Code Cycle: 2016 & 2019 Standards
Reference: CalCERTS New Construction Training Manual Chapter 5, Section 5
HERS Verified Central Parallel Piping (PP-H)
The primary design concept in a central parallel piping system is an insulated main trunk line that runs from the water heater to one or more manifolds, which then feeds use points with ½” or smaller plastic piping. (Figure 5-9) shows a traditional central system with a single manifold. With the advent of mini-manifolds, the central parallel piping system can now accommodate multiple mini-manifolds in lieu of the single central manifold.
Installation Criteria and Guidelines
The intent of a good parallel piping design is to minimize the volume of water entrained in piping between the water heater and the end use points. The focus is on reducing the length of larger diameter lines from the water heater to the manifolds.
A compliance credit is available for installations that have less than 5 feet of piping between the water heater and manifolds when verified by a HERS Rater. The Parallel Piping verification protocol RA3.6.4 also requires HERS verification of Pipe Insulation per RA3.6.2 , See article titled "2016 & 2019 HERS Residential Hot Water Distribution Pipe Insulation Requirements."
HERS Verification: RA3.6.4
This measure expands on the requirements for parallel piping systems that use one or more central manifolds with individual runs from the manifold to each point of use. Visual inspection shall verify that all supply lines of the parallel piping system meet the specific installation requirements listed below:
- The measured length of pipe from the water heater to each central manifold shall not exceed 5 feet (measured to the nearest half foot).
- The hot water distribution system piping from the manifold to the fixtures and appliances must take the most direct path. For example, in a house with more than 1-story and the water heater in the garage, this requirement would exclude running hot water supply piping from the manifold to the attic, and then running the line back down to a first floor point of
- The hot water distribution piping must be separated by at least two inches from any other hot water supply piping, and at least six inches from any cold-water supply piping
- The HERS inspector shall also verify that other hot water piping is insulated and installed to meet the requirements of RA3.6.2.