## RA3.6 Field Verification of Water Heating Systems

### RA3.6.1 Purpose and Scope

Water Heating HERS field verification offers credits for improved performance in terms of “quality” pipe insulation installation, for the installation of field-verified hot water distribution systems that are more compact and therefore perform better than typical hot water distribution systems and for the installation of specific circulation strategies. The 'listed HERS measures can be completed on a sampling basis.

### RA3.6.2 HERS-Verified Pipe Insulation Requirements for all Hot Water Distribution Systems

Unless otherwise stated, insulation must meet the requirements specified in §150.0(j). Pipe insulation shall fit tightly to the pipe and all elbows and tees shall be fully insulated. No piping should be visible due to insulation voids with the exception of the last segment of piping that penetrates walls and delivers hot water to the sink, appliance, etc. All domestic hot water piping shall be insulated as specified in Section 609.11 of the California Plumbing Code. In addition, the following piping conditions shall have a minimum insulation wall thickness of 1 inch:

(a) The first five feet of cold water piping from storage gas water heaters.

(b) All hot water piping with a nominal diameter between 3/4 inch (19 millimeter) and 1 inch.

(c) All hot water piping less than 3/4 inch in diameter that is associated with a domestic hot water recirculation system or leading to the kitchen fixtures.

1. (d) All underground hot water piping.

1. In addition, all piping below grade must be installed in a waterproof and non-crushable casing or sleeve that allows for installation, removal and replacement of the enclosed pipe and insulation. The internal cross-section or diameter of the casing or sleeve shall be large enough to allow for insulation of the hot water piping.

(f) Piping from the heating source to storage tank or between tanks

Pipe insulation may be omitted where hot water distribution piping is buried within attic, crawlspace or wall insulation, as described below: In attics and crawlspaces the insulation shall completely surround the pipe with at least 1 inch of insulation and the pipe shall be completely covered with at least 4 inches of insulation further away from the conditioned space. In walls, the insulation must completely surround the pipe with at least 1 inch of insulation. If burial within the insulation does not meet these specifications, then this exception does not apply, and the section of pipe not meeting the specifications must be insulated as specified in §150.0(j).

### RA3.6.3 HERS-Verified Pipe Insulation Credit (PIC-H)

The visual inspection shall verify that all hot water piping is insulated. This credit can only be taken for trunk and branch hot water distribution systems. Specific installation requirements include:

1. The HERS rater shall verify that all hot water piping is insulated in accordance with the provisions in RA3.6.2 HERS-Verified Pipe Insulation Requirements for all Hot Water Distribution Systems.

### RA3.6.4 HERS-Verified Central Parallel Piping (PP-H)

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:

(a) The measured length of pipe from the water heater to each central manifold shall not exceed 5 feet (measured to the nearest half foot).

(b) 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 use.

1. 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.

(c) The HERS inspector shall also verify that other hot water piping is insulated and installed to meet the requirements of RA3.6.2.

### RA3.6.5 HERS-Verified Compact Hot Water Distribution System Expanded Credit (CHWDS-H-EX)

To meet the Compact Hot Water Distribution System Expanded Credit eligibility requirements, the requirements in RA4.4.6 must be met. In addition, the following HERS field verifications are required:

(a) No hot water piping larger than 1 inch diameter is allowed,

(b) Length of 1 inch diameter piping is limited to 8 ft or less,

(c) Two and three story buildings cannot have hot water distribution piping in the attic, unless the water heater is also located in the attic, and

(d) Eligible recirculating systems must be HERS-Verified Demand Recirculation: Manual Control conforming to RA4.4.17.

### RA3.6.6 HERS Verified Demand Recirculation; Manual Control (R-DRmc-H)

Demand controlled recirculation systems shall operate “on-demand”, meaning that pump operation shall be initiated shortly prior to the hot water draw. The recirculation pump can be located external to the water heater or be integral to the water heater. The controls shall operate on the principal of shutting off the pump with a sensed rise in pipe temperature (Delta-T). For this HERS verification process, a manual switch is required.

