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Discussion Starter · #1 ·
Is it because

1) Water expands when it turns to ice. When water in a pipe turns to ice it expands and burst the pipe.

2) when water turns to ice it compresses water downstream. This pressure in the compressed water eventually bursts the pipe, not the expanding ice.

Thanks for any help.
 

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Both 1 and 2 are the same thing. When water freezes it expands. Expanding frozen water bursts pipe or expanding frozen water compresses unfrozen water to burst pipe. Both are the result of freezing water expanding.

If you look at frozen water in a glass you will see a mount on the surface. That is the frozen water expanding. It has room to come up. If the glass was a jar with a lid it could burst if the jar was full enough and the lid tight enough.
 

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I'm not even going to read the link as increased water pressure is NOT the cause of a pipe bursting when the water inside freezes.

A. Every burst pipe I have repaired has burst right where it froze.
B. The expansion resulting from the water in one area of the pipe freezing is minute in relation to the volume of water in the system.
C. Ultimately, the pressure relief on the hot water side is still part of the system and it would release long before a pipe would burst.

Pugsy has it right, #1

Bud
 

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Bud, you may want to read that article, I know you are convinced that the expansion of the freezing water causes the pipe to burst, but the article makes a persuasive case that the pressurized water actually bursts the pipe in most cases. Article includes photos. Consider that in a pipe, as the water freezes, the ice can expand into the part of the pipe that is still liquid. On the inlet side from the street, the expanding ice can push the water out. On the outlet side in the house, the water may not have anywhere to move, for example a pipe which leads to a water faucet.

In the case where the water is trapped, the pressure will increase rapidly, since the bulk modulus of water is very high (about 320,000 psi), so a small percentage increase in volume leads to a large increase in pressure. Ice also has a high bulk modulus, so if the ice cannot expand, for example water completely fills a sealed container, then the container is frozen, the ice will crack the container.So if you freeze a full container in the freezer, you will likely crack the container.
 

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I did read the article and do understand what he is saying, but it doesn't match what I've seen in the real world. Pipes where the water has been left running can still freeze and burst where the ice is. Frozen pipes that are 20 feet away from any closed faucets still freeze and again burst where the ice forms.

I'm not a plumber so repairing burst pipes has only be the occasional task, but I will keep his explanation in mind if the future presents me with any more burst pipes. Doubtful given my age.

I agree it is a possibility.

Bud

PS I knew you were going to make me read the article :).
 
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Discussion Starter · #11 ·
Because it has room to expand at the top.
There is no room for expansion in a closed water pipe.
It can expand upstream into the water supply system. That is less than 100psi.

I asked this question because I read both causes on genuine plumber's websites and something seemed wrong. I think the solution is #2 but I may be wrong.
 

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In a water filled closed space, including a section of pipe between two plugs of ice, the pressure everywhere within that space is the same. As additional water freezes within the closed space in question, the pressure rises more.

For the pipe where disjoint portions of the contents froze, at first the plugs of ice will crack and/or push lengthwise depending on the pressure of the water on each side of the plug but eventually the plug is too large to break up or move. Then the pipe breaks at its weakest point.

If an open glass container of water is allowed to freeze, we cannot rule out breakage of the glass if the layer of ice across the top had gotten quite thick.

Simply insulating a length of pipe passing through an unheated area might not protect it from freezing. Usually the pipe relies on itself conducting heat from the interior of the building and hopefully the far end, for example the hose bibb, is the coldest and freezes first with freezing gradually progressing inward so there is never a pocket of water with plugs of ice on both sides. Plastic pipe does not conduct heat well and would be more likely to burst in this situation.
 

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Discussion Starter · #13 ·
... Pipes where the water has been left running can still freeze and burst where the ice is. Frozen pipes that are 20 feet away from any closed faucets still freeze and again burst where the ice forms.

This may explain your experience why pipes burst where ice forms.

http://dsplumbing.ca/plumbing-repairs/freezing-pipes-information/

Ice supposedly forms from the walls of the pipe towards the center so it may leave localized pockets of liquid along the pipe that are compressed.

I am not an expert at all.
 

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This may explain your experience why pipes burst where ice forms.

http://dsplumbing.ca/plumbing-repairs/freezing-pipes-information/

Ice supposedly forms from the walls of the pipe towards the center so it may leave localized pockets of liquid along the pipe that are compressed.

I am not an expert at all.
If ice formed on the outside walls first, the rupture in my experiment below would be somewhere in the center.

I believe both theories have merit and it's probably a mixed bag of which actually causes the rupture depending on the location of freezing.
 

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All the frozen pipe burst I’ve dealt with have showed up during the thawing cycle. As the ice thaws the water now can reach the break and there’s your leak.

If #2 was true, then pipes would be bursting and leaking during the freeze event vs when things are thawing. I won’t say it can’t happen but I’ve never seen it.
 

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Good discussion and I want to add one of the more important solutions to freezing pipes. Where wrapping them in insulation helps it will often not be enough. Where possible, insulation should be located between the pipe and the cold area and leave the pipe exposed to the source of heat, the warmth of the house.

Bud
 

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Good discussion and I want to add one of the more important solutions to freezing pipes. Where wrapping them in insulation helps it will often not be enough. Where possible, insulation should be located between the pipe and the cold area and leave the pipe exposed to the source of heat, the warmth of the house.

Bud
Good point. My inspector called this one out.
The first pic is what the "pros" did.
Second pic is my repair.
 

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Good point. My inspector called this one out.
The first pic is what the "pros" did.
Second pic is my repair.


Pugs, btw, doing a fantastic job with the house!

Bringing the supply lines up thru the floor and away from a outside wall would be another option. It's not always practical, but I try to stay out of out side walls altogether.
 

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Pugs, btw, doing a fantastic job with the house!

Bringing the supply lines up thru the floor and away from a outside wall would be another option. It's not always practical, but I try to stay out of out side walls altogether.
Thanks.

In my case above , you can see a false wall that the pipes and duct are in with a full 6" Roxul behind.

I agree about keeping supply pipes out of the outside walls. Kitchen sink is on an outside wall with supply pipes thru the floor.
 
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