I know a little about PEX tubing, but not everything and would appreciate clarification about the difference between the various types of PEX. I am sure everyone would like to know why are there so many? Do different applications require different types of tubing and if so which type for which App?

        I quess the main reason for this is I do not know what the difference between 
PEX- B and PEX-C, is one better than the other? or just a different method of manufacturing?  Do some have better thermal properties than the others?  

Thanks Tom

Tom Pittsley
[email protected]
www.eebt.org

Here is a short description about A B and C link; http://www.blueridgecompany.com/documents/PEXa-b-c.pdf
We sell primarily Pex B made in China and Pex C made in the USA. Both meet the NSF quality standards and are held to regular NSF testing and regular random factory inspections.
Dan

PEX-A has memory, so it can be reformed if kinked with the application of heat. It is also typically less likely to kink in the first place. In many applications these are not big decisions, such as for slabs, but if working in tight quarters, PEX-A is typically superior for handling and kink repair.

For the vast majority of residential applications all "listed" PEX tubing is more than adequate being able to handle temperatures and pressures far beyond the loads presented. I have used all four common PEX tubes (and truck loads of polybutylene before that!) and have never had an issue. The fourth is a PEX-AL-PEX used for near piping on hot boilers.

I now prefer a pipe that is NSF/UL listed for plumbing AND heating as I get into both. More money, more flexibility, easier on the old back. But for the occasional user with low temp (radiant floor) applications, it is hard to argue for higher prices.

This link has info on the principal methods manufacturers are using today to make PEX from Dan Holohan's book: http://www.houseneeds.com/shop/heatingproducts/radiantheating/pex.asp

There's a lot of controversy on the types and performance ratings going on.

Here's a useful article on the types of PEX (a,b,c) and their advantages/disadvantages.

Most customers i design the projects for want a good price and good quality and when they ask me which type they need, i recommend probably 90% of the PEX-b and 10% PEX-Al-PEX.

Jessica

Why can't HDPE pipe be used - supposedly it is good up to 140F, which is above what some radiant systems should ever see.

Given the low pressures that could be used (with the right regulation), I've also wondered why there isn't a thinner walled pipe that conducts heat better.

Jonr,
You could use HDPE pipe and in fact we have used it on some comercial storage supply return lines when we needed 1 1/2 diamiter feeds.
but...... You will need a fusion tool ($2,500.00) or use barbed fittings with hose clamps,,,potential leaks.
This the industry standard is Pex A, B, C, AL and the fittings for manifolds and in wall runs are all redialy available and can be applied with a host of realitivly inexpensive tools.
Dan

Thanks, would have to add fusion tool rental/or service to the cost of HDPE.