How much insulation on exposed water supply pipe

[fritz]

I can't seem to find a guide on this online.  I have my water supply line buried 5 feet deep and then it (unfortunately) has a 3 feet vertical exposed section between the ground and the cabin floor.  I wrapped it in 3 thicknesses of foam pipe wrap as a test to see if that would prevent freezing and somewhere around 10 degrees, it froze.  My supply line is Zurn Pex -- so no damage.

For this season, I've added a Heat tape -- first wrapping the Pex in aluminum foil, then the straight tape, thermostat touching the foil covered pipe, and then wrapped the pipe and tape in one inch fiberglass insulation.  But I dont want to run a heat tape all winter and not next year for sure.  So

Any suggestions or tables on a needed R value around pipe?

[Jochen]

How deep into the ground did you went with your insulation around the pipe? Keep in mind that the ground will feeze as well, therefore your buried pipe then as well. When I remember correctly I went one feet deep with insulation material and added a heat tape. I then built a case around the pipe to keep wind out. For the heat tape, it is easy peace of mind. Only a few dollars for our six month winter period.

Jochen

[ScottA]

I use a heat tape plus 2" of insulation. Heat tape can melt plastic pipe so I'd suggest a copper riser. I don't know if the foil will work, maybe.

[fritz]

Thanks, the foam insulation covered the pex riser down to water the burried waterline -- so 5 feet give or take.  I've left that foam in place but now that I think, it is only one thickness so maybe 1/2 inch.

Scott, I hear you on copper riser -- but my thought with pex were IF it froze, it was not likely to split or burst.  PEX does need to be shielded from sunlight -- so initially I went with the foam.

Sounds like consensus is heat tape.....

[lobster]

insulation works by keeping internal heat from being dissipated away to the surroundings (assuming surroundings are cooler than the unfrozen water in the pipe.)

of course the water as drawn from the well deep underground is warmer than freezing (that is the heat i am referring to), and once the pipe gets inside your house the surroundings are above freezing, but the air under the floor (crawl space) and the soil close to the surface (above the frost line) whch the supply pipe is buried in can both be below freezing - and that is where the danger lies for the pipe losing its heat to surroundings.

i had the same situation.  they way i figure it, any sort of contact with the ground (where the feeder pipe is buried) and above ground (in the freezing crawl space) should be minimized.  so just where the supply line comes up from buried and into the house (which happens to be right under my kitchen sink) i installed a 3" schedule 40 pipe through a toilet flange on the floor under the sink, and this 3" pipe goes below ground to below the frost line.  the supply line sort of sits in the center of this larger pipe and is thus isolated from the freezing soil and from any winds in the crawl space.

i did also put plastic foam around the supply pipe and applied a heat tape to it, but i figure since the 3" pipe is open at the top, the (relatively) hot air inside the house will cause an environment around the supply pipe that will be warmer than either the crawlspace air or the above-frostline earth.

[Mike 870]

In the Do it Yourself Home Building Book by Nash (linked off the suggested reading on this site), he goes over a couple strategies for this.  He talks about the tape, but mentions it has a nasty habit of burning out and can also be a fire hazard if installed improperly.  Another strategy is a hot box type of area, insulated down to below the frost line, and heated with a 60 or 100 watt bulb or a vent to allow heat from your house down into the boxed off compartment.  I'm going from memory here so you may want to consult the book.

[rwanders]

I am using a different strategy to avoid frozen supply line from well to cabin. My pressure tank includes a "bleed back valve" that will allow the line to bleed back to the well casing after the pressure tank has been refilled---the only time the line has water in it is while the well pump is running. This method is fairly common here in southcentral Alaska. Winter temperatures at my cabin in Willow, Alaska will often go down to -30 or even colder at times.

[lobster]

if the water drains out of the supply pipe after each time the pump runs to fill the pressure tank, the next time the pump has to run doesn't that charge the tank with a little air, and so make it air bound after a while, with lots of spluttering and splashing when the water runs out of the faucets?

[glenn kangiser]

Some pumps work that way - the ones that do not use a bladder tank as the primary water tank.  They have an air release valve in them - a float and gauge combo along with an excess air bleed - they work by bleeding down the water to replenish the air in the tank.  There is a springless Shrader valve above ground and a bleed down valve in the well 10 feet or so down.

[hnash53]

Pile a bunch of wood chips, perhaps a foot deep and 2 feet out around where the pipe goes into the ground.  That will keep the ground from freezing.  The wood chips act like insulation and keep the ground from freezing.  I've used wood chips to insulate my foundation at 8000 feet elevation in Wyoming and it's not moved at all in 7 years.

People who grow potatoes can harvest them year round by putting grass clippings over where the potatoes are still in the ground.  It can be way below zero in the air, but with the grass clippings over the potatoes, they don't freeze.  Same principle would work where your pipe goes into the ground.

[NM_Shooter]

You have to have a heat source of some kind to keep the pipe from freezing.  No amount of insulation will protect you if you don't do one of the following:

1)  You can either keep the water moving in the pipe.
2)  Keep the temperature near the pipe above freezing.
3)  Drain the pipe completely after using each time.

All insulation does is slow down heat transfer.  If you don't run your water, or you don't heat it, sooner or later your pipes will freeze. 

You can use heat from the earth if you allow for conduction / convection, but that would require a pretty good amount of effort / material. 

Good luck!

[Taylor]

i had the same situation.  they way i figure it, any sort of contact with the ground (where the feeder pipe is buried) and above ground (in the freezing crawl space) should be minimized.  so just where the supply line comes up from buried and into the house (which happens to be right under my kitchen sink) i installed a 3" schedule 40 pipe through a toilet flange on the floor under the sink, and this 3" pipe goes below ground to below the frost line.  the supply line sort of sits in the center of this larger pipe and is thus isolated from the freezing soil and from any winds in the crawl space.

I like that idea, I might have to try that. I wonder if you filled it with pea gravel or sand or something like that to help make a thermal mass around the inner pipe if it would make it better.

Taylor

[lobster]

i don't think it's a good idea to fill with anything.  as nm_shooter points out, no amount of insulation alone will keep water from freezing unless it is running (and so constantly refreshed by above-freezing water from deep in the well.)

the idea is to somehow get heat down there to prevent still water from freezing.  the "free" heat from inside the house does the trick in my installation since the pipe is open to the house at the top.  but if the pipe were filled with something that would not be the case.

[Taylor]

I have a 550g water tank I get my water from, I fill it up with the neighbor's well once a week or so. I know this will only help people with a water tank, but the way I keep my water from freezing; is I have a hose fitting plumbed into the top of the tank so I have a hose from my trailer running to the top of my tank and leave it running slowly so it keeps everything from freezing and helps keep the water fresh. When I get my house done, I plan to hard plumb a return back so I don't have a hose running across the yard, until I can get a well.

Taylor

[fritz]

More on this thread.... I found this Missouri Extension article on the heat tape necessary to heat various water supply lines:

http://extension.missouri.edu/explore/agguides/agengin/g01408.htm

For example, a 3/4" diameter exposed pipe at 10 below needs 12.3 watts per foot

If the pipe is also insulated with 1 inch insulation, it needs 3.7 watts per foot.

I hope this helps others.

[bayview]

  I had a similar problem when living in a mobile home in Minnesota. 

   We built an insulated box around the pipe.  Between the ground and the mobile home.  And put a light bulb inside.  The heat of the bulb was enough to keep it from freezing.