adithorp
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| posted on 29/1/08 at 06:40 PM |
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Demist/heater dumb idea?
Some one was looking over my car todayand asked about demisting? So I explained the alternatives (heater matrix and box, electric fan heater, electric
heated screen) and he said, "Why don't you just suck hot air from around the exhaust manifold with an axial fan and duct that to the
screen?".
So why don't I? Worked for VW Beetles (well was supposed to).
adrian
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blakep82
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| posted on 29/1/08 at 06:45 PM |
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i had though about this myself once or twice... wouldn't fancy it if the exhaust started leaking though 
and i guess you can't adjust the heat...
but yeah, can't think of a proper reason why not
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IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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tegwin
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| posted on 29/1/08 at 07:02 PM |
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The cabin heat in the R-22 helicopter is just that..
Cold air drawn in over the exhaust muffler into the cabin...
The pilot manual says that you should have the nose air vent open if you use the heater to prevent death
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Howlor
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| posted on 29/1/08 at 07:02 PM |
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I ensured my beetle heat exchangers and channels were in tip top condition. The heat got so severe I managed to melt a plastic bag where the outlet
was on the passenger side!
I am sure it woudl work and only like a beetle as you say.
Steve
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David Jenkins
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| posted on 29/1/08 at 07:03 PM |
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Well, when I get into my tin-top at 7:00am on a cold Winter's morning, the screen's misted up and the engine's cold. I'd have
to wait quite a long time to get enough hot air through to demist the screen!
Mind you... the usual solution (hot coolant through a heater matrix) takes quite a while...
Maybe you should try the VW army vehicle solution - have a petrol heater that lights up on demand, to supply hot air!
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rusty nuts
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| posted on 29/1/08 at 07:05 PM |
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Have you ever driven an air cooled VW in cold weather? You would be better off eating a Polo mint and breathing on the screen. And yes I do know what
I'm talking about I worked at a VW main dealers for years . If I build another 7 type car I will go for a heated front screen rather than a
heater.
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SeaBass
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| posted on 29/1/08 at 07:16 PM |
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quote:
Originally posted by David Jenkins
Maybe you should try the VW army vehicle solution - have a petrol heater that lights up on demand, to supply hot air!
lol - Not just the army vehicles. Quite a few normal campers had these fitted too...
Called an Eberspracher heater I believe - and very effective they are!
Cheers
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skodaman
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| posted on 29/1/08 at 07:23 PM |
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"You would be better off eating a Polo mint and breathing on the screen. "
Ah so this is the much vaunted Polo heater that is often recommended. There was me thinking it was a heater unit from a VW Polo.
Seriously though the heated screen in my Mondeo is rubbish cos it takes ages to have any effect. Better to just stick the fan on full even when
engine cold. So can't imagine the Caterham heated screen is worth the £300. Only thing it really achieves is gets u through sva without having
a heater and fan fitted.
Skodaman
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Werner Van Loock
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| posted on 29/1/08 at 07:48 PM |
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Eberspacher and Webasto do the fuel powered heaters. Also used a lot in older trucks and a lot in boats.
I was thinking about 12V hairdryer, maybe paintstripper, don't know what the internal voltage is.
Another possibility is the "pc power supply with toaster heater wire"
 
Heater
Really locost it is 
http://www.clubstylus.be
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DarrenW
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| posted on 29/1/08 at 11:06 PM |
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Old guy was telling me today that when he was younger, and in those days there were proper frosts in the morning, the trick was to remove fuel filler
cap (diesel trucks), stick rolled up newspaper in, light it and use the fire to clear the screens (outside only).
Not quite a demisting reply i know
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rick q
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| posted on 29/1/08 at 11:25 PM |
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Sucking air from adjacent the exhaust is how mine is - though it only feeds demister vents for rego purposes (like your SVA I s'pose).
Not really effective in my case, but it could have been made better by ducting right up to the manifold itself. (No longer needed now it's
registered!)
You won't do it with an axial fan - they don't develop enough pressure - use a centrifugal fan instead.
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whitestu
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| posted on 30/1/08 at 08:26 AM |
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Citroen GS heater worked like this, and worked well. With the VW the hot air has to come all the way from the back.
Stu
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dhutch
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| posted on 30/1/08 at 10:21 AM |
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quote:
Originally posted by Werner Van Loock
Eberspacher and Webasto do the fuel powered heaters. Also used a lot in older trucks and a lot in boats.
Yeah, there not allways very reliable however. (well, on narrowboats anyway)
- And there also expesive, and diesal based!
Exhast sounds like a vauge plan however. Could always try it i guess!
Daniel
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Schrodinger
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| posted on 30/1/08 at 01:46 PM |
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I used two 12v hair dryers for my vents and it got me through SVA, I'm not even sure that the have to be hot air though.
Car Builder Solutions do a fan in some trunking for about 25 IIRC that would provide the airflow for you.
Just checked they do and Axial fan http://www.nfauto.co.uk/axial_fan.htm but not low cost!
It was the Merlin catalogue http://www.merlinmotorsport.co.uk/p7545/3%22-DIAMETER-IN-LINE-BLOWER-FAN/product_info.html that had the fan I was thinking
about.
[Edited on 30/1/08 by Schrodinger]
Keith
Aviemore
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blakep82
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| posted on 30/1/08 at 06:56 PM |
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i was thinking 2 of these...
http://www.nfauto.co.uk/demist.htm
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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adithorp
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| posted on 30/1/08 at 11:31 PM |
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I've got a pair of electric fan heaters (£10 each from a caravan shop) which I was intending to use. Then heard of Jimgibett's group buy
of heated screens so changed plans and will use one of them instead as its not a lot more than a normal screen. This idea was just something that I
was asked and didn't know if it had been done before.
VW Sharrans (and Galaxys) have diesel fired heater boosters under the rear floor.
adrian
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