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Insulating Underground Pipes



 
 
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  #1  
Old October 21st 05, 10:03 PM
[email protected]
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Default Insulating Underground Pipes

I have been helping my aunt excavate her back yard, in order to expose
hot water pipes, that run about 30 feet from the house to the garage.
Both the hot water heater and the natural gas boiler are in the garage.
The pipes are not insulated and are just about 18 inches below grade,
in Cambridge, Maryland (8 feet above sea level). Last year's heating
bills were astronomical, and my Aunt thinks that a lot of heat was
radiated into the frozen ground, before it ever reached her house.

My question is, once I expose the pipes completely, what is a good
method of insulating pipes in sandy and wet soil. Cutting the pipes are
not an option, thus we need something to retrofit. The insulation must
withstand backfilling, vast temperature changes, and moisture. What can
be used on this job?

Note: The house was built in the 1940's. In addition to fixing the
pipes, my Aunt is also insulating the house's ceilings and walls.

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  #2  
Old October 21st 05, 10:21 PM
PipeDown
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Default Insulating Underground Pipes


wrote in message
oups.com...
I have been helping my aunt excavate her back yard, in order to expose
hot water pipes, that run about 30 feet from the house to the garage.
Both the hot water heater and the natural gas boiler are in the garage.
The pipes are not insulated and are just about 18 inches below grade,
in Cambridge, Maryland (8 feet above sea level). Last year's heating
bills were astronomical, and my Aunt thinks that a lot of heat was
radiated into the frozen ground, before it ever reached her house.

My question is, once I expose the pipes completely, what is a good
method of insulating pipes in sandy and wet soil. Cutting the pipes are
not an option, thus we need something to retrofit. The insulation must
withstand backfilling, vast temperature changes, and moisture. What can
be used on this job?

Note: The house was built in the 1940's. In addition to fixing the
pipes, my Aunt is also insulating the house's ceilings and walls.


Will the ground on top be subject to heavy loads like parked cars or an
occasional delivery truck or is it strictly foot traffic or garden area.

For the lighter loads I might try expanding foam mixed from a 2 part mix and
poured right on the pipes with minimal form around it to control the
expansion. May even be insulation contractors who can dispense the stuff
from a truck.

Simple closed foam (cell pipe) insulation would be better than nothing but
may compress a bit. Maybe two concentric layers.

Here is an idea: Take a piece of 4" PVC pipe and use a router to cut a slit
along it wide enough to get the hot water pipe into. Fill the pipe with
expanding foam insulation (or whatever you want) and seal the slit with
mastic or aluminum duct tape and bury slit side down.




I think you might also be able to cut a long section of 4" PVC pipe (along
the long axis or maybe just a slit wide en


  #3  
Old October 21st 05, 10:23 PM
PipeDown
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Default Insulating Underground Pipes


"PipeDown" wrote in message
. net...

wrote in message
oups.com...
I have been helping my aunt excavate her back yard, in order to expose
hot water pipes, that run about 30 feet from the house to the garage.
Both the hot water heater and the natural gas boiler are in the garage.
The pipes are not insulated and are just about 18 inches below grade,
in Cambridge, Maryland (8 feet above sea level). Last year's heating
bills were astronomical, and my Aunt thinks that a lot of heat was
radiated into the frozen ground, before it ever reached her house.

My question is, once I expose the pipes completely, what is a good
method of insulating pipes in sandy and wet soil. Cutting the pipes are
not an option, thus we need something to retrofit. The insulation must
withstand backfilling, vast temperature changes, and moisture. What can
be used on this job?

Note: The house was built in the 1940's. In addition to fixing the
pipes, my Aunt is also insulating the house's ceilings and walls.


Will the ground on top be subject to heavy loads like parked cars or an
occasional delivery truck or is it strictly foot traffic or garden area.

For the lighter loads I might try expanding foam mixed from a 2 part mix
and poured right on the pipes with minimal form around it to control the
expansion. May even be insulation contractors who can dispense the stuff
from a truck.

Simple closed foam (cell pipe) insulation would be better than nothing but
may compress a bit. Maybe two concentric layers.

Here is an idea: Take a piece of 4" PVC pipe and use a router to cut a
slit along it wide enough to get the hot water pipe into. Fill the pipe
with expanding foam insulation (or whatever you want) and seal the slit
with mastic or aluminum duct tape and bury slit side down.