Verification shall include:

(a) More than one circulation loop may be installed. Each loop shall have its own pump and controls.

(b) Verify that the pump, demand controls and thermo-sensor are present. Manual switches shall be located in the kitchen, all bathrooms, and any hot water fixture location that is at least 20 feet (measured along the hot water piping) from the water heater.

(c) Manual controlled systems may be activated by wired or wireless button mechanisms. Verify that manual controls have standby power of 1 watt or less.

(d) Verify that pump and control placement for the demand recirculation meets one of the following criteria.

1. When a dedicated return line has been installed the pump, controls and thermo-sensor are installed at the end of the supply portion of the recirculation loop (typically under a sink); or

2. The pump and controls are installed on the return line near the water heater and the thermo-sensor is installed in an accessible location as close to the end of the supply portion of the recirculation loop as possible (typically under a sink), or

3. When the cold water line is used as the return, the pump, demand controls and thermosensor shall be installed in an accessible location at the end of supply portion of the hot water distribution line (typically under a sink).

(e) Verify that a check valve is installed in the recirculation loop to prevent unintentional circulation of the water (thermo-siphoning) and back flow when the system is not operating. This check valve may be included with the pump.

(f) The HERS inspector shall also verify that the supply portion of each circulation loop, the first five feet of branches off the loop and the dedicated return line are insulated based on the conductivity range in TABLE 120.3-A, the insulation level shall be selected from the fluid temperature range based on the thickness requirements in TABLE 120.3-A and the insulation shall be installed in accordance with RA3.6.2 Other hot water piping shall meet the requirements of 150.0(j) and be installed in accordance with RA3.6.2. Insulation is not required on the cold water line when it is used as the return.

(g) The hot water distribution system piping from the water heater(s) 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 water heater to the attic, and then running the line back down to a first floor point of use.

(h) Verify that manual controls initiate pump operation by pressing one of the manual controls and observing that the pump turns on and then shuts off in accordance with one of the two methods 'listed.

1. After the pump has been activated, the controls shall allow the pump to operate until the water temperature at the thermo-sensor rises not more than 10ºF ( 5.6 ºC ) above the initial temperature of the water in the pipe, or

2. The controls shall not allow the pump to operate when the temperature in the pipe exceeds 102ºF (38.9 ºC).

(i) Verify that the controls have a feature that limits pump operation to a maximum of 5 minutes following any activation. This is provided in the event that the normal means of shutting off the pump have failed.

(j) The manufacturer(s) of the recirculation pump and the controls shall provide installation and operation instructions that provide details of the operation of the pump and controls and such instructions shall be available at the jobsite for inspection.

### RA3.6.7 HERS-Verified Demand Recirculation: Sensor Control (RDRsc-H)

Demand controlled recirculation systems shall operate “on-demand”, meaning that pump operation shall be initiated shortly prior to the hot water draw. The recirculation pump can be located external to the water heater or be integral to the water heater. The controls shall operate on the principal of shutting off the pump with a sensed rise in pipe temperature (Delta-T). For this HERS verification process a sensor control is used to activate the pump rather than a manual control.

Verification shall include:

(a) More than one circulation loop may be installed. Each loop shall have its own pump and controls.

(b) Verify that the pump, demand controls and thermo-sensor are present. Sensor controls shall be located in the kitchen, bathrooms, and any hot water fixture location that is at least 20 feet (measured along the hot water piping) from the water heater.

(c) Sensor controlled systems may be activated by wired or wireless mechanisms, including motion sensors, door switches and flow switches.

(d) Verify that sensors controls have standby power of 1 watt or less.

(e) Verify that pump and control placement for the demand recirculation meets one of the following criteria.

1. When a dedicated return line has been installed the pump, controls and thermo-sensor are installed at the end of the supply portