The humid weather is resulting in "sweaty" cold water pipes in our
basement.

I have read the suggestion to insulate the pipes just like with hot
water pipes. However, I am concerned that while this may reduce the
sweating, there still will be some condensation, but now the
condensation will be trapped against the pipe.

Should I be worrying about this? If so, what should I do to minimize
the potential for mildew and mold in this trapped moisture?

Second, I find that the condensation only occurs on the first few feet
of pipe in from the grounde. Is it possible that conduction causes the
water in the first few feet of pipe to stay cold all the time leading
to heavy condensation while beyond that the water for the most part
has warmed up (except when the water is actively running) so that
there is much less active condensation?

"blueman" wrote in message

I have read the suggestion to insulate the pipes just like with hot
water pipes. However, I am concerned that while this may reduce the
sweating, there still will be some condensation, but now the
condensation will be trapped against the pipe.

Insulated properly there will be no condensation to trap.



Should I be worrying about this?

No



Second, I find that the condensation only occurs on the first few feet
of pipe in from the grounde. Is it possible that conduction causes the
water in the first few feet of pipe to stay cold all the time leading
to heavy condensation while beyond that the water for the most part
has warmed up (except when the water is actively running) so that
there is much less active condensation?

Yes, but if you run a lot of water it will move along the line as it cools
down. Depends on your particular use, temperatures, humidity, etc.

Pawlowski is, again, correct.
The water on the pipe surface comes from the air.
Thus, a well sealed insulation jacket will not allow moisture to fomr
on the pipe.
TB

wrote:

...a well sealed insulation jacket will not allow
moisture to fomr on the pipe.

And it may increase the water heating bill.

Nick

blueman wrote:
The humid weather is resulting in "sweaty" cold water pipes in our
basement.

I have read the suggestion to insulate the pipes just like with hot
water pipes. However, I am concerned that while this may reduce the
sweating, there still will be some condensation, but now the
condensation will be trapped against the pipe.


Well I heard this insulation was primarily for the cold water pipe, not
the hot water pipe.


--
Respectfully,


CL Gilbert

I have it on my cold water line, no problems

"CL (dnoyeB) Gilbert" wrote in message
...
blueman wrote:
The humid weather is resulting in "sweaty" cold water pipes in our
basement.

I have read the suggestion to insulate the pipes just like with hot
water pipes. However, I am concerned that while this may reduce the
sweating, there still will be some condensation, but now the
condensation will be trapped against the pipe.


Well I heard this insulation was primarily for the cold water pipe, not
the hot water pipe.


--
Respectfully,


CL Gilbert

wrote:
wrote:

...a well sealed insulation jacket will not allow
moisture to fomr on the pipe.

And it may increase the water heating bill.

Nick

Not in any measurable way. I assume you are meaning the heat the cold
water picks up in the line while waiting for some draw. It is minimum.
Even a few degrees rise in a pipe run of 40 ft doesn't add up to a
sneeze.

Harry K

Harry K wrote:

wrote:

wrote:

...a well sealed insulation jacket will not allow
moisture to fomr on the pipe.

And it may increase the water heating bill.

Not in any measurable way...

I disagree.

Nick

wrote:
Harry K wrote:

wrote:

wrote:

...a well sealed insulation jacket will not allow
moisture to fomr on the pipe.

And it may increase the water heating bill.

Not in any measurable way...

I disagree.

Nick

Care to expound on why? The amount of water contained in a 3/4" pipe
say 20 ft long is not very much. About 5 cu in/ft (after heavy
rounding off) unless my long ago math is out of whack. Water in the
cold intake pipe also doesn't usually sit there long enough to pick up
much ambient heat.

Harry K

writes:
Pawlowski is, again, correct.
The water on the pipe surface comes from the air.
Thus, a well sealed insulation jacket will not allow moisture to fomr
on the pipe.
TB

How well sealed is "well sealed"?
Is it enough to buy the Home Chepot middle-grade stuff that comes with
taped edges that you push together?

My sense is that the adhesive tape is enough to keep it on the pipe but not
enough to make a real seal.
Is there stuff that is better to buy or should I cover the seam with
something like duct tape?

