Wind chill and frozen pipes again

[trader4]

He didn't rattle my cage. The first response from a rattled cage was from philo. Everyone up to that point, had ignored it.

[micky]

If your pipes don't perspire or leak, if they're not wet on the outside, wind chill is not a factor. It doesn't exist for pipes that are not wet on the outside. Even though plenty of people talk like it does.

It doesn't exist for cars, either, unless they are wet on the outside. Not "were wet" but "are wet".

It exists for people, who perspire, a little bit everywhere I think. The wind blows across the wet skin, even so slightly wet that it doesn't feel wet, and the water draws heat from the skin as it evaporates. The quantity of heat needed to make water evaporate, the heat of vaporization, is the same as the heat required to raise the temperature of the same amount of water by 15 or 20 degrees, iirc. It's the same amount of heat needed by water about to boil on a stove, to go from water to water vapor, although I guess one cannot tell by looking how much heat that is.

I don't know about other animals. Dogs pant, but do they in very cold weather? Probably not, and I've never heard of a dog's tongue freezing because of wind chill. They probably keep their tongues in their mouths.

The wind doesn't matter, but the 0F does.

If it is actually zero where the pipe is, yes.

LIke under the trailer maybe, where it's not heated? What do other people with trailers do? If you live in a trailer park, you'd find more people who know abou tthis there than you willl here. Or at least they should know what they do and what happens to their pipes when they do it. Even if you don't live in one, go visit one and ask them. Isn't there usually a manager. He should know what to do.

Whichever pipe is exposed to the very cold temperature. Both of them, if that is the case.

Perhaps, but that won't cause the pipes to freeze.

[micky]

How can that be. Water expands iirc between 33 and 32^F. So it reaches its greatest volume at 32. What does 20 have to do with it?

I know that warmer things surrounding the water continue to heat the water, but that's only if the things are warmer. They are losing heat too for the same reason the water is.

[micky]

It's reasonable to doubt this, but I think it's true.

If you check the 15F column, a 5MPH wind lowers the perceived temp to 7F and 10MPH to 3F.

I feel like it is cheating to look it up but

The human body loses heat through convection, evaporation, conduction, and radiation.[1] The rate of heat loss by a surface through convection depends on the wind speed above that surface. As a surface heats the air around it, an insulating boundary layer of warm air forms against the surface. Moving air disrupts the boundary layer, allowing for new, cooler air to replace the warm air against the surface. The faster the wind speed, the more readily the surface cools.

The speed of cooling has different effects on inanimate objects and biological organisms. For inanimate objects, the effect of wind chill is to reduce any warmer objects to the ambient temperature more quickly. It 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 maintain surface temperature in an acceptable range so as to avoid adverse effects. Thus, 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 increasing the risk of adverse effects.[citation needed]

A surface that is wet, such as a person wearing wet clothes, will lose heat quickly because the wet cloth will conduct heat away from the body more rapidly, and because the evaporating moisture carries away heat.[citation needed] Conversely, humid air slows evaporation and makes a surface feel warmer, and this is incorporated into longer wind chill formulas. During warm months, this effect can be described in the heat index or humidex.

[DerbyDad03]

...snip...

Not my pug! His tongue is almost always hanging out his mouth, from as little as an inch to as much as 4".

I don't know about windchill, but I do know that his tongue will stick to a cold metal pole if he gets too close.

This isn't my dog, but I've seen this situation in real life more than once.

[clare]

Wind chill is not just about evaporation. It is "removal of heat" period. On a human body it is how quickly the body gets below it's normal temperature to the point you get frostbite. Evaporation is PART of it - but evaporation would be faster in a "dry cold" which does not feel as cold as a "damp cold"

The standard Wind Chill formula for Environment Canada is: TWC=13.12+0.6215Ta-(11.37V+0.16)+(0.3965TaV +0.16)

where TWC is the wind chill index, based on the Celsius temperature scale, Ta is the air temperature in degrees Celsius (°C), and V is the wind speed at 10 metres (standard anemometer height), in kilometres per hour (km/h).[10] The equivalent formula in US customary units is:[11] TWC=35.4+0.6215Ta-(35.75V+0.16) + (0.4275Ta(V+0.16)

where TWC is the wind chill index, based on the Fahrenheit scale, is the air temperature, measured in °F, and is the wind speed, in mph.[12] Windchill temperature is defined only for temperatures at or below 10 °C (50 °F) and wind speeds above 4.8 kilometres per hour (3.0 mph).[11]

So, in North America humidity has no "input" into the calculation.

[clare]

It is heat loss by CONDUCTION that is affected by wind "chill" as it strips off the "boundary layer" of warm air that naturally clings to the body.

How FAST is the critical point. How FAST does a bottle of water at

96F freeze???? The windier it is, the faster it will freeze at any given temperature (32F or below)

[trader4]

Reasonable to doubt what? I didn't say that wind doesn't lower the preceived and actual skin temperature. I just said that I doubt the dominant factor there is *evaporation*, because IDK about you, but my exposed skin doesn't sweat at 15F. But the blowing wind sure carries heat off of skin, just like it does from any other object that is above ambient, including water pipes.

Totally consistent with everything I've said. And note that they do say it affect *inanimate* objects, which is exactly what I have been saying and which was the main point of contention in the previous long thread about this. You had a certain poster claiming that windchill has no effect on inanimate objects, which is wrong.