I think you might also be able to cut a long section of 4" PVC pipe (along
the long axis or maybe just a slit wide en


Oops,

Simple closed foam (cell pipe) insulation
should read "Simple (closed cell) foam pipe insulation"


  #4  
Old October 21st 05, 10:51 PM
m Ransley
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Posts: n/a
Default Insulating Underground Pipes

You realy should move the boiler and water heater in the house,
seriously. You had a good suggestion with foam insulation being poured
around the pipes, but you will still loose alot of energy heating the
outside and garage. If you can`t move it inside Im guessing R 33 might
be pretty good that will equate to 6" of insulation of a foam with R 5.5
per inch rating that is a 12" form to be made. Even so you will still
loose alot of heat through the pipes and the heat the boiler itself
gives off. A great option is get a Rinnai or Takagi tankless water
heater boiler combo, you can I believe get to 93% efficiency, that is
well over the standard 80-82% of a new regular boiler, but the best part
is the heater hangs on a wall and is very very small, they can fit in a
closet. I imagine you could cut your bills in half or more with such a
system.

  #6  
Old October 22nd 05, 12:10 AM
Edwin Pawlowski
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Default Insulating Underground Pipes


"PipeDown" wrote in message
Here is an idea: Take a piece of 4" PVC pipe and use a router to cut a
slit along it wide enough to get the hot water pipe into. Fill the pipe
with expanding foam insulation (or whatever you want) and seal the slit
with mastic or aluminum duct tape and bury slit side down.


Good idea. Use the spray in foam. It gets hard enough and will stay in
position so you'd not have to put the slit down. Sure would give plenty of
insulation.


  #8  
Old October 22nd 05, 12:40 AM
Chris Lewis
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Default Insulating Underground Pipes

According to PipeDown :

Will the ground on top be subject to heavy loads like parked cars or an
occasional delivery truck or is it strictly foot traffic or garden area.


For the lighter loads I might try expanding foam mixed from a 2 part mix and
poured right on the pipes with minimal form around it to control the
expansion. May even be insulation contractors who can dispense the stuff
from a truck.


Styrofoam SM (the blue stuff) is often used in direct burial applications.

Ie: under slabs, on foundation outside faces, etc.

I would assume it could withstand the temperatures involved here.
[It's used in contact with radiant flooring.]

I suggest it because it's probably easier/cheaper than on-site
mixing/installation of foam for a DIY.

If suitable, I'd recommend putting several inches of gravel, then
two 8" wide layers of 2" foam, a slot for the pipes, and another
two layers of 2" foam. Glue the layers/"joints" together with foam adhesive
(available as a caulking tube).

A 2'x8' slab of foam is around $15 IIRC. That would do about
12 linear feet of insulation (8"x8"). What is that anyway? 4" of foam
is R20, right?

Wrap it with tape to keep it from shifting if the glue is still wet,
and you're backfilling.

Even at only a foot down, it should withstand considerable surface
traffic, but to be absolutely sure, fling on a few treated 1x6 fence
planks before backfilling. Even strips of exterior grade OSB would do.
[It'll eventually rot out, but by then the soil will be compact enough
to not crush the foam.]

A building supply house that's "advanced enough" to know and supply
the various grades of SM available (ie: under slab vs. interior wall
etc) would be able to advise you which grade is right for this, or whether
this is a dumb idea.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
  #9  
Old October 22nd 05, 12:55 AM
w_tom
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Default Insulating Underground Pipes

18 inches is not sufficient for any pipes with water. Pipes
typically should be 3 feet under for reliability, human
safety, and pipe protection (even from rodents) as well as to
insulate the pipes. Insulation only 18 inches down makes a
perfect nest for rodents. Pipes should also be installed so
that if the heat is turned off, pipes will not freeze. 18
inches is not sufficient for electric wires feeding the
building. Why then would it be acceptable for heat pipes?

Meanwhile, if 6 inches of insulation was not sufficient for
the house, then why would anything less be sufficient for
pipes that are even hotter? Let's assume those pipes have 6
inches of insulation. That means less than 1 foot of dirt?
To be effective, the insulation must not compress which is
another reason why the pipes should be deeper - not subject to
compression forces of overhead traffic only 1 foot away.

wrote:
I have been helping my aunt excavate her back yard, in order to expose
hot water pipes, that run about 30 feet from the house to the garage.
Both the hot water heater and the natural gas boiler are in the garage.
The pipes are not insulated and are just about 18 inches below grade,
in Cambridge, Maryland (8 feet above sea level). Last year's heating
bills were astronomical, and my Aunt thinks that a lot of heat was
radiated into the frozen ground, before it ever reached her house.

My question is, once I expose the pipes completely, what is a good
method of insulating pipes in sandy and wet soil. Cutting the pipes are
not an option, thus we need something to retrofit. The insulation must
withstand backfilling, vast temperature changes, and moisture. What can
be used on this job?

Note: The house was built in the 1940's. In addition to fixing the
pipes, my Aunt is also insulating the house's ceilings and walls.

 




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