Thanks

"blueman" wrote in message
...
writes:
Pawlowski is, again, correct.
The water on the pipe surface comes from the air.
Thus, a well sealed insulation jacket will not allow moisture to fomr
on the pipe.
TB

How well sealed is "well sealed"?
Is it enough to buy the Home Chepot middle-grade stuff that comes with
taped edges that you push together?

As long as it holds, yes.

My sense is that the adhesive tape is enough to keep it on the pipe but
not
enough to make a real seal.

If you have concerns wrap some tape every 12" or so. Duct tape or
electrical tape will work. Mine has b een holding for about 20 years, but
that does not mean what you buy today will.

In alt.home.repair on Fri, 22 Jul 2005 01:32:04 GMT blueman
posted:

writes:
Pawlowski is, again, correct.
The water on the pipe surface comes from the air.
Thus, a well sealed insulation jacket will not allow moisture to fomr
on the pipe.
TB

How well sealed is "well sealed"?
Is it enough to buy the Home Chepot middle-grade stuff that comes with
taped edges that you push together?

My sense is that the adhesive tape is enough to keep it on the pipe but not
enough to make a real seal.
Is there stuff that is better to buy or should I cover the seam with
something like duct tape?

Thanks

If you put it on when the pipe is dry, almost anything will keep the
humid air from touching the pipe after that. No humid air, no
condensation. If part of the pipe is dry, wipe it off with a towel
first.

Personally, I doubt mold or anything will grow on a little dampness on
a copper pipe, but this should prevent any.

If youre still not sure, open part up after 6 months and check it out.
But you have to look right away. The moment you open it up, humid air
might start to condense on the pipe.

Meirman
--
If emailing, please let me know whether
or not you are posting the same letter.
Change domain to erols.com, if necessary.

Harry K wrote:

wrote:

...a well sealed insulation jacket will not allow
moisture to fomr on the pipe.

And it may increase the water heating bill.

Not in any measurable way...

I disagree...

Care to expound on why? The amount of water contained in a 3/4" pipe
say 20 ft long is not very much. About 5 cu in/ft...

I get 0.19 lb/ft, so 20' would hold 3.8 pounds.

...Water in the cold intake pipe also doesn't usually sit there long enough
to pick up much ambient heat.

That depends on how fast the heat flows... 20' of 3/4" pipe has about
4 ft^2 of surface. With still air and no condensation, it might have
a thermal conductance G = 1.5x4 = 6 Btu/h-F, so the time constant RC
= C/G = 1 hour, ie a 3.8 lb slug of water would warm from 50 to about
57 F (1/e th of the way to 70) in 1 hour in a 70 F room.

Recall Charlie Wing's TV show in which he built a tempering tank in
a basement, a 20' length of 6" PVC pipe tucked up under the rafters?
Well pressure tanks can warm water too.

And condensation might raise G to 1000, so flowing water can warm to
the dew point in real time as it moves along the pipe. As I recall,
the OP described "a few feet" of condensation near the pipe entrance.
I don't recall that the entire pipe had condensation when water was
flowing. If not, the pipe warmed flowing cold water to the dew point.

With no cold water pipe insulation, we have 4 potential savings in
water heating: the small warm slug of still water before flow begins,
the large flowing gain to the dew point, the small flowing gain from
the dew point to room air, and the effect of having warmer cold water
at a sink or a shower, which can allow using less hot water in a mix
to achieve a certain temperature. The latter may come from a lot more
cold water pipe in the house, unrelated to the pipe that goes into
the water heater. Harvard physicist William Shurcliff has written
about these savings.

Nick

wrote:
Harry K wrote:

wrote:

...a well sealed insulation jacket will not allow
moisture to fomr on the pipe.

And it may increase the water heating bill.

Not in any measurable way...

I disagree...

Care to expound on why? The amount of water contained in a 3/4" pipe
say 20 ft long is not very much. About 5 cu in/ft...

I get 0.19 lb/ft, so 20' would hold 3.8 pounds.

