Wind chill and water pipes

[Gordon Shumway]

Huh?

Umm... technically, the temperature where ever the pipes are IS the ambient temperature for that portion of the pipe.

[nestork]

The pipe will cool down to 0 degrees F., and no colder. The wind chill only means it'll cool down faster than if there was no wind.

The correct way to think about it is that if the ambient temperature is

0 deg. F, then the pipe and the water in it will not get colder than 0 degrees F.

The greater the wind chill, however, the faster a pipe with warm water in it will cool down to 0 deg. F.

Wind increases the RATE of heat loss, not the ultimate temperature a body cools down to. If the pipe were to get colder than 0 degrees F, then the stronger the wind, the faster it would be warmed up by the air to 0 degrees F.

So, if your pipe is gonna burst, it'll burst a few minutes sooner with a wind than without, but the strength of the wind only determines how quickly that pipe cools down, not what temperature it cools down to. It cools down to the ambient temperature, which is the temperature without considering any effect of wind chill.

[SteveB]

Has everything to do with the individual situation. Any wrapping? Any heat that can transfer from living space? Is pipe in insulated wall? Is there dead air space around pipe, or is it vulnerable to the wind?

Lots and lots and lots and lots of variables, according to many things, right down to what pipe is made of.

Steve

[Stormin Mormon]

Yep, better leave a faucet dripping, tonight. Thank you, that's great common sense.

[Stormin Mormon]

SM: Yes, yes, yes.

SM: Might want to go back and research what wind chill is. It has to do with the heat loss as a function of time.

SM: So, the pipe is going to freeze sooner. That matters, as it will warm up tomorrow, and I don't want the pipes to freeze tonight.

[Stormin Mormon]

It's going to warm up tomorrow. Since the wind chill freezes pipes sooner, it's definitely a concern, and I do need to consider the wind chill. Thank you.

[DerbyDad03]

In the past, it's been cold (colder) where you live in. Have you always left a faucet dripping? Have ever had a frozen pipe?

[Stormin Mormon]

When it gets down below 10 or so, I do try and remember to leave a faucet drip. So far, not had any frozen pipes.

I'm not eager to reverse the experiment, close the faucet and see if they freeze.

[Ed Pawlowski]

nestork gave a good explanation, but instead of wind chill. we should call it wind effect.

Does the wind hit the pipes? If yes, it can carry heat away faster, if no, it won't matter how strong the wind is.

When the weatherman gives wind chill numbers, he is talking about how human skin exposed to the wind feels. I was just out in my garage at -7 wearing a heavy jacket, hat and shorts. No wind, it was not a big deal.

[Stormin Mormon]

SM: From the curb valve (of sorts) to the bottom of the traileer has foam wrap and heat tape. Once it goes into the floor, no wrap.

Any

SM: The tube from the curb valve to the floor has pretty much no heat that can transfer.

Is pipe in insulated wall? SM: Much of it (about 30 feet) is not.

Is

SM: The trailer has skirting, but I'm sure there is air that goes through. Bitter cold air, too.

SM: 3/8 soft copper. Which splits when it freezes.

[trader4]

ote:

Actually you contradicted yourself:

" "Wind chill" has absolutely no effect on inanimate objects. The wind on an inanimate object will cool an inanimate object to the ambient temperature quicker than no wind."

Wind chill is a measure of the how wind causes people to feel colder. It also has a similar effect on cooling inanimate objects that are warmer than ambient. Therefore it can have an effect on objects that are warmer than ambient.

Will a pail of water at 75F freeze faster if you put it outside where it's exposed when it's 20F with a windchill of 17F or a winchill of 5F?

What the temperature in the

Only if you define ambient temperature as the temperature at the pipe. If by ambient you mean the outside temperature, then the temperature in the wall is likely to be lower with a wind blowing on it than without.

Wind is a component of wind chill. Would you not be more concerned about pipes freezing on a day when the wind chill is 0F than when it was 17F, even if the outside temp both days was 20F?

[trader4]

Of course it doesn't have time in it's calculation, which is irrelevant. A bucket of 75F water placed outside when it's 20F with a wind chill of 0F will freeze faster than it will when the wind chill is 17F. Therefore windchill does matter with inanimate objects, in some cases.

That's like saying the pipes will freeze if they will freeze. Sure, if you want to define ambient to be the temperature at the pipes. But who measures that? The point is if one hears that it's going to be 20F tonight, is there valid reason to be more concerned about pipes in an outside wall, a drafty crawlspace, etc freezing if the reported windchill is 0F versus 17F? The answer to that is yes.

