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TDI 101 Got a simple/basic TDI question? Are you a newbie (new to the forums). Feel free to post your question here.

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Old February 6th, 2018, 14:28   #16
NoSmoke
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Quote:
Originally Posted by fouillard13 View Post
no it doesnt. itll cool it off faster when its warm, but overall temperature is overall temperature, like the engine would be on a cold morning. the engine temp is what your digital readout says, its what the mercury thermometer says, its NOT the wind chill temp.

why do you think mercury thermometers dont read wind chill temps?

plus, how does wind hit the engine block? or the pistons?

edit: tdawson beat me to it, and much more elegantly
Mercury thermometers don't read wind chill temps because they are at ambient temperature.

As I said, through the grill perhaps. Or turbulence under the engine compartment. The lower than otherwise temperature of the pistons is caused in turn by conduction through the block.

You say at first "it'll cool off faster when it is warm". Well, that's what wind chill does - the blowing wind removes heat from a warm object and it cools faster or, does not get as warm (from a block heater for example) as it would if the wind was not blowing.

Any evaporating moisture on the surface will add to the cooling effect but in itself is not necessary for a cooling effect to take place - only motion of cooler air past the object is required and the faster the wind, the greater the cooling.

Try this for further explanation:

https://en.wikipedia.org/wiki/Wind_chill

The money shot is:

"A surface loses heat through conduction, convection, and radiation.[1] The rate of convection depends on both the difference in temperature between the surface and the fluid surrounding it and the velocity of that fluid with respect to the surface. As convection from a warm surface heats the air around it, an insulating boundary layer of warm air forms against the surface. Moving air disrupts this boundary layer, or epiclimate, allowing for cooler air to replace the warm air against the surface. The faster the wind speed, the more readily the surface cools.

The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. Dry air cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity. For most biological organisms, the physiological response is to generate more heat in order to maintain a surface temperature in an acceptable range. The attempt to maintain a given surface temperature in an environment of faster heat loss results in both the perception of lower temperatures and an actual greater heat loss. In other words, the air 'feels' colder than it is because of the chilling effect of the wind on the skin. In extreme conditions this will increase the risk of adverse effects such as frostbite."

Note that moisture is not mentioned in the explanation as moisture is not a requirement.
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Last edited by NoSmoke; February 6th, 2018 at 14:33.
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Old February 6th, 2018, 15:10   #17
Vince Waldon
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This article talks about "perception" actually... which is my personal understanding of what "wind chill" is... us sweating mammals perceiving it's colder than it actually is.

If you leave your car overnight and the weatherman tells you "it's -30, -40 with the wind chill!!" nowhere on the car will you measure anything other than -30. The car does not perceive it's colder than -30, and the starter/oil/glowplugs are working against -30, not -40.

The human standing there swearing at his car that won't start does however perceive it to be -40 out. Evaporation on exposed skin makes it seem colder than it actually is.

And yup, if you get started, drive around for a while, and then park the car will cool off faster with a wind blowing thru the grill than on a calm day (rate of heat loss, as mentioned in this same article). But never will the car get colder than ambient.

Apples and oranges in this thread, I think.
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Note: The above is to the best of my knowledge- but at the end of the day simply interweb opinion, worth EXACTLY what you paid for it, and if used done so at your own risk.
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Old February 6th, 2018, 15:17   #18
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NoSmoke;

You missed this at the beginning of your referenced Wikipedia link;

Wind-chill or windchill, (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air.

It has no effect on mechanical objects. They are at ambient temperature.
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Old February 6th, 2018, 15:43   #19
fouillard13
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Quote:
Originally Posted by NoSmoke View Post
Try this for further explanation:

https://en.wikipedia.org/wiki/Wind_chill

The money shot is:

"

The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. Dry air cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity. For most biological organisms, the physiological response is to generate more heat in order to maintain a surface temperature in an acceptable range. The attempt to maintain a given surface temperature in an environment of faster heat loss results in both the perception of lower temperatures and an actual greater heat loss. In other words, the air 'feels' colder than it is because of the chilling effect of the wind on the skin. In extreme conditions this will increase the risk of adverse effects such as frostbite."

Note that moisture is not mentioned in the explanation as moisture is not a requirement.
my mercury thermometer is right outside, hung on the house wall by a window.. exposed to the wind just like everything else.


the second paragraph you posted basically confirms what I said. it "feels" like -40, when really its only -30 out. it gets to ambient temp quicker, but not a degree lower. moisture has nothing to do with windchill or cars. its just the technical scientific reasoning as to why humans skin is affected by cold wind so much.

same thing in your living room... that bare steel leg on your table? I bet you think its colder than the couch cushions? its not, its the exact same temp! everything in your room is. its just that its a better conductor of heat and pulls heat from your hand quicker is all. it just "feels" colder because heat is leaving your body quick enough. thats all cold is, is a lack of heat.

you think -40 is cold? theres actually still a lot of heat potential there... you can pull heat out of a piece of steel until it hits -460F. interesting stuff.

boy has this thread ever got derailed!
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Old February 6th, 2018, 15:44   #20
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Quote:
Originally Posted by Beaker80 View Post
NoSmoke;

You missed this at the beginning of your referenced Wikipedia link;

Wind-chill or windchill, (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air.

It has no effect on mechanical objects. They are at ambient temperature.
Oh for heavens sake. That is wind chill ("factor") as applied to humans. Did you read the stuff I posted?

We are talking about the effect of wind chill on a VW with a heater. The "mechanical object" at issue here is NOT at ambient temperature as it is being heated and is therefore warmer than ambient (but not as warm as it would otherwise be because of the suggested possible wind (chill)).

