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Old 10-09-2011, 09:51 PM   #31
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i wouldnt use cheap foam on boiler lines.
Do you say that because you believe it's inferior due to its price relative to other materials, or because you have some other knowledge of it?

I apologize if that comes across wrong, I appreciate all opinions, I'm just trying to figure out if this just your gut feeling, or because you know something about it.

Also, I am using fiberglass pipe wrap on all the main first floor heating lines that are 1-1/4" and 1-1/2", because they are too large for foam. The exception being the 1/2" iron pipes that break off the main lines to feed the individual convectors. For the second floor it's 3/4" copper, they don't have any of the fiberglass that small, and in addition the pipe runs very tight to the joists, I can just barely get the foam slipped over it as is, FG would never work.

As for fire hazard... I'll be honest, I'm not that worried about that. Even assuming the boiler somehow malfunctioned and managed to heat up to say 240*, that is well below ignition point for anything, and if I have flames near this foam I have bigger problems.

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Old 10-09-2011, 10:13 PM   #32
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BTW, the reason to do this in my opinion is two-fold:

1) Reduce fuel use (get more heat to the baseboards/convectors and faster hot water to the taps). In addition to the pipe insulation, I'm learning more about my system, next summer I will definitely plan to lower the aquastat low/high limits. There was no reason to keep it set to 180/200*F this past summer, I could have easily gotten away with 150/170* for domestic hot water.

2) Increase comfort ... if my convectors are averaging 140* w/o insulation, I might see 150* with, because there is nearly 150' of black pipe down there... on a cold day my cats press themselves against the basement door because the basement is actually staying warmer with all those pipes exposed then the first floor. I also have a ~30' run from my boiler to the bathroom taps and ~20' to the kitchen taps. By insulating those pipes I keep the slug of water in them hotter for a longer period, the result is potentially faster use of the water instead of waiting for a gallon or so of cold/warm water to flow before the hot stuff gets there.
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Old 10-09-2011, 11:53 PM   #33
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Nothing to do with the price. Sometimes it gets knocked around under a house, and gets too close to a halogen light, and it basically disintegrates from the heat.

The cheap open cell foam insulation is not intended for high temp applications.
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Old 10-10-2011, 07:42 AM   #34
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Nothing to do with the price. Sometimes it gets knocked around under a house, and gets too close to a halogen light, and it basically disintegrates from the heat.

The cheap open cell foam insulation is not intended for high temp applications.
It's a good point, but a halogen bulb is going to be at least 2-3X hotter than the boiler pipes (Halogen Bulbs, looks like 250*C to 600*C).

Looking again, I see they do have the fiberglass insulation for 1/2" and 3/4" pipes listed on their website, I must have missed it in the store. It's 8-9X more expensive per foot than the foam, but if it will be safer (for work lights, future torch plumbing repairs, etc) it's worth it.
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Old 10-24-2011, 05:18 PM   #35
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Your forum popped up in response to my simple Google query, “what is the r value of pipe insulation”. I’m surprised that there seemed to be no mention or reference to the FTC’s R-Value Rule, http://www.ftc.gov/bcp/rulemaking/rvalue/index.shtml , the ASTM (American Society for Testing and Materials) International C680-10, http://www.astm.org/Standards/C680.htm , or even Wikipedia’s page, http://en.wikipedia.org/wiki/Pipe_insulation , where it states, “R-values of pipe insulation are not covered by the US FTC R-value rule”. Those interested in flammability issues might benefit from reading “Flammability of Plastics and Polymers…” (Paul A Kittle, Ph.D., April, 1993), www.aquafoam.com/papers/flammability.pdf . Having said all that, I found this helpful generalized site: “Insulating Your Hot Water Pipes…”. Having been in maintenance for over 25 years, I realize that there is a difference between the technical information that we should understand, and the simplified (kiss), condensed version that we must convey to management, customers, and personality-type A’s. It’s your decision. -William
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Old 10-26-2011, 07:34 AM   #36
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Having said all that, I found this helpful generalized site: “Insulating Your Hot Water Pipes…”.
Thanks MaintMan

I had seen that site before, it's a nice write up. It's what got me hunting around for thicker insulation types.

I have a few priorities as to insulating pipes:

1) Protect pipes in attic unconditioned space from freezing when not in use
2) Stop wasting heat (money) in places it doesn't belong
3) Keep heat in the pipes for faster DHW and heat at the convectors

For #1 I insulated the pipes in my attic space with those 2' fiberglass pipe insulators and wrap around foil-covered fiberglass for the areas that weren't straight pipes. I also draped and tucked the R13 FG batts being installed in my knee wall--the idea there to put the pipes inside the thermal envelope (even tho really, because FG is so air permeable, it won't work out very well). Ultimately I'd like to box in the pipes using 2x3's, plywood and FG, but that will have to wait until I have more time (Thanksgiving week).

For #2 & #3 I insulated my DHW pipes in the basement w/ the cheap R-2.2 foam and my heating pipes (also in basement) with a combination of both the 2' FG and the R-2.2 foam.

I haven't really noticed any difference in the speed that my DHW arrives at the bathroom taps. I also think that this effort to insulate heating pipes is going to literally be a drop in the savings bucket compared to the air sealing and other insulation work I'm doing.