Which shows that by ambient, you're using the outside air temp, which is what most people would be looking at when trying to decide it their pipes are going to freeze, because they have no way of knowing what the ambient temp at the actual pipe inside the wall is. Now, you're trying to change ambient into the temp at the pipes hidden in the walls, which no one would even know. It's simple. Whatever the reported outside temp is, the lower the windchill, the greater the possibility that pipes in an exterior wall, drafty crawlspace, etc will freeze.

Here's another question. If inanimate objects are not affected by windchill, then on a night when the outside temp is 20F, the same house is going to use the same amount of energy to keep it at 70F when the windchill is 0F as it does if the windchill is 17F?

[trader4]

That isn't true. Take a somewhat drafty crawlspace. Put a thermometer a various places inside it. Measure the low temps recorded when:

A - It's 20F outside and no wind

B - It's 20F outside and there is a 35mph wind.

You think the low temps are going to be the same?

That's a real potential pipe freezing example and the lower the wind chill, the more likely the pipes will freeze.

Yes, if the body is fully exposed. But many, probably most pipe freezing situations are one where the pipe is not outside, but partially protected, eg the crawlspace example. If it's fullly exposed, then it;s likely drained, winterized, etc.

If the pipe were to get colder than 0 degrees F,

Per the crawlspace example, it can also effect what low temperature it sees. Here;s another example. Suppose you have a cabin with water pipes inside. The cabin is at 40F. Overnight it's going down to

20F. Do you not agree that it's more likely the pipes will freeze with a 35mph wind blowing, hence a windchill of 3F, than it would be with still air and a windchill of 20F?

[Gordon Shumway]

No, I didn't contradict myself but you just did. "Wind chill" has no effect on an inanimate object. Wind chill is just how cold ambient temperature feels to exposed flesh.

Now can you agree that "how cold it feels to exposed flesh" has no effect on inanimate objects?

The wind (not wind chill) will have an effect on heat transfer.

[trader4]

Well, no shit Sherlock. Apparently windchill does have an effect on an inanimate object.... And let's look at the context, before you try to hijack it into something else. The question that was asked was if wind chill was a consideration in pipes posssibly freezing.

Your answer, which you apparently cling to, is that wind chill has no effect on inanimate objects.

Wrong, as demonstated by physics and my various examples.

BS. Wind chill is an index that indicates how wind and in some cases evaporation, factors in to cooling things. Those "things" could be you or an inaminate object that is above the outside temp.

Are you really saying that a house with no heat, there is no reason to be more concerned on a night when the wind chill is 0F, as opposed to 20F, even if the outside temp is the same? Yes or no?

How it "feels" matters not a wit. The fact that wind chill is directly dependent on wind speed and that it can effect how pipes may freeze in a crawl space, an unheated cabin, etc is fact.

Wrong, because the only component other than temp, of "wind chill" is windspeed, at least in the US.

Non answer noted.....

[Ed Pawlowski]

Let's change the parameters. Outside temperature is 35 degrees, but because of the wind, the weatherman says the wind chill factor is 29 degrees. Will the pipe freeze? No.

In your example you use an example of 17 and 0. The only difference that may have a minor effect is if the wind is actually moving the air away from the pipes. Many factors come into play on how the wind moves around the pipes inside the crawlspace. It does not determine if the pipes will freeze, on;y how fast. Rate of heat transfer is the only difference, the temperature never goes below ambient.

The big difference is how well sealed the house is. Radiational cooling difference will be minimal, but convection can be considerable.

[Gordon Shumway]

"Wind chill" has no effect on inanimate objects. Period, if I may quote our fearless leader.

Your various examples are merely demonstrating the effect of wind, not wind chill. Until you can understand the difference there is no further point in this conversation.

If I may paraphrase another of our presidents, It's the wind, stupid.

[krw]

No, but it will cool faster. Wind chill is still relevant to inanimate objects, even above freezing.

...or the wall (and the pipes indirectly)

Right but that's not the issue at hand.

Well, wind chill has no bearing on radiation cooling.

[Gordon Shumway]

You would have been 100% correct if you had left off the word "chill."

[mike]

YEP!!! Wind CHILL is an empirical determination of what happens to humans in cold wind. It's the same principle, but the NUMBER is relatively useless for freezing pipes in unspecified configurations. It is likely that lower wind chill number will be harder on pipes, for the same wind direction relative to the structure. How much depends.