This thread seems to be the definitive source on pipe insulation! While that's great, it underscores how underdeveloped this market segment is with regards to information. I agree with another, the information is very contradicting. In the interest of providing a better understanding of PE and EPDM rubber pipe insulation, I compared PE and EPDM rubber products from Nomaco, TundraFoam, and Frost King. Nomaco is the highest rated cross-linked PE I found at 210 F and is the only GreenGuard certified product. Of the TundraFoam and Frost King products, I preferred the TundraFoam products. Their EPDM rubber is higher temperate rated and the quality seems better. For example, both their PE and EPDM Rubber come with a tape flap that seals the seam as well as the adhesive in the seam itself. Whether or not this provides a more airtight seal remains to be seen but my guess is it would help eliminate installation errors and holdup better over time. Without a tape flap, I'd consider taping. The Nomaco website provides the most info on their products. They don't sell rubber insulation. The others sell both.
I’m concerned about the following: condensation control, longevity, indoor air quality, heat insulation, and toxicity in a fire in this order. For me, cost is not a factor. Temperature rating is also a consideration but only because I believe a higher rated product likely will last longer and maintain its performance characteristics better. To compare, I looked at information in various forums and contacted the manufactures. None of the manufacturer reps however were engineers; largely sales persons. The wording used and the way in which they responded didn't leave me with much confidence with one exception. That exception however answered largely opposite everyone else. So again who do you believe? Here’s my data:
1.) Condensation Control
+ Rubber will create hydrochloric acid. None of the manufacturer reps knew anything about this and I couldn't find any other information. It'd be great if someone could chime in to confirm or deny this
+ One manufacturer claimed PE was better at moisture control, the others said Rubber is and absorbs less moisture. Is there a difference between cross-linked PE and regular PE?
+ Seems this thread overall believes PE is better for cold pipes; both companies offering EPDM rubber said their rubber product is
My take: datasheets from the manufactures indicate both pass at least some moisture; neither a lot. Each measured this differently so I'm not sure which is better. Sounds like both work unless you believe the hydrochloric acid statement. I'll call this a tie and look at the other factors to decide
2.) Longevity
+ Definitely a disagreement here. Some say PE lasts forever yet the manufactures not only warranty PE for a shorter period but their reps also say rubber lasts longer
+ The reps did not know anything about rubber losing insulation value over time
+ Others say rubber hardens over time
My take: I'm confused why the manufactures don't warranty PE for as long as rubber. I'm guessing this is because rubber deteriorates less when exposed. If exposing to elements such as outdoor use or UV, rubber seems like the way to go. If well protected, both seem to last a long time (30+ years). My feeling is PE will last longer based on possible decline in insulation peformance reported (if true). It makes sense to me that rubber may harden over time. Will non-cross linked PE last longer than rubber on heated pipes given its lower temperature rating though? For cold water pipes, PE but again I feel the data is lacking.
3.) Indoor Air Quality
+ IAQ appears to have been ignored by the industry with the exception of Nomaco.
+ Two of the reps claim their products produce no VOCs
+ These same manufactures did not provide MSDN sheets. When asked, I did get one for their PE product (why no rubber?!). However, the MSDN provided looked minimally filled out so I question how much was really tested.
+ Another industry rep said all products off-gas but as long as they are cured right, it’s not a problem for either PE or Rubber.
My take: both PE and Rubber off-gas a least a little. I can’t imagine any rubber based product not producing anything. I expect rubber to produce more VOCs than PE. To hear two of the reps say their products produce no VOCs whatsoever seems extremley doubtful. Perhaps the level is so low it isn’t a concern but I want to know the specifics. Big kudos to Nomaco for leading the industry here. Since the others provided no information, I can only go with my instinct and say PE will be better. While I don't know, perhaps the Nomaco product is better as well since they at least paid attention.
4.) Heat insulation
+ PE and Rubber have the same insulation properties; at least to start
+ Some say Rubber degrades over time but PE does not
+ One rep had no idea. Another calmed they had never heard of rubber losing insulation ability over time. The last rep confirmed PE doesn’t lose its insulation ability over time
+ Someone on this thread said rubber can shrink up to 25% and PE only 3%. One product rep responded saying the opposite: rubber approximately 1% and PE 3% and only at the upper temperature ratings.
My take: hard to know what to believe. A higher rated product will likely do better IMO and won't hurt. That said both PE and rubber should be fine considering the rating of even the lower PE variety is 160 degrees F which is still hotter than your typical hot water at 120 F.
I thought it would be interesting to test so I bought a “stick” of each and took a blow torch to them. I know this isn’t a real exact test but it did provide some data to extrapolate from. Both contain a flame retardant and while both ignited, the flame instantly went out the moment the flame was removed. The PE pretty much melt away while the rubber maintained quite a bit more of its integrity. I didn’t have PEX to try but I am curious how it would do. In any case, I think you can conclude you won’t burn your house down if you run PE right up to your hot water heater though it is true it doesn’t hold up nearly as well to heat as rubber; at least at excessively high temps.
5.) Toxicity during a fire
+ The MSDN sheet for the PEX suggests Nomaco’s product produces very low toxic gas when burned
+ Some claim rubber pipe insulation emits a nasty toxic gas when it burns.
+ Both of the reps I talked with had no knowledge of rubber producing toxic gas when burned. They further didn’t know what I was talking about when I asked if their product was Halogen free. However, they did say their products are completely safe and do not produce any harmful products when burned.
My take: I doubt any of the products are better than the PEX; maybe the same. The fact two of the industry reps had no knowledge about claims of rubber emitting toxic gas when burned and didn’t know what I was referring to when asked if their product contained Halogen didn’t leave me with much confidence. To say they produce no harmful fumes when burned seems incredulous. With little additional information, I simply have no idea other than what has already been posted in this thread but my torch experiment did provide some clues. Both produced a white smoke. Both smelled. Doing this outside, I couldn’t tell much of a difference in the amount of smoke produced. I’d lean towards the rubber being worse if I had to choose but it didn't appear to be ghastly different.
My final conclusions? The information is very contradicting so I’m not 100% sure which is absolute "best". It doesn’t sound like you’d go horribly wrong using either.
I’ll likely use the Nomaco PEX for cold pipes and either the same or the TundraFoam Rubber for hot pipes; leaning again toward the Nomaco
Thanks for bringing it up. I definitely didn’t want to confuse anyone!
