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Solar Plumbing and Wiring Chase

Scope

Install a plumbing and wiring chase from the utility room to the roof space designated for the future solar hot water array Space requirements and layout for solar water heating and photovoltaic system components should be taken into account early in the design process. 

DOE Zero Energy Ready Home Notes

The U.S. Department of Energy (DOE) Zero Energy Ready Home National Program Requirements includes in Exhibit 1, Mandatory Requirements, Item 7 Renewable Ready, that all homes must meet the requirements in the Consolidated Renewable Energy Ready Home (RERH) Checklist.

The RERH Checklist requires builders to

  • Install a single 4” chase or two 2” chases from utility room to the attic space below designated array location (cap and label both ends). (RERHSWH Guide 3.5)

See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Certified Homes, and Indoor airPLUS.

Description

A renewable energy-ready home (RERH) is one that is built with the wiring and plumbing conduit and other components in place to facilitate the future installation of solar photovoltaic panels and/or solar water heating panels. Some energy-efficiency programs, like the U.S. Department of Energy’s DOE Zero Energy Ready Home Program, require homes to be renewable-energy ready.

To meet the requirements of the DOE Zero Energy Ready Home program, install either a single 4” or two 2” PVC chases from the utility room to the roof space (see Figure 1). The pipe chase should be installed as a straight run and be clearly labeled as an RERH component.

A single straight 4” pipe chase or two 2” pipe chases installed in a straight run from the utility room to the underside, or attic side, of the designated solar array roof area will allow for the installation of the solar pipes and pipe insulation during the solar system installation. The pipe chase can be made of lightweight PVC or any other code-compliant material that is favored in the local housing market. It is not recommended to use a boxed-in open chase in the wall as other contractors may inadvertently install wires, plumbing, and ductwork through it. The use of a boxed-in open chase may also compromise the integrity of the home’s thermal shell. With this in mind, the chase should be capped on both ends and sealed at all floor and ceiling penetrations to maintain air tightness and mandatory fire ratings.

A straight pipe chase between the utility room and the attic is the recommended method. Minor horizontal pipe runs at either end of the pipe chase are allowable. However, in situations where the pipe chase between the attic space and the utility room travels at a slope, bends, or terminates in an area lacking sufficient access or in a way that would prevent the continuation of the pipe run to the collector area or solar storage tank, it is recommended that the actual system water pipes be installed between the utility room and the roof area. A certified NABCEP solar professional should be consulted when installing the actual pipe run as opposed to a pipe chase.

The termination of the pipe chase or pipes should extend above the attic insulation by 6 inches and be located in an area that provides sufficient accessibility and clearance: 18 inches from the top of the chase to the underside of the roof deck. This is so a solar installer can have room to continue the pipe run above the roof deck to the solar array, at a future point in time. If the actual pipes are run to the roof, they must terminate at a universally convenient location relative to the proposed solar array location. The end of the pipe chase or pipes should be labeled to indicate its purpose and intended use.

How to Install a Pipe Chase for Solar Hot Water

  1. Designate a proposed location and square footage for the solar hot water array on the roof (preferable directly above the utility room).
  2. Install a single 4” chase or two 2” chases from utility room to the attic space below designated array location.
  3. Ensure the chase terminates at least 6” above the attic floor insulation (if applicable) and at least 18” below the attic roof deck.  Cap both ends.
  4. Wrap a 3” x 1” label around the chase so the text is visible and upright (if possible).  The label should read, “Renewable Energy Ready Home – Solar Thermal Pipe Chase.” 
  5. Record the pipe chase location on a plumbing riser diagram.
    Plumbing riser detail
    Figure 1. An accurate plumbing riser detail helps contractors and homeowners understand how all the components of the Consolidated Renewable Energy Ready Home checklist fit together. 

Ensuring Success

Ensure adequate utility room early in the house design process to allow for ample space for solar water heating and photovoltaic system components. 

Confirm with local code officials early in the design process what steps are needed to ensure that installation of solar water heating panels will meet with local codes, homeowner's association covenants, and historic district regulations. See the article on building codes and regulations related to solar water heating systems at Energy.gov for additional information.

Protect the electrical and mechanical components of the solar water heating system from bulk moisture, high temperatures, and direct sunlight.  The utility room should be properly ventilated and maintain average indoor temperatures.

Climate

The DOE Zero Energy Ready Home program’s Consolidated Renewable Energy Ready Home (RERH) Checklist is required only under the following condition related to climate:

  • Location, based on zip code, has at least 5 kWh/m2/day average daily solar radiation based on annual solar insolation using the PV Watts online tool.