This debate is starting to remind me of the HP vs torque sillyness. Perhaps apples & oranges as Vince says...
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Old February 6th, 2018, 17:39   #21
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Originally Posted by NoSmoke View Post
Oh for heavens sake. That is wind chill ("factor") as applied to humans. Did you read the stuff I posted?
We are talking about the effect of wind chill on a VW with a heater. The "mechanical object" at issue here is NOT at ambient temperature as it is being heated and is therefore warmer than ambient (but not as warm as it would otherwise be because of the suggested possible wind (chill)).
This debate is starting to remind me of the HP vs torque sillyness. Perhaps apples & oranges as Vince says...
Yes I did and again windchill has nothing to do with mechanical devices. Only living beings. Did you read??? I agree that a very cold ambient day (-30) will cause a greater heat loss from the Zerostart heater or any heating device(like a running engine). That's thermodynamics. Noting to do with windchill.
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Old February 6th, 2018, 18:47   #22
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Originally Posted by Beaker80 View Post
Yes I did and again windchill has nothing to do with mechanical devices. Only living beings. Did you read??? I agree that a very cold ambient day (-30) will cause a greater heat loss from the Zerostart heater or any heating device(like a running engine). That's thermodynamics. Noting to do with windchill.

What is the difference (apart from possible surface moisture) between a warm "living being" and a warm "mechanical device" when both are exposed to colder moving air? We are talking about heat transfer in either case i.e. heat transfer from a warm object to the colder air.

What would happen to the temperature of a human or, a human dummy (i.e. a "mechanical device") similarly clothed and with similar surface colour and texture and with an internal heat source equal to that of a human? Would it be any different? If so, why?

I might also ask, what exactly is your definition of "windchill". If by "windchill", you are referring to a phenomenon that by definition applies only to living things, then we are simply having a pointless debate about semantics. That is the only logical explanation I can come up with for your assertion that "windchill" has nothing to do with mechanical devices".
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Old February 6th, 2018, 19:02   #23
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chill
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Old February 6th, 2018, 19:10   #24
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Originally Posted by maxmoo View Post
chill
At this juncture that sounds like good advice.

Since we only seem to be wasting each others' time (and we have hijacked the OP's thread), I think I'll bow out now.
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Old February 8th, 2018, 12:45   #25
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Originally Posted by SnapRattleKnock View Post
I just installed a 750W 8000 Series Zerostart heater and I'm not impressed with the results. I followed one of the other forum posts for install. Hoses are not warm after running heater for 4 hours. Anyone else installed the 750W heater? The forum post I saw had the 1500w heater installed. Guy at the autoparts store was convinced that the 750W heater would be plenty for the little 1.9 ALH.
OK lets get back on track.

Did you remove the check ball from the inlet of the heater as per this;

http://forums.tdiclub.com/showpost.p...6&postcount=90

Is the top hose coming off the heater sloped upward so there are no dips in it?
Is the inlet hose to the heater lower than the OHE? Supposed to be.
At -30 there is a lot of heat loss. Can you insulate your grill and around the engine to retain the heat? Think of it like your house with no insulation. Your furnace will constantly run and not heat your house.
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Old February 9th, 2018, 09:27   #26
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Originally Posted by Mongler98 View Post
I forget what one i am using but if i remember right its the 750, coolant gets no where near warm (above 90F) in -30F outside all night with it plugged in all night it keeps (warm enough) the hood always has the snow melted on it and when i turn the key, its like starting it on a summers day. Thats the point with these heaters. they are cheep to install, and cheep to run. If you wanted a hot car to get into your going to spend $$$. Its normal, what is the coolant temp? do you have a digital temp readout you can measure it with?
Coolant temp gauge hasn't moved after running the heater for 4 hours. I do have a temp gauge at work ill try and see what it reads before I start it next time. Strange thing is the outlet hose from the heater is nice and warm after an hour.
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Old February 9th, 2018, 09:31   #27
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Quote:
Originally Posted by NoSmoke View Post
What is the difference (apart from possible surface moisture) between a warm "living being" and a warm "mechanical device" when both are exposed to colder moving air? We are talking about heat transfer in either case i.e. heat transfer from a warm object to the colder air.

What would happen to the temperature of a human or, a human dummy (i.e. a "mechanical device") similarly clothed and with similar surface colour and texture and with an internal heat source equal to that of a human? Would it be any different? If so, why?

I might also ask, what exactly is your definition of "windchill". If by "windchill", you are referring to a phenomenon that by definition applies only to living things, then we are simply having a pointless debate about semantics. That is the only logical explanation I can come up with for your assertion that "windchill" has nothing to do with mechanical devices".
Haha all this talk about windchill is all for not, im parked in a garage
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Old February 9th, 2018, 09:34   #28
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Originally Posted by Beaker80 View Post
OK lets get back on track.

Did you remove the check ball from the inlet of the heater as per this;

http://forums.tdiclub.com/showpost.p...6&postcount=90

Is the top hose coming off the heater sloped upward so there are no dips in it?
Is the inlet hose to the heater lower than the OHE? Supposed to be.
At -30 there is a lot of heat loss. Can you insulate your grill and around the engine to retain the heat? Think of it like your house with no insulation. Your furnace will constantly run and not heat your house.
Check valve is removed and hoses and heater seem to be installed exactly as the that post you mentioned above. Now that I look more closely though my outlet hose may be a little too long. Theres a slight dip in the hose before it goes up to the block.
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Old February 9th, 2018, 10:46   #29
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I cut about 1", from the end of the hose that enters the engine head, just to give it a little more up slope to the hose exiting the Zerostart.
Any more cutting I would be to close to where the hose turns 90 degrees towards the front of car.
This port maybe different on factory installed 5 spd, but I still have the automatic still there. The auto goes straight down.
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