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What does it take to freeze copper pipes, a few hours or several days below 32?

What does it take to freeze copper pipes, a few hours or several days below 32?


  #1  
Old 11-29-18, 07:27 PM
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What does it take to freeze copper pipes, a few hours or several days below 32?

I'm hearing/reading two schools of thought, one is that one cold night can freeze pipes. The other is that it takes several days where the temperature never gets above freezing.

Above ground I use the pex tubing and that seems to be good.

The main line comes into the (uninsulated) basement where copper pipes are.

I have heat tape wrapped to those pipes but nothing to insulate the heatwrap from the cold so I assume the heat just blows away. The pipes are, for the most part, in the center along the basement ceiling.

In the past the basement's been ok, it's been the upper floors that have burst (hence the upgrade to pex).

This is in a rental by the way where its not always occupied and I'm rarely there.

So far I've just gone to the upper floor and run both the hot and cold water for a few minutes anytime the temperature's been cold but if only a few hours can freeze the pipes then maybe I have to insulate them, not a task I look forward to due to the messiness of how the pipes are structured.
 
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Old 11-29-18, 08:45 PM
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It depends on just how cold - will freeze a lot faster at 10F than 30F.

Either way, listen carefully when you warm everything up as you can usually hear the leak from a freeze burst.
 
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Old 11-30-18, 03:45 AM
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Pex is not freeze proof, it can only be frozen with water in it a few times and will eventually burst.
Pex needs to be treated like copper tubing.
Also, insulating piping will only slightly extend the amount of time it takes to burst.
To ensure you will not have water damage from freezing you need to permanently have heat added to the piping, either with heat tape or raising the temperature in the space surrounding the piping.


The heat from a heat tape is transferred to the pipe by it being in direct contact.
It needs to be tightly wrapped and secured at both ends so it doesn't loosen.
Some types of non-self regulating tapes are not to be overwrapped with insulation as it can overheat and burn out.
Non-self regulating heat tape should also not be wrapped over itself because it can overheat where it contantacts itself.
 
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Old 11-30-18, 03:51 AM
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A lot depends on how the pipes are exposed to the cold, just being inside the house/walls offers some insulation. I wouldn't expect protected pipes to freeze in just a few hours. The pipes in my crawlspace are either insulated or protected by heat tape and I don't have any freeze worries unless the temps get down to about 0

IMO if the house is going to set vacant for any length of time in cold weather [assuming the heat is turned off] I'd turn the water off and drain the pipes.
 
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Old 11-30-18, 04:03 AM
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Several years ago I put an extended length of copper pipe that went beyond the section of garage that was not walled by the house. It bust at that point. And the garage itself never got below 25 degrees.
 
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Old 11-30-18, 04:29 AM
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Like the others have said... it all depends. If the house is unheated you should open all the faucets, both hot and cold. If there is freezing it gives the pressure of the expanding ice somewhere to go without bursting the fixtures. Sponge out all the water from toilet tanks and bowls. And, remove the water from all the drain traps or pour in some RV antifreeze.
 
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Old 11-30-18, 05:28 AM
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If the house is unheated you should open all the faucets, both hot and cold. If there is freezing it gives the pressure of the expanding ice somewhere to go without bursting the fixtures.
I have to disagree with that. The copper pipes froze in my cottage one particularly brutal February and each 10-foot stick of pipe had 4-8 splits in it at random intervals of a couple inches to several feet. If "letting the pressure out" worked there would only be one split on a run of pipe.

I had to replace every inch of pipe in my crawlspace, and some verticals as well.
 
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Old 11-30-18, 06:11 AM
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it actually doesn't take long to freeze could be just a few hours but in a basement inside a house I doubt it would get that cold just from overnight lows, so it would probably take consecutive days of cold weather I would either have the water shut off and drained or atleast open the faucets to a steady dribble anyway might be just enough flow to keep them from freezing.
 
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Old 11-30-18, 06:27 AM
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On the morning of January 9th, 2004, I had an outside temperature of -48F when the power went out, From in bed, I could see own breathe.

Power came back on in about 5 hours; but it was already too late, and frost had crept into the baseboard hydronic pipes, and though I could make my boiler run, the pump couldn't push (or pull) the slushy heating fluid around past some of the cold spots . . . . no burst pipes but no movement either. Took us a full day of working with a kerosene heater in the basement and hair dryers trying to warm up the suspected problem areas.

Now, anytime I see a minor power fluctuation. my mind immediately travels back to 1/9/04. With a ΔT of over 100F, that frost can move VERY FAST !
 
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Old 11-30-18, 09:13 AM
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Guy48065, the OP said that his piping is PEX not copper. Copper is very delicate and I can't believe it's still being used. It cannot withstand any freezing and galvanized steel isn't much better. Obviously if the house will be vacant long term it's best to drain everything. For a rental that will probably only be vacant a short time and might not even freeze I don't bother draining everything, not even the water heater. With a decent number of rental properties for 20 years I've never had PEX tubing damaged by freezing. It's always been the fixtures and valves that are the problem.

Another area to watch out for is a tub/shower with a three knob faucet. After the water to the house is off open the hot and cold and... turn the middle shower diverter knob to allow the water in the shower stand pipe to drain.
 
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Old 11-30-18, 11:30 AM
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The pex is on the upper floors, the unheated/unfinished basement is where the copper pipes are.
I'm going to wrap them in insulation over the weekend.
They run alongside the upper beams so it's not possible to "wrap" the insulation around the pipe and tape it up.
Seeking recommendations to secure insulation to the wood beams that the pipes run along without building out a box along all of the piping just to secure the insulation in place.
 
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Old 12-02-18, 06:46 AM
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Yeah,
What the folks here have been saying, is that insulation is only going to delay the freezing, not prevent it. Imagine this, if you put a hot thermos of soup in a wrapped towel, it is still going to lose its heat, it is just going to take longer for the heat to escape the more insulation you put around it.

If I were you, I would find an easy way to drain and blow out the lines. You (or a plumber) could install a drain valve (or two) in the basement to the outside or even into a sink or bucket. You would then shut off the supply water. Then, with a shop vac setup to be a blower, you could open that drain valve and then go to a sink or tub upstairs and use that blower to push most of the water out of the pipes.

I don't believe they need to be completely evacuated, just enough so that when/if they freeze that the expanding ice has some space so as to not break the pipes.

Think about filling two water bottles and putting them in the freezer. Fill one to the top with water and capped with all the air out, fill the other half way with water. Now, lay them on their sides in the freezer, like a pipe. Try another one full without a cap (standing upright) to simulate what someone suggested as leaving a valve open to let the pressure escape. I'd bet a dollar to a donut the half full one fares the best.
 
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Old 12-02-18, 08:31 AM
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Just like many years ago when the milkman left milk at the front door in freezing weather.
 
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Old 12-02-18, 06:05 PM
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Heat tape that branches off?

The guy at home depot says heat tape, uninsulated, is enough to keep pipes from freezing even in an uninsulated basement.

After looking through the area I think with ropes over the pipes it can tie up the insulation successfully (just to be on the safe side).

However, the pipes tend to "branch off" in various directions,

So now the question becomes ... is there a heat tape that has branching elements so just one plug into the electrical outlet heats all the pipes?
 
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Old 12-03-18, 03:42 AM
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1st off, don't trust anything a HD depot guy tells you. Read what the specs say on the product. If you're still in doubt, call the manufacturer and ask if can be used as you intend.

Last week a customer came in and asked it heated pipe tape can be used in place of gutter heat wire. I told him I don't think it was wise to have that heat tape immersed in snow or water. I told him to call the manufacturer and I can almost bet they will say no!

As far as branching off, I don't believe pipe heat tape will allow that. However, gutter heat wire, I think does. What do the experts say about using gutter heat wire instead?
 
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Old 12-08-18, 09:40 PM
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I spent my entire day putting heat tape on all the pipes.
When I plug it in, the tape feels warm, a few minutes later it's not warm anymore.
The black circle is taped flush to the pipe as is that nub on the end.
Does the tape only heat up periodically and not stay on?
 
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Old 12-09-18, 01:43 AM
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Most heat tapes are set to come on when the temp falls to 35 above that temperature they should be off. It should state that on either the package or paperwork that came with the heat tape.
 
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Old 12-09-18, 08:43 AM
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The black circle is taped flush to the pipe...

That circle is the thermostat, it measures the temp of the pipe, not the air around it and should be wrapped with insulation.

I think you mentioned you can't wrap the pipe so it is like the old type, thermostat hangs in free air. Not sure what to think seeing this is inside a building.

One thing about that type is the thermostat must be on the coldest piece of pipe, if it's a little warmer there but colder on the other end it ain't gonna come on.

Not sure what to say, not a fan of heat tape inside a building.
 
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Old 12-11-18, 06:54 AM
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I have the black circle/termostat taped to the pipe, it's not hanging freely.
I noticed the instructions say not to overlap heat tape, it could cause a fire.
I haven't overlapped any heat tape but there are a few areas where heat tape is within in inch of another heat tape.
Should I leave those areas uninsulated so it doesn't get too hot to cause a fire?
Also is the pink standard r12 insulation flammable? There are areas where I can't get the tubing style insulation around the pipe so I'd have to stuff the pink stuff in there.
 
 

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