In climates where freezing temperatures are likely to occur, a closed-loop anti-freeze system with heat exchanger will keep outdoor water pipes from bursting.

Map of average daily solar radiation
Map of average daily solar radiation

Training

Right and Wrong Images

None Available

Presentations

  1. Zero Energy Ready Home Training
    Author(s): Rashkin
    Organization(s): DOE

Videos

None Available

CAD Images

None Available

Compliance

The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

DOE Zero Energy Ready Home (ZERH) Program

The DOE ZERH Consolidated Renewable Energy Ready Home (RERH) Checklist states:

“Install a single 4" chase or two 2" chases from utility room to the attic space below designated array location (cap and label both ends)"

Homes that already have a solar hot water system installed do not need to meet the SHW requirements of the Consolidated RERH checklist.

DOE Zero Energy Ready Home National Program Requirements Mandatory Requirement 7 (Renewable Ready) shall be met by any home certified under the DOE Zero Energy Ready Home program, only where all of the following conditions are met:

  1. Location, based on zip code has at least 5 kWh/m2/day average daily solar radiation based on annual solar insolation using PVWatts online tool, AND;
  2. Location does not have significant natural shading (e.g., trees, tall buildings on the south-facing roof, AND;
  3. Home as designed has adequate free roof area within +/-45° of true south as noted in the table below. Note that in some cases a house may have insufficient roof area for the Solar Electric RERH checklist, but it may still have the minimum roof area for the solar thermal RERH Checklist and would therefore have to comply with the Solar Thermal RERH checklist. In other cases, the home may only have adequate south facing roof for the Solar Electric or Solar Thermal RERH Checklist, but not both. In that case the builder can decide which one of those two checklists to apply.
ZERH table of requirements for south roof area
Table 1. ZERH Requirements for south roof area

ENERGY STAR Certified Homes

The ENERGY STAR Certified Homes National Program Requirements for Homes states that “Dwelling units in multifamily buildings with 4 or 5 stories above-grade are eligible to earn the ENERGY STAR if each unit has its own heating, cooling, and hot water systems4, separate from other units, unless the domestic hot water is provided by a solar system.  Then (Footnote 4), “Central systems for domestic hot water are allowed for domestic hot water if solar energy provides at least 50% of the domestic hot water needs for the residential units.”.

2009, 2012, 2015, and 2018 IECC

Section 401.3 A permanent certificate shall be posted on or near the electrical distribution panel that lists types and efficiencies of water heating, heating, and cooling equipment, as well as insulation R values, and window U and SHGC factors.

Retrofit: 2009, 2012, 2015, and 2018 IECC

Section R101.4.3 (Section R501.1.1 in 2015 and 2018 IECC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)

2009, 2012, 2015, and 2018 IRC

Follow the requirements for solar water heating systems found in the IRC Section M2301 Solar Energy Systems (Solar Thermal Energy Systems in 2015 and 2018 IRC).

Retrofit: 2009, 2012, 2015, and 2018 IRC

Section N1101.3 (Section N1107.1.1 in 2015 and 2018 IRC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)

Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.

2009, 2012, 2015, and 2018 International Mechanical Code (IMC)

Follow the requirements for solar water heating systems found in the IMC, Chapter 14, Solar Systems (Solar Thermal Systems in 2018 IMC).

More Info.

Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

Case Studies

  1. Author(s): PNNL, ORNL
    Organization(s): PNNL, ORNL
    Publication Date: December, 2010

    Case study about a 20-unit community of energy-efficient duplexes in Massachusetts that incorporated solar water heating and photovoltaics.

References and Resources*

  1. Author(s): Department of Energy
    Organization(s): DOE
    Publication Date: June, 2012

    Website with consumer and contractor information about building codes and regulations for solar water heating systems.

  2. Author(s): Department of Energy
    Organization(s): DOE
    Publication Date: April, 2017

    Standard requirements for DOE's Zero Energy Ready Home national program certification.

  3. Author(s): Aldrich
    Organization(s): CARB, Steven Winter Associates, SWA
    Publication Date: March, 2013

    Brochure on specifications for solar thermal systems.

  4. Author(s): U.S. Environmental Protection Agency
    Organization(s): EPA
    Publication Date: January, 2011

    The RERH specifications and checklists take a builder and a project design team through the steps of assessing a home’s solar resource potential and defining the minimum structural and system components needed to support a solar energy system.

  5. Author(s): FSEC
    Organization(s): FSEC
    Publication Date: July, 2014
    Website with information for consumers about solar thermal systems for homes.

Contributors to this Guide

The following authors and organizations contributed to the content in this Guide.

Last Updated: 07/22/2014