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

Mikesolar · 09-29-13, 08:27 PM

Just to clarify some of AC comments, any of the the so called "1/2 inch" PEX tubes can use each others fittings as they all meet the CSA/UL standard. REHAU (my favorite) and Wirsbo (Uponor) are made the same way and have the same sizes (SDR9). Crimp fittings work on both as do as will compression fittings.

A word about O2 barriers. They are not all created equal. The REHAU barrier allows less O2 through the wall than the Uponor. Uponor used to have a tube called PE-PEX with 3 layers of O2 barrier but to compete with REHAU and Heat-link (back in the day), they dropped the layers to 2 (HE-PEX) which has slightly less protection.

No tube is impervious to O2, not even the Pex-al-pex. When the tube is bent, the AL can separate on the bend. It is a small opening but O2 can enter.

I have 15 - 20 year old boiler systems with this tube and there is often sludge in the tubing. This is true of any PEX tube, and it is only a matter of time before some sludge or corrosion is evident. It may take years. In extreme cases, the sludge due to filling and draining and filling again can clog up a pump, bronze or iron body.

My advise is to always use an O2 barrier tubing for any closed loop system. Penny wise and pound foolish.

09-29-13, 08:27 PM	#3
Mikesolar Master EcoRenovator Join Date: Aug 2012 Location: Toronto Posts: 958 Thanks: 40 Thanked 158 Times in 150 Posts	Just to clarify some of AC comments, any of the the so called "1/2 inch" PEX tubes can use each others fittings as they all meet the CSA/UL standard. REHAU (my favorite) and Wirsbo (Uponor) are made the same way and have the same sizes (SDR9). Crimp fittings work on both as do as will compression fittings. A word about O2 barriers. They are not all created equal. The REHAU barrier allows less O2 through the wall than the Uponor. Uponor used to have a tube called PE-PEX with 3 layers of O2 barrier but to compete with REHAU and Heat-link (back in the day), they dropped the layers to 2 (HE-PEX) which has slightly less protection. No tube is impervious to O2, not even the Pex-al-pex. When the tube is bent, the AL can separate on the bend. It is a small opening but O2 can enter. I have 15 - 20 year old boiler systems with this tube and there is often sludge in the tubing. This is true of any PEX tube, and it is only a matter of time before some sludge or corrosion is evident. It may take years. In extreme cases, the sludge due to filling and draining and filling again can clog up a pump, bronze or iron body. My advise is to always use an O2 barrier tubing for any closed loop system. Penny wise and pound foolish.