go into 5 film theory, an convection currents) proportional to tempreature. Ditto the rate of heat loss by conduction.

So initialy the hot bucket loses heat (and thus lowers in tempreature) at a greater rate than the low tempreature bucket.

But as it cools this rate lowers.

so when the high tempreature bucket is at 20deg C, its rate of heat loss will be the same as the low tempreature bucket was originaly, however, the low temp bucket has now cooled to 5 deg, etc etc etc

Yes i have heard of the Mpemba pheomenon, but that only aplies in certain coditions, in reality you'd have to devise your experiment to take advantage of it.

oh gawd here we go again,
you put the hot water into a airplane shaped ice cube tray,
then straight into a freezer which is on a conveyor belt

thisisnotaspoon that's what i thought the cold water has a head start in freezing
no!!!!

http://www.google.co.uk/search?rlz=1C1GGLS_en-GBGB309GB310&aq=f&sourceid=chrome&ie=UTF-8&q=hot+water+freezes+faster+than+cold+water

check out my last paragraph, its a phenomenon that exists, i dont doubt that, but thats like saying everyone drives bugatti's, based on the evience that 1 person does.

start engine, back in side, cup o tea, back out window clear .mainly with frost but if its heavy snow it helps as well because you just brush the snow of with big brush

the 2 buckets is the precise experiment where hot water will freeze before the cold, given that they are in the same environment.

dont poo-poo the idea, i remember seeing it on a children's program, it might have been "how 2"
and they dont lie 🙂

stand on the roof and piss all over the windscreen, cleared in seconds...

Used water on car screens for years clears it instantly and never had one crack. No doubt it can happen with hot enough water and a really cold day.

wouldnt just be 2 buckets, the buckets would need to be the right shape/size and filled to the correct level as well,

and it presumes no forced convection, i.e. your not stirring it, so the situation where its runnig down your windscreen in a very thin film, is probably about as likely to exibit the Mpemba phenomenon as i am to win the lottery (nearly impossibe seeing as i dont play)

Colande sounds to me as if he knows what he's talking about.

You on the other hand Spoony, what you're saying just sounds like nonsense to me.

.

Plus, you don't appear to have watched the children's programme which he's talking about.

grizzlygus - Member
Colande sounds to me as if he knows what he's talking about.

You on the other hand Spoony, what you're saying just sounds like nonsense to me.

Plus, you don't appear to have watched the children's programme which he's talking about.

😀 haha grizzlygus, seeing that he hasn't seen the children's program in question i pronounce myself the winner,

edit; http://www.discoverychannel.co.uk/web/mythbusters/experiment/ice/

no ive not seen the TV program............................

but i did research it for part of my degree :p

Same here, I use lukewarm water and it clears all the windows with one jug full. Put wipers on and it's dry so it won't freeze again.

Very hot water just seems a bit extreme!

i did research it for part of my degree

So how come you don't know about the experiment then ?

Did I and other taxpayers pay for your degree level education ffs ?

Pour it on the front of the roof and let it run down the screen, works for me. But there again I onlt have to do it once in a blue moon as I ride to work all week.

Water that has been boiled (but then allowed to cool to ambient temperature) will freeze quicker than cold (ambient temperature) water.
It's about the air content within the water.

Start the car ,lock the car then go in for tea.
I tried the water method but it ended up in the locks and then they would freeze up, Don't suppose that matters as much with the remote locking now come to think of it

I'm a W/Screen tech. and can't believe u tworts use hot water to clear ure screens !!!
You all deserve to have your W/S excess's TREBBLED !!!!

scraping the windscreen takes approx 30 seconds and, unless you use a brick, doesn't break it.

Another happy user of ford's heated windscreen here 😀

Also loving my Ford Quick Clear windscreen here. I juts have to start it up, scrape the 4 side windows and the front is done!

Yep also loving the QuickClear.

