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Mounting Surface for Pumps

Scope

Include adequate, sturdy wall space within a utility room when building a Renewable Energy Ready Home (RERH). Attach a piece of plywood to the wall for mounting solar water heating equipment including the pump and gauges. 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

  • Dedicate and label a 3 ft x 2 ft plywood panel area adjacent to empty space (for the solar hot water tank) for the balance of system components/pumping package.

Alternative: Blocking is permitted to be used as an alternative to the 3’ x 2’ wood panel area designated for the future panel to mount solar HW components shall be clearly noted in the system documentation.

Note: Homes equipped with an ENERGY STAR qualified whole-home gas tankless water heater or an ENERGY STAR qualified heat pump water heater are exempt from this provision. (See the Compliance Tab for additional details and exceptions.)

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.

When constructing a home to be renewable energy ready, space should be allocated in the utility room for solar water heating components, including a solar hot water tank and associated components. To meet the requirements of the DOE Zero Energy Ready Home program, dedicate space on the utility room wall for mounting the balance of system components.  A plywood panel at least 3 ft x 2 ft should be fastened to the wall and clearly labeled as the “Balance of System Board.” This panel should be labeled on the plumbing riser diagram as an RERH component.

The purpose of the plywood backing is to

  • Ensure a dedicated space for these components.
  • Provide a secure foundation for mounting future equipment.
  • Facilitate the future installation of these components by the installer.

How to Designate Utility Room Space for the Balance of System Board

  1. To meet the requirements of the DOE Zero Energy Ready Home program, designate a dedicated space for the future balance of system components, 3 ft tall by 2 ft wide. Locate the wall space adjacent to the empty space dedicated to the home’s future solar hot water heater.
  2. Label the space by placing a water resistant 10 in. x 6 in. label or sign in the center of the plywood that reads “Renewable Energy Ready Home - Solar Thermal Balance of System Board.”
  3. Record the balance of system wall location on the utility room floor plan to be provided to the homeowner. See Figure 1.
  4. Record the balance of system wall location on a plumbing riser diagram.
Utility room floor plan
Figure 1. The utility room floor plan should include the location of the existing hot water heater, designated space for a future hot water storage tank, electrical outlet, and balance of system plywood panel.

The Balance-of-System (BOS) components include all of the electrical, mechanical and hardware elements integrated into the solar hot water system.  Some of those elements include: pumps, valves, and the differential controller.  Many of the BOS components need to be protected from the weather elements.  The parts that are required to be installed in weather-resistant enclosure require proper working and maintenance clearances.  As this guide describes, a secure mounting space is required for those components as well.

Pump

In many types of solar hot water installations, a pump is required to circulate water from the storage tank to the solar array on the roof.

Gauges and Valves

Pressure gauges and relief valves help maintain the proper water pressure in the system.  If the water pressure ever exceeds a certain limit, the relief valve allows pressure to escape the closed loop, ensuring system pipes remain intact.

Differential Controller

This control mechanism compares the temperature between the storage tank and the solar collector.  If the solar collector is hotter than the storage tank by a certain amount, the controller turns on the circulation pump. 

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 guarantee 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.

Average daily solar radiation per month
Map of average daily solar radiation per month

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 and label a 3’ x 2’ plywood panel area adjacent to the solar hot water tank for the balance of system components/pumping package."

Alternative: Blocking is permitted to be used as an alternative to the 3’ x 2’ wood panel area designated for the future panel to mount solar HW components shall be clearly noted in the system documentation.

Homes equipped with an ENERGY STAR qualified whole home gas tankless water heater or an ENERGY STAR qualified heat pump water heater are exempt from these provisions.

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.
Requirements of free south roof area for various house size and method
Requirements of free south roof area for various house size and method

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 R401.3 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 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: 07/21/2014