Multi-story residential projects often use larger, commercial-grade products like iron pipe size (IPS) Schedule 80 CPVC piping for the building mains and risers and transition to residential, copper-tube-size (CTS) piping for distribution to fixtures. This practice is safe, effective and affordable when converting from CPVC to CPVC; however, when contractors transition to a material other than CPVC for the CTS distribution piping, it can put the integrity of the system at risk.
Corzan Schedule 80 CPVC is the material of choice for commercial buildings and large diameter residential mains and risers due to its high impact strength and inherent resistance to corrosion and scaling.
Copper-tube-sized FlowGuard Gold CPVC is the perfect material to pair with Corzan CPVC for partition piping and mains that are less than 2” in residential, multi-family and hotel projects. FlowGuard Gold CPVC is formulated and designed to be more ductile and flexible than Corzan at small diameters, making it ideal for residential ½” and ¾” piping applications.
Like Corzan, FlowGuard Gold CPVC is 100% immune to degradation and corrosion from chlorine-based disinfectants in potable water systems, and both can reduce the risk associated with biofilm formation, Legionella, and other bacterial growth. The one-step solvent weld process used by FlowGuard Gold CPVC simplifies installation and creates a strong CPVC-to-CPVC bond that is not subject to mechanical failures or other issues that can occur with multi-part mechanical fittings.
Both FlowGuard Gold and Corzan CPVC are U.S-made products that use compounds produced at the same plant in Louisville, KY to ensure consistent quality across the system. Both are also supported by the FBC System Compatible Program, which makes it easy to determine which ancillary products and chemicals are compatible and incompatible with the plumbing system.
When joined and tested properly, Corzan and FlowGuard Gold CPVC create a single-system approach to hybrid projects that has multiple advantages for contractors, building owners and occupants.
Contrast the single material integrity and benefits of a Corzan/FlowGuard Gold CPVC System with the challenges that are introduced with a mixed-material system.
When PEX is selected for distribution piping, the new material introduces water compatibility issues into the system that can impact reliability. PEX is known to be vulnerable to degradation and premature failure due to incompatibility with chlorine-based disinfectants in drinking water at temperatures above 140° F, pressures above 80 psi, and when the ORP of the water exceeds 825 mV. The first two of those will limit the peak performance for your entire system and the third creates a risk of premature failure that is completely outside your control.
Whenever PEX piping is used, you have to hope water conditions are in PEX’s “comfort zone” and the local utility doesn’t make any changes, like introducing chlorine dioxide disinfection, that can take the water out of that zone.
Another issue to consider when using PEX is the impact of PEX insert fittings on pressure and flow. Even expansion PEX fittings have a much smaller internal diameter than a CPVC fitting and that results in a larger pressure drop. According to a leading manufacturer of expansion PEX, the branch of a ½” expansion PEX tee has the equivalent length of 6.3 ft of pipe, which at 8 ft/sec. and 60° F is approximately 1.7 psi of pressure loss. For FlowGuard Gold CPVC, the equivalent length of that same branch is 3.11 ft., which at 8 ft/sec and 60° F is approximately 0.81 psi of pressure loss – a difference of 210%. If you’re using crimp style fittings, the difference can approach 500%.
Finally, there is the potential impact on water quality. CPVC has a lower biofilm formation potential than PEX so when you use PEX with CPVC risers you increase the risk of biofilm formation in the system, which can create a habitat for Legionella to multiply. You may also be reducing the building owner’s ability to mitigate potential water safety risks as the PEX piping can be damaged by flushing the system with water above 140° F or chlorine dioxide disinfection.
Connecting Corzan Schedule 80 CPVC to FlowGuard Gold CTS CPVC is easy, requiring just a simple bushing that is readily available in a full range of sizes. Depending on the connection, you’ll use either the two-step solvent weld process used with Corzan CPVC or the single-step process used with FlowGuard Gold CPVC. You can determine what process to use by the pipe color. Corzan pipe is gray and FlowGuard Gold pipe is tan. Whenever you are joining gray-to gray or tan-to-gray, use the two-step process. If you are joining tan-to-tan, single-step solvent cement can be used.
For step-by-step instructions for joining Corzan Schedule 80 CPVC and FlowGuard Gold CTS CPVC, see our joining instructions.