Again, totally consistent.

[Stormin Mormon]

Yep, it's going to be near zero a couple days this week, which is -17c for centigrade folks.

With the wind chill so far below zero, I think it's a good couple days to leave a faucet drip over night. I'm trying to decide to drip the hot or cold. So far, been thinking hot.

Might also cardboard and staple over some windows that don't really need light coming in.

[Stormin Mormon]

Best I've heard in ages. You're first rate, in spite of what people say.

[clare]

Dripping the hot will still allow the cold to freeze - I'd keep them all dripping, or drain them all.

[Stormin Mormon]

That's wise counsell. I do remember a friend of mine who left one drip, and the other froze.

[Bob_Villa]

r pipes to burst.

From the old post:

"This has nothing to do with wind chill...but it gives you pretty much the magic number for a pipe to burst. From "The Weather Channel"!

When should homeowners be alert to the danger of freezing pipes? That depen ds, but in southern states and other areas where freezing weather is the ex ception rather than the rule (and where houses often do not provide adequat e built-in protection), the temperature alert threshold is 20°F.

This threshold is based upon research conducted by the Building Research Co uncil at the University of Illinois. Field tests of residential water syste ms subjected to winter temperatures demonstrated that, for un-insulated pip es installed in an unconditioned attic, the onset of freezing occurred when the outside temperature fell to 20°F or below.

This finding was supported by a survey of 71 plumbers practicing in souther n states, in which the consensus was that burst-pipe problems began to appe ar when temperatures fell into the teens. (Note: Please disregard any wind chill! *J*)"

[clare]

Note - that is with pipes in an ATTIC. Heat rises. We are talking pipes in and under a "redneck bungalow" - close to ground level. My guess is 20F is about 5 degrees late on a breezy day and 7 degrees late on a windy one.

A good row of hay bales around the bottom of the trailer before the snow fell would have helped considerably - likely making 25F safe. Mabee better. And a couple of 100 watt bulbs would then help keep them from feezing to quite a bit lower temp. Then again, I don't know just how BAD Stormy's trailer is. I know some I've seen down around Ellicotville and south would hardly pass as chicken coops up here. Likely cost twice as much to heat as my 3 bedroom two story.up here in Central Ontario

[gregz]

I was doing some more sealing cracks at my old house. The wind gets into them.

Greg

[micky]

Well, that makes it one to nothing in favor of panting in cold weather. I had never paid attention, so I was just guessing.

Tongues probably have a good blood supply, I'll bet. Is that what makes them red?

No kidding? How often has he done that? Were you there to free him?

I can see why a dog wouldn't anticipate this problem. Chidren don't either Really, how could they unless they red a lot?

[micky]

Okay. So it's the temperature in practice. Which is affected by all the factors.

It makes sense. I know pipes don't burst the moment the temp hits 32, or even 31.

Thanks.

[trader4]

for pipes to burst.

he magic number for a pipe to burst. From "The Weather Channel"!

pends, but in southern states and other areas where freezing weather is the exception rather than the rule (and where houses often do not provide adeq uate built-in protection), the temperature alert threshold is 20?F.

Council at the University of Illinois. Field tests of residential water sy stems subjected to winter temperatures demonstrated that, for un-insulated pipes installed in an unconditioned attic, the onset of freezing occurred w hen the outside temperature fell to 20?F or below.

hern states, in which the consensus was that burst-pipe problems began to a ppear when temperatures fell into the teens.

+1 The poster took what is clearly offered as a general guideline for outside temps and freezing pipes in an *attic* and made it appear it applies to freezing pipes in general. If you have a piece of exposed pipe filled with water outside, I agree that I would expect it could easily freeze and bust long before 20F.

[trader4]

BS. Following that theory, a car radiator is transfering just as much heat with no air moving through it as it is with a high volume of air moving through it.

Wrong. If you have a brick that is 100F and you put it outside when it's 50F, does it cool off faster with or without a fan blowing on it?

Even though plenty of people talk like it does.

Then feel free to block the airflow to your radiator. It will still transfer the same amount of heat, right?

You completely ignore the heat removed by *convection*. It doesn't have to be wet. If it is wet, then yes that increases the heat transfer.

Which has nothing to do with the situation at hand.

And people don't sweat on their exposed skin when it's 15F either.

and I've never heard of a dog's tongue freezing

Of course the wind matters. You think it takes just as much energy to heat a house when it 0 with a 45 MPH wind and without? Good grief.

Just if it's zero? Just a drip? Good grief.

Yes, great idea. I live in a house and I should go survey folks who live in a trailer. Good grief.

Isn't

And I'll bet if the pipes are really exposed to the very cold, eg 0F number you cited, that they will freeze with just a drip anyway. The lower the temp, the more exposed, the more water you need flowing.

I can see why.

[Stormin Mormon]

I've not seen hay bales any where else in the trailer park, not sure it's allowed. I'd have to ask, some time. Might be able to rig some thing with fiberglass, behind the skirting.

Some years ago, a couple friends and I blew cellulose into the ceiling, and that helped a lot. Used to have icicles down to the ground. From the lost heat.

When I go out for more than an hour or so, I turn down the heat to 60F, figure that cuts my heat bill a bit. Only runs two or three minutes to recover when I get back. Sometimes, I'll light a stove burner during the warmup period.