Though I can go one better: I just get in and say "Defrosting on!" in my best Captain Picard voice.
Front and back windows heat up, blowers come on for the side windows, wing mirrors heat up and my washer water is also heated.
Meantime I sitback and quietly chortle at the guy turning blue who has just broken his credit card on his window.

Toys are great!

loving the heated windscreen on my mondy too, but why dont Ford licence it to other manufacturers?

I just get in and say "Defrosting on!" in my best Captain Picard voice.

Must be a bit of bugger if you get laryngitis in winter then. As not only will you have a sore throat, but you can't drive your car anywhere - poor you 😯

Scraping seems to work for me. You've got to clear all the windows anyway not just the windscreen. Plus, even if you clear the outside of the windows of ice, the inside fogs up in really cold weather until there's some warm air blasting out, air con or not. My wife starts the car, puts the screen heaters on at full and then locks the car with the other key and goes back inside for a cup of tea.

Just clear a small slot in the screen, jump in the car and go.

grizlygus, thats a bit harsh, and i did mention the effect, its called the Mpemba effect/phenomenon after they guy who re-discovered it, but the effects been known for hundreds of years.

Several hypothesis' for why it happens;
convection (the one i looked at)
gas content (proven not to be significant if at all)
supercooling (unlikely, this only hapens in perfectly polished containers with absolutely no contaminents)
solutes (would have an effect, but not at the levels foud i tap water, maybe if you used batter?)

in basic terms i was trying to show that the inertia of a convection current could sustain a warmer layer of liqid on the surface of a container, thus increacing th evaporation rate.

The answer was yes, it can be made to cool faster.

Other things that affect it are the way the ice forms, the cold beaker with no/little covection would form ice on the surface, thus blocking further heat loss, and slowing down its freezing. The warm beaker maintains warm water at the surface (increacing evaporation) and freezes from the bottom.

Gas content has been rueled out, you can repeat the experiment with two beakers of boiled water one at 90deg and one at 10deg, the same thig hapens.

However, i highly doubt the thin film of water flowing down your windscreen is moving slowly enough, and lasts long enough for the effect to occour.

I always imagined that it would be due to loss of a larger proportion of the hot water by evaporation, leaving less to freeze

oh, and my 15 year-old kit car has a heated windscreen (and sometimes my wife dresses up a lieutenant Uhuru and spanks me with a hairbrush)

grizlygus, thats a bit harsh

Well maybe it is. But you come on here claiming some sort of expert, and yet it's obvious that you haven't even watched the Discovery Channel programme.

grizzlygus - Member

But you come on here claiming some sort of expert, and yet it's obvious that you haven't even watched the Discovery Channel programme.

The program was "How 2", please read my post properly grizzlygus

I did read your post properly. I'm refering to the Discovering Channel experiment which you linked. This one :

To demonstrate it yourself you will need:

* two identical containers of the same size and shape
* access to cold water
* A kettle
* A freezer large enough to hold both of your containers

[img] [/img]
[img] [/img]
[img] [/img]
[img] [/img]

I'm going to try to carry out the experiment myself sometime tommorrow - perhaps you should give it a go too Spoony ?

if it's not been on Brainiac then I don't believe it.

[i]and sometimes my wife dresses up a lieutenant Uhuru and spanks me with a hairbrush[/i]

I don't believe that either, pictures please as proof. (of your wife dressed up), I have no desire to see you being spanked......unless you're quite tasty).

i run the tap until hot water comes through, fill the kettle and lightly splash it onto all the windows.then i go around and aggresively pour the lot onto it. if i need more roasting hot water i go get more.ive got a few chips in the screen and never had a screen crack doing this.

the temps are,obviously, around zero right down to -13c.through November the whole month was pretty much around -3c min and i used hot water each time.ive tried warm and compared to how snow and ice melts with the hot water.. i think ill be sticking to what ive been doing for years as its the best for quick clearing.
I`m starting to wonder if folk on here do things certain ways because thats what is scientifically proven by brainiacs stuck inside some lab.. nowhere near the real world. As for starting the car up and leaving it running as you have a cup of tea, thats not getting the engine etc working up to temp correctly at all. you could damage parts prematurely doing that.common sense.not only that, someone could steal the thing.

I wont keep quiet if i crack my screen. i WILL let you know.

Yep , i can also say defrosting on, but i only ever use the voice commands on my galaxy for dialling on the phone from the memory( but use the radio panel for dialling numbers!) the rest is just over kill!!

It is kind of cool to set the diesel pre heat but i always forget to set what time i want it to come on!

warm water and windscreen works fine, starting car and leaving it unlocked is bad as the insurance does not pay up, what is worse was someone fro work who loaded their car, started it up and went back inside promptly losing a laptop and docs all marked up not for the casual reader

grizlygus, i presume your trolling comparing your imense ammount of knowlage of the subject gleaned from a kids TV program to the general confusio the effect caused aristotle and bacon?

your avoiding the point, i never said it wouldnt work in a bucket, (i said it wouldn't work in two perfectly mixed buckets).

your windscreen with hot water flowing across it is going to be a laminar flow (d is very small, probably a couple of mm) so the promary mechanism for heat transfer will be diffusion (also very small), so all we can say is that what is going on on the upper surface will be having no effect on whats hapening on the screen.

Now think about the time it takes for the water to run down your screen. very short, so its fair to say there will be no time for a convection current to form.

Also, your pouring the water, if you stood in your freezer replicatig the experiment pouring boilig water into the bucket its no going to freeze.

The effect exists, i never said it didnt, i said its irrelavent to the situation in question.

'As for starting the car up and leaving it running as you have a cup of tea, thats not getting the engine etc working up to temp correctly at all. you could damage parts prematurely' How would that damage parts and how is that not warming the engine? Nonsense!

[i]How would that damage parts and how is that not warming the engine? Nonsense! [/i]

Apparently it doesn't work anywhere near as well as just getting in the car and driving it; leaving a car engine running to "warm up" is pretty pointless. I heard some AA man saying it so it must be true.

Oh and heated front windscreen here too. 🙂 I've used lukewarm water in the past if I can't be bothered waiting.

Remember to leave an icy puddle in the road for a cyclist to skite on later.

They love that!

Engine gets to temperature much quicker if being gently driven than ticking over, which is obviously better for it.

Also parts can coke up if engine is left ticking over for too long.

Though I can go one better: I just get in and say "Defrosting on"

Odd my 04 reg Mondeo doesn't need to be told to switch it on. Switch the ignition on, it beeps for "chuffing cold out" (ie 4C or below, as I live in the South) and then it switches on both front and rear heated screens for me.

I use the wife's hairdryer and a long extension lead to defrost my windscreen 🙂

Lukewarm tapwater, wipers on. Bobs your uncle. NO need for hot water if you use your wipers FFS.

^what he said

i use luke warm water all the time, and we have a crack...

then again its just easier to use a scraper!!!

Yep , i can also say defrosting on, but i only ever use the voice commands on my galaxy for dialling on the phone from the memory( but use the radio panel for dialling numbers!) the rest is just over kill!!

Nah they are ace. Tuning the radio, messing with the sat nav, changing the temperature, demisting, defrosting, making calls. Granted you can do all these things remarkably easily by simply pressing a few buttons, but it's nice not to have to.

More importantly it makes me feel like Michael Knight.. a lone crusader in a dangerous world. 😀

[img] [/img]

Odd my 04 reg Mondeo doesn't need to be told to switch it on. Switch the ignition on, it beeps for "chuffing cold out" (ie 4C or below, as I live in the South) and then it switches on both front and rear heated screens for me.

Yeah weird that. On mine (Ford Focus) it knows that it is cold out, cos it lights up a little red snowflake on the dashboard and it has an external temperature reading, but it still needs you to press a switch or voice command to actually do anything about it.

[i]Odd my 04 reg Mondeo doesn't need to be told to switch it on. Switch the ignition on, it beeps for "chuffing cold out" (ie 4C or below, as I live in the South) and then it switches on both front and rear heated screens for me.[/i]

It then went on to blow its injectors, DMF, other engine electronics etc and the nice Mr Ford always welcomed me to the dealership with a big fat smile? 🙄 😆

That picture of the Hoffmeister is really messing with my head.

Cbike - glad you mentioned the moronic action of using water - ever considered why there is so much ice on the floor round where you park the car??? Just scrape the bloody things.

Living in the frozen uplands, I get frosty car windscreens probably 50-60 days per year. It takes all of two minutes to clear all the frost with a scraper. I'm struggling to ascertain why I'd possibly bother going in an out with a kettle...

It takes all of two minutes to clear all the frost with a scraper. I'm struggling to ascertain why I'd possibly bother going in an out with a kettle...

agreed.

I hate it when people complain about boffins in a lab not living in the real world. Boffins do live in the real world, most of them are quite intelligent. People who complain about boffinry are just not grasping the concept of science at all - so don't brag about your ignorance.

Sounds like nonce-sense if you ask me. I find a scraper works fine (or if you can't find one, just place your palms flat on the screen and use body heat to defrost it).

Being working class ,I lick the screen on my car to clear the ice.
When I say car ,I mean cart .
And when I say screen I dont actually have one.
When I say cart ,actually its a pair of boots.
Well ,sandals.
A sandal.
Well ,a buckle.
When I say working class I mean serf.

My jocky wheels froze up over the weekend.

You guys. It must be ace.

I use a scraper most mornings. When it hits about -10 the scraper breaks before the ice does. At this point I use luke-warm water, this warms the screen thoroughly so my breath doesnt freeze on the inside which it does when I've just scraped it, plus it thaws the wipers that are usually frozen in a manner that means they cant physically wipe the screen. It also means I can drive straight off and warm the car up on a run, instead of idling it to warm which isnt good and is a waste of fuel.

AndyP - Member
Sounds like nonce-sense if you ask me

Dumb idea leaving your engine running to warm the car up. Engine wear is at its most extreme when cold. At tickover you have very little oil pressure. Maximum wear + minimum oil pressure = engine bu**ered 10 times quicker than normal

Engine wear is the worst when the engine is cold for the first few seconds I once read - something to do with SO2 or NOx combining with the water vapour produced by burning those first few cylinder fulls of fuel then condensing on still cold valves/cylinder walls or whatever. Which is why you mustn't start the engine then gun it hard as soon as it kicks, like some folks do.

If I were designing an engine, I'd make sure that there was enough oil pressure to circulate oil at tickover, for exactly the reason that CM quotes. Most journeys start with a lot of tickover when the engine's still cold...

My Prius incidentally runs the engine at not much more than tickover when you start it and uses mostly electric power, for about 30 seconds or so. Apparently it's to let the engine warm up and circulate oil without stressing it.

[i]My Prius[/i]

😥 Mummy, that man is evil 😥

Surely which (hot or cold water) freezes first is irrelevant in this situation?

We aren't trying to freeze water, we're trying to melt ice.
Presumably a sufficient quantity of water is used to prevent it freezing before the ice is thawed. Given this, surely it should be fairly self evident that the warmer water will thaw the ice faster?

I think the lesson we can all take from this is:

Brant drives a niche car.

Clever, these modern cars, aren't they?

Saw a bloke with one the other day.

'Come on, you ****ing useless **** thing, WORK!'

It din't though; I suspect he'd possibly not calibrated the voice-recognition feature correctly...

My Prius

Mummy, that man is evil

Bring it on 👿

There's a lot of complicated discussion going on for what should be a simple act - buy a scraper for 50p and scrape the windows while they're dry. So much neater than messing with kettles. Anyone else have to scrape inside the windows of their car?