The big push for me was really #1 ... last year when the house was vacant over the winter we left both heating zones set at 58*F. This year our usage model is very different, since we're living here we want the second floor to be warmer, but we don't necessarily want to run the central heat to produce the temperatures we want, so we're supplementing with a small electric radiator to keep the room up to the 68-70* we want. However, since the radiator and the central heat thermostat for 2nd floor are in the same room that means the 2nd floor central heat will probably not be kicking on much (if at all), that's why I'm now concerned about freezing pipes. I think a potential fix for this is to relocate the thermostat outside of our bedroom, that way the 2nd floor central heat can be set at ~62*F (or something low) and kick on/off as needed (keeping pipes warm), I just haven't done that yet.
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Old 10-29-2011, 08:31 PM   #37
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Hi all. First time poster here. I found this thread while doing a Google search on the foam pipe insulation. I bought a house two years ago that was built in 2003. I'm in South Carolina and never thought I'd have frozen water pipes, but I've had that the last two winters. All of my water lines are PEX, and they run through the attic. The insulation in the attic is blown in fiberglass. None of the water pipes are insulated, and the contractor did a bad job with the blown in insulation. So my plan is to insulate all the water piping running through the attic, both hot and cold. I'm going to use the Armacell self-sealing foam insulation from Home Depot. I thought everything was going to be plain and simple, but then in this thread I'm reading about condensation on the cold water lines. Should I reconsider insulation the cold water lines? I planned on doing this next week but will now hold off until someone can give me a definitive answer about the cold water condensation. Thanks for any help!
While I'm insulating the pipes, I have to replace all the rafter vents and clean out the soffit vents. Gotta love contractors who could care less about quality....
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Old 03-21-2016, 03:34 PM   #38
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Re: Pipe insulation: Foam, Rubber, Other?


Hi everyone. I've read this entire thread as I'm in a similar situation as the OP. The twist is that my house was remodeled and the existing cast iron piping was re-piped with copper. With the house being built in the 50's, the cold and hot water pipe are run overhead in the attic. The plumber didn't bother insulating it or even recommending that we insulate our water pipe. So now when the temperature outdoors reaches 85 degrees +, and you turn on the cold water, a burst of scalding hot water will first be dispersed. This didn't make sense at first but after examining pipes and the lack of insulation, it makes perfect sense. As temperatures in the attic reach well over 125+ degrees on a hot day, it heats up the water that is in the copper pipes in the attic.

I've read in this thread that some people recommend not insulating the cold water pipe unless freezing is a problem. In this case, I would have to insulate the cold water pipe with the self sealing PE pipe insulation. With it being 100% closed cell, would I need to worry about any possible condensation? Would anyone recommend also insulating the hot water pipe with the self sealing PE pipe insulation to help with heat loss in the early hours of the morning after a cold night? And any recommendations for taping the joints as well?

Last part. Even if I manage to insulate most of the pipe in the attic (some will be darn near impossible given the pitch of my roof and where the pipe runs to exterior wall cavities... There is still a chance that the copper lines that are in exterior wall cavities will heat up on a hot day right? So is there another alternative to insulating the pipe overhead?

Thank you for the help in advance.
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Old 03-21-2016, 03:56 PM   #39
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Re: Pipe insulation: Foam, Rubber, Other?


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I would have to insulate the cold water pipe with the self sealing PE pipe insulation. With it being 100% closed cell, would I need to worry about any possible condensation?
I think condensation will be more of an issue in a hot/humid attic with the pipe exposed to all of the air mass. I think you'll have less condensation if you have a tight fitting foam rubber insulation against the pipes because there will be less humid air circulating around it--No humid air, no condensation.

Insulating the hot water would make sense if the attic ever gets cold, such as overnight when you want early morning showers.

For my exposed attic heating pipes I used Aramcell foam insulation, it had tape on either side of the split so that it would seal together. I then over-wrapped on the straight sections with paper-backed fiberglass pipe insulation (which had an integrated adhesive tape flap for sealing. For bends I used a paper backed fiberglass wrap and some foil tape.

I wrapped a thermocouple against the pipes to monitor the temperature and found that even when the outside air was in single digits, and the attic air was in the 20s (F), the pipes would never drop below much below high 50s (F) even if the heat zone had been inactive for several hours--as in, the heat from the interior space of the house would heat the pipes before/after the attic entry and that would bleed back keeping them at reasonable temperatures. For my purposes that was a success because my concern was frozen heating pipes in the winter.

Even if you can't insulate every inch of your copper pipes I would guess that insulating as much as you can would be a help in preventing transfer of the ~125F attic temps to your copper pipes, and will reduce the amount of condensation dripping down on to your existing insulation.

Creative use of spray foam insulation can also help to insulate from the higher attic temps in the tighter areas.

As an alternative--if the pipes are tight to, or at least close to, the joists you could also build boxes out of 1" rigid insulation and try to move the pipes into the conditioned space of your house vs. the unconditioned attic.
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Old 03-21-2016, 04:10 PM   #40
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Re: Pipe insulation: Foam, Rubber, Other?


Thank you bubbler! Very useful information. I will measure out the pipe sizes and count the number of T's and elbows I will need to start insulating this weekend.
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Old 03-21-2016, 06:57 PM   #41
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Re: Pipe insulation: Foam, Rubber, Other?


Keep us posted how it works out, but I am concerned that 1" of insulation around the pipes is just going to have it take 4 hours to get the water in the pipe to 125 rather than 2 hours. Just guessing on the numbers, but you get my point. Bublers last paragraph of making the pipe area part of the conditioned space has a lot of merit, but may be more difficult.

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