EcoRenovator - View Single Post - What kind of PEX tubing for hydronic heat?

Mikesolar · 10-01-13, 07:19 AM

I have a Ph meter and regularly test glycol in solar systems and heat pump ground loops so, yes, it is essential to do so at some intervals. Solar systems should be done annually but ground source run at lower temps so I have seen glycol last 10+ years.

Many years ago (20 or so IIRC) I got ahold of the test data for barrier and non barrier tubing, both Wirsbo, REHAU, and Stadler and a couple of others as almost all were European made at the time and noted which ones had the lowest rates of diffusion. There is a few reasons why non barrier systems are not done in Europe and one of them is about liability. The contractor is responsible for the system for many years after installation and there is a great reluctance to have to go back and remedy something done 10 years previous.

I was once a witness for a big boiler company in court, when a homeowner sued said company because the cast boiler rotted out in 3-4 years. The HO was instructed to put in barrier tubing but to save money, put in non barrier. We were able to show that the O2 migration caused the failure and that it was not the responsibility of the boiler company. The tubing was tight, without leaks over the period so a massive amount of sediment was not the issue.

Some people do say that will all non ferric components, this shouldn't matter but to me a pump (for example) should last 40 years. In closed systems they do and in open systems, they usually don't. To me an closed, non barrier system is half way between an open system and a closed system with barrier tube. The standards describe the amount of diffusion over a period of time but we have to remember that the tubing is to be there for 50+ years.

Jeff has some good points, but my point is that we should design the system, not to be "good enough" but to last a long long time and good engineering means mitigation the effects of known issues. Barrier tubing is a no brainer.

As a side note, I think some companies will have more tube sales if they sell a slightly cheaper product so that might sway their opinions.

10-01-13, 07:19 AM	#10
Mikesolar Master EcoRenovator Join Date: Aug 2012 Location: Toronto Posts: 958 Thanks: 40 Thanked 158 Times in 150 Posts	I have a Ph meter and regularly test glycol in solar systems and heat pump ground loops so, yes, it is essential to do so at some intervals. Solar systems should be done annually but ground source run at lower temps so I have seen glycol last 10+ years. Many years ago (20 or so IIRC) I got ahold of the test data for barrier and non barrier tubing, both Wirsbo, REHAU, and Stadler and a couple of others as almost all were European made at the time and noted which ones had the lowest rates of diffusion. There is a few reasons why non barrier systems are not done in Europe and one of them is about liability. The contractor is responsible for the system for many years after installation and there is a great reluctance to have to go back and remedy something done 10 years previous. I was once a witness for a big boiler company in court, when a homeowner sued said company because the cast boiler rotted out in 3-4 years. The HO was instructed to put in barrier tubing but to save money, put in non barrier. We were able to show that the O2 migration caused the failure and that it was not the responsibility of the boiler company. The tubing was tight, without leaks over the period so a massive amount of sediment was not the issue. Some people do say that will all non ferric components, this shouldn't matter but to me a pump (for example) should last 40 years. In closed systems they do and in open systems, they usually don't. To me an closed, non barrier system is half way between an open system and a closed system with barrier tube. The standards describe the amount of diffusion over a period of time but we have to remember that the tubing is to be there for 50+ years. Jeff has some good points, but my point is that we should design the system, not to be "good enough" but to last a long long time and good engineering means mitigation the effects of known issues. Barrier tubing is a no brainer. As a side note, I think some companies will have more tube sales if they sell a slightly cheaper product so that might sway their opinions.