Install Instructions

Viega PureFlow System Design Considerations
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IM-PF 724596 1021 PureFlow Water System (EN)
6.4.2.2 Plumbing Code Compliance (Home Run / Parallel Systems)
The Viega ManaBloc system is listed to ASTM F876/F877 standards for
cross-linked polyethylene (PEX) distribution systems. The below model
plumbing codes recognize and allow the use of PEX distribution systems:
■ International Plumbing Code (IPC)
■ Uniform Plumbing Code (UPC)
■ National Plumbing Code (NPC)
Sizing of Parallel Water Distribution Systems (ManaBloc) is addressed
in these model plumbing codes under their respective water supply and
distribution sections. The Viega ManaBloc is also IAPMO (UPC) and ICC-ES
PMG listed for use with ⅜" and ½" PEX tubing sizes for water distribution.
6.4.3 Combination Systems
PEX combination systems can be sized in a similar manner as a typical
branch-and-tee system. Refer to your local or model plumbing code
for the required tube and manifold sizing based on the system demand
(Water Service Fixture Units, WSFU). If low service pressure is present,
Viega provides the equivalent feet of PEX tubing factors for PEX 󶈵ttings to
ensure any additional pressure drop is accounted for in your design.
6.4.3.1 Design Factors for Combination Systems
Design the Layout as Condensed as Possible
Keep the main hot supply line close to the 󶈵xture groups with the branch
lines shorter than six feet. This will help provide hot water in a reasonable
amount of time with less wasted water.
The limiting factor for installers to accomplish an optimal design is how
spread out the 󶈵xture groups are within the structure.
If there is a 󶈶oor plan that incorporates stacked or back-to-back 󶈵xture groups,
a combination system can be an e󶈴ective alternative to a parallel system.
6.4.4 Branch-and-Tee Systems
The same general sizing practices can be applied to a PEX branch-and-
tee system as with any code-approved piping material. Refer to your local
or model plumbing code for proper tube sizing.
6.4.4.1 Design Factors for Branch-and-Tee Systems
Just like the combination system, condensed 󶈶oor plan layouts are preferable
to minimize the length and the amount of water stored in the main supply line,
minimizing the amount of water purged before hot water reaches the 󶈵xtures.
These systems can also su󶈴er from 󶈶uctuating pressure during multiple 󶈵xture use.
If the 󶈵xture groups are not condensed, a branch-and-main system will
have slow hot water delivery times and substantial water waste.