...Water in the cold intake pipe also doesn't usually sit there long enough
to pick up much ambient heat.

That depends on how fast the heat flows... 20' of 3/4" pipe has about
4 ft^2 of surface. With still air and no condensation, it might have
a thermal conductance G = 1.5x4 = 6 Btu/h-F, so the time constant RC
= C/G = 1 hour, ie a 3.8 lb slug of water would warm from 50 to about
57 F (1/e th of the way to 70) in 1 hour in a 70 F room.

Recall Charlie Wing's TV show in which he built a tempering tank in
a basement, a 20' length of 6" PVC pipe tucked up under the rafters?
Well pressure tanks can warm water too.

And condensation might raise G to 1000, so flowing water can warm to
the dew point in real time as it moves along the pipe. As I recall,
the OP described "a few feet" of condensation near the pipe entrance.
I don't recall that the entire pipe had condensation when water was
flowing. If not, the pipe warmed flowing cold water to the dew point.

With no cold water pipe insulation, we have 4 potential savings in
water heating: the small warm slug of still water before flow begins,
the large flowing gain to the dew point, the small flowing gain from
the dew point to room air, and the effect of having warmer cold water
at a sink or a shower, which can allow using less hot water in a mix
to achieve a certain temperature. The latter may come from a lot more
cold water pipe in the house, unrelated to the pipe that goes into
the water heater. Harvard physicist William Shurcliff has written
about these savings.

Nick

Good discussion of the -theorectical- savings. Just how much savings
dollar wise do you think it comes down to in practical life? You won't
see it on your power bill. Most of your warming is coming from having
water stand still in the pipe for long periods. That doesn't happen in
an active house. The tempering tank could have some small advantage. I
wonder about the well tank (basically same as tempering tank). Think I
will test my incoming water temp as opposed to the tank out temp after
sitting all night.

Harry K

Harry K

Harry K wrote:

With no cold water pipe insulation, we have 4 potential savings in
water heating: the small warm slug of still water before flow begins,
the large flowing gain to the dew point, the small flowing gain from
the dew point to room air, and the effect of having warmer cold water
at a sink or a shower, which can allow using less hot water in a mix
to achieve a certain temperature. The latter may come from a lot more
cold water pipe in the house, unrelated to the pipe that goes into
the water heater. Harvard physicist William Shurcliff has written
about these savings...

Good discussion of the -theorectical- savings. Just how much savings
dollar wise do you think it comes down to in practical life?

The biggest might be from condensation on active pipes. If we spend
(say) 50K Btu/day warming 1000 pounds of 60 F well water to 110 in
a water heater, and insulating the cold water pipes lowers the 60
to 50, we have to spend 1000(110-50) = 60K Btu/day, ie 20% more, eg
10K/3412 = 2.93 kWh/day or 1070 kWh/year, eg $107 at 10 cents/kWh.

You won't see it on your power bill...

I disagree.

Nick

Nick, according to my calculations, there 5.3 cubic inches of water in
a foot of pipe, that is equal to .0229 gallons. At 8.33 pounds per
gallon, that is .191 pounds of water per foot of pipe. Assume 10 feet
of 3/4" pipe that sweats that is 1.91 pounds of water. To warm that
from 40 degrees incoming temperature to 70 degrees, at 1 BTU times 30
degrees times 1.91 pounds = 57.3 BTUs. At 8 cents per therm (100,000
BTUs) the cost savings gained by leaving the insulation off is.0045
cents every time you have to warm the water in the pipe. If the people
in the house use the water 40 times each day, the total savings per day
is .183 cents per day. Times 30 days per month is 5.49 cents (per
month). Nick, that is not enough to worry about. Even if you allow
for inefficiencies, it is still less than 10 cents per month. Nick,
that is not worth the time I just spent on it. Or do I need to write
that into a BASIC program to get the point across to you?

Stretch

Stretch wrote:
Nick, according to my calculations, there 5.3 cubic inches of water in
a foot of pipe, that is equal to .0229 gallons. At 8.33 pounds per
gallon, that is .191 pounds of water per foot of pipe. Assume 10 feet
of 3/4" pipe that sweats that is 1.91 pounds of water. To warm that
from 40 degrees incoming temperature to 70 degrees, at 1 BTU times 30
degrees times 1.91 pounds = 57.3 BTUs. At 8 cents per therm (100,000
BTUs) the cost savings gained by leaving the insulation off is.0045
cents every time you have to warm the water in the pipe. If the people
in the house use the water 40 times each day, the total savings per day
is .183 cents per day. Times 30 days per month is 5.49 cents (per
month). Nick, that is not enough to worry about. Even if you allow
for inefficiencies, it is still less than 10 cents per month. Nick,
that is not worth the time I just spent on it. Or do I need to write
that into a BASIC program to get the point across to you?

Stretch

Thanks. My last physics was in HS 50 years ago. I was beginning to
think I'd have to do some real research to make the point. I was
running off of common sense and practical application. There are a lot
of things out there that look good in theory but don't work out in
practical application. Of course Nick can argue that any savings is
worth it but to me dripping pipes trumps that one.

Harry K

Common sense and practical application don't seem to apply with Nick.
His math may be correct, but his assumptions often go awry. He has
some interesting points, but if he had customers that had to live with
his assumptions, he would soon go broke.

Stretch

Stretch wrote:

Nick, according to my calculations, there 5.3 cubic inches of water in
a foot of pipe, that is equal to .0229 gallons. At 8.33 pounds per
gallon, that is .191 pounds of water per foot of pipe.

We all seem to agree on that.

Assume 10 feet of 3/4" pipe that sweats that is 1.91 pounds of water.

And that...

To warm that from 40 degrees incoming temperature to 70 degrees, at
1 BTU times 30 degrees times 1.91 pounds = 57.3 BTUs.

Yes...

At 8 cents per therm (100,000 BTUs)...

You can buy oil for 8 cents a gallon? :-)

the cost savings gained by leaving the insulation off is.0045 cents
every time you have to warm the water in the pipe.

I make this 0.115 cents at $2/gallon.

If the people in the house use the water 40 times each day, the total
savings per day is .183 cents per day...

And 4.6 cents/day.

Times 30 days per month is 5.49 cents (per month)...

And $1.37/month.

Nick, that is not enough to worry about. Even if you allow for
inefficiencies, it is still less than 10 cents per month. Nick,
that is not worth the time I just spent on it. Or do I need to write
that into a BASIC program to get the point across to you?

You might check your math for glaring errors and read more carefully.
I said this savings is small compared to warming an active pipe with
condensation, which might save 20% on a water heating bill.

And you might modify your arrogant attitude and be more polite.

Apologizing is optional.

Nick

Nick,
You assumed oil heating the water, I assumed gas. Although my gas
rates may be off a bit, he did not say what he is heating the water
with. Also the calculations assume the water is completely warmed to
room temperature each time, which is not likely. There are a lot of
suppositions involved here, most of them are overblown. The daily
savings are likely exagerated to the extreme. Also, pipe insulation
slows down the rate of heat transfer and increases the area of surface
area exposed to ambient conditions. It does not stop heat transfer.
As well, as the temperature in the pipe approaches room temperature of
the basement, heat transfer slows down, so it will take too long for
all this heat transfer to tane place. Certainly each complete
temperature change is not likely to take place in in 36 minutes. So an
apology is not likely. Still not enough cost to worry about.

Stretch

Stretch wrote:
Nick,
You assumed oil heating the water, I assumed gas. Although my gas
rates may be off a bit, he did not say what he is heating the water
with. Also the calculations assume the water is completely warmed to
room temperature each time, which is not likely. There are a lot of
suppositions involved here, most of them are overblown. The daily
savings are likely exagerated to the extreme. Also, pipe insulation
slows down the rate of heat transfer and increases the area of surface
area exposed to ambient conditions. It does not stop heat transfer.
As well, as the temperature in the pipe approaches room temperature of
the basement, heat transfer slows down, so it will take too long for
all this heat transfer to tane place. Certainly each complete
temperature change is not likely to take place in in 36 minutes. So an
apology is not likely. Still not enough cost to worry about.

Stretch

Even using Nicks figures there is a glaring assumption that way
inflates the figures. Although you did point it out, I will do so
again. Water in the intake pipe is -not- going to warm up to ambient
in less than several hours. In my house with just the two of us, water
in that pipe will only remain there until the pump kicks in again.
Given normal useage that will occur at least once per hour, oftener
when watering. In a house on city supply, there will be an exchange of
water in that pipe any time a faucet is opened or toilet flushed, etc.
That will occur several times/hour for zero savings.

I am on oil for heat, electric for water heating.

Harry K

Stretch wrote:

Nick,
You assumed oil heating the water, I assumed gas. Although my gas
rates may be off a bit...

A factor of 10, but that was the UNportant savings...

Also the calculations assume the water is completely warmed to
room temperature each time...

No. Please reread them more carefully.

Nick

Harry K wrote:

Even using Nicks figures there is a glaring assumption that way
inflates the figures. Although you did point it out, I will do so
again. Water in the intake pipe is -not- going to warm up to ambient
in less than several hours.

There was no such assumption.

The important savings happens when flowing water is completely warmed
to the dew point by condensation in real time.

Nick

Nick, If gas is that expensive in your area, maybe you should move
here! :-)

Stretch

Stretch wrote:
Nick,
You assumed oil heating the water, I assumed gas. Although my gas
rates may be off a bit...


A factor of 10, but that was the UNportant savings...


Also the calculations assume the water is completely warmed to
room temperature each time...


No. Please reread them more carefully.

Nick


OK Nick, you got me on this one! I WAS off by a factor of 10 on my gas
costs. Please pass the salt with the crow!

CHEW, CHEW, CHEW, CHEW, ..... Boy, this stuff is tough!

Stretch

CHEW, CHEW, CHEW, CHEW....................

Stretch wrote:

...my gas rates may be off a bit...

A factor of 10, but that was the UNimportant savings...

OK Nick, you got me on this one! I WAS off by a factor of 10 on my gas
costs. Please pass the salt with the crow!

CHEW, CHEW, CHEW, CHEW, ..... Boy, this stuff is tough!

:-)

Now you might ask yourself what's really going on he

The humid weather is resulting in "sweaty" cold water pipes in our
basement...

...***I find that the condensation only occurs on the first few feet
of pipe in from the ground*** Is it possible that conduction causes the
water in the first few feet of pipe to stay cold all the time leading
to heavy condensation while beyond that the water for the most part
has warmed up...?

I think the OP is saying the incoming water is warming up to the dew point
of the basement air. If condensation never occurs beyond the first few feet
of pipe, even when water is flowing, the pipe is warming flowing water in
real time, which is a much more important saving than the warming of small
amounts of water between uses.

Nick

wrote:

snip

:-)

Now you might ask yourself what's really going on he

The humid weather is resulting in "sweaty" cold water pipes in our
basement...

...***I find that the condensation only occurs on the first few feet
of pipe in from the ground*** Is it possible that conduction causes the
water in the first few feet of pipe to stay cold all the time leading
to heavy condensation while beyond that the water for the most part
has warmed up...?

I think the OP is saying the incoming water is warming up to the dew point
of the basement air. If condensation never occurs beyond the first few feet
of pipe, even when water is flowing, the pipe is warming flowing water in
real time, which is a much more important saving than the warming of small
amounts of water between uses.

Nick

Do you -really- think that water coming in at 50 degrees (IINM that is
about normal underground temp) at high velocity, at least that of an
open fixture, is going to pick up much useable heat in 10 ft?

I suspect he is referring to non-flowing conditions. I kind of lost
track here. Does he say that it is in a basement? In my case it is
and the pipe is coated with condensate from the point it enters until
it disappears into the ceiling joists. Temp in my basement is around
65, too cool to sit down there in a t-shirt.

Harry K

Harry K

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 23 Jul 2005 15:25:54 -0700, "Stretch"
wrote:

OK Nick, you got me on this one! I WAS off by a factor of 10 on my
gas costs. Please pass the salt with the crow!

CHEW, CHEW, CHEW, CHEW, ..... Boy, this stuff is tough!

Whaddya expect, this is FEAR FACTOR.


-----BEGIN PGP SIGNATURE-----
Version: PGP 7.1

iQA/AwUBQuMcEwIk7T39FC4ZEQKcogCgpEn+q3JwguFLfzA/yy5Qib+Zmn0AoKEJ
c0wugpq6j2GD6jvHOC3ea+IY
=7Irh
-----END PGP SIGNATURE-----

--
-john
wide-open at throttle dot info

Harry K wrote:

Now you might ask yourself what's really going on he

The humid weather is resulting in "sweaty" cold water pipes in our
basement...

...***I find that the condensation only occurs on the first few feet
of pipe in from the ground*** Is it possible that conduction causes the
water in the first few feet of pipe to stay cold all the time leading
to heavy condensation while beyond that the water for the most part
has warmed up...?

Do you -really- think that water coming in at 50 degrees (IINM that is
about normal underground temp) at high velocity, at least that of an
open fixture, is going to pick up much useable heat in 10 ft?

Sure, based on the OP's description and the fact that condensation can
dramatically increase the air-to-pipe thermal conductance by a factor of
100 or more... 2 gpm is 960 Btu/h-F, so warming it 1 F takes 960 Btu/h, ie
1 pint of condensation per hour, about 3 drops per second. I can imagine
that, in continuous use, altho most usage bursts are a lot shorter.

It might make sense to change this pipe to fin-tube vs insulating it :-)

Nick

if you leave the pipe uninsulated you will avoid the killer mold in the
insulation problem, which is what you probably heard about on tv news
last year. a spray-on aerosol can foam insulation would ease your mold
worries if you insist on insulation. check with your local building
inspector for requirements and ideas.

"Harry K" writes:
wrote:

snip

:-)

Now you might ask yourself what's really going on he

The humid weather is resulting in "sweaty" cold water pipes in our
basement...

...***I find that the condensation only occurs on the first few feet
of pipe in from the ground*** Is it possible that conduction causes the
water in the first few feet of pipe to stay cold all the time leading
to heavy condensation while beyond that the water for the most part
has warmed up...?

I think the OP is saying the incoming water is warming up to the dew point
of the basement air. If condensation never occurs beyond the first few feet
of pipe, even when water is flowing, the pipe is warming flowing water in
real time, which is a much more important saving than the warming of small
amounts of water between uses.

Nick

Do you -really- think that water coming in at 50 degrees (IINM that is
about normal underground temp) at high velocity, at least that of an
open fixture, is going to pick up much useable heat in 10 ft?

I suspect he is referring to non-flowing conditions. I kind of lost
track here. Does he say that it is in a basement? In my case it is
and the pipe is coated with condensate from the point it enters until
it disappears into the ceiling joists. Temp in my basement is around
65, too cool to sit down there in a t-shirt.

Harry K

Harry K

OK -- I am the OP, so let me clarify some points.
1. Yes, the condensation only appears on the first 6 feet or so of the
1" pipe. That pipe runs vertically near the basement wall where the
city supply enters. The 1" pipe is pretty dry after it turns
horizontal and continues to be dry as it branches off to the water
heater and converts down and branches to 1/2" pipe runs for the house
cold water supply.

About 1/3 up the initial vertical 1" pipe run, the 1" pipe bifurcates
to supply the underground sprinkler system. This bifurcated pipe rises
in parallel with the rest of house supply for about 3 ft and then
exits the house. This run also "sweats" heavily.

My initial thought was that the 2 hour runs of the sprinkler may be
primarily responsible for the sweating. However, I have not noticed
significant variability in the condensation between days (and times)
that the sprinkler runs vs. when it doesn't.

Also, the rest of house supply pipe continues to have heavy condensate
for 2-3 feet above where the sprinkler branches.

Also, btw, we heat the hot water with gas and we live in New England.

Finally, last night I insulated the first 10 feet or so of the 1" runs
(except around the valves and water meter), plus the branch to the
sprinkler system.

We will see what happens (though today is significantly less humid so
it may not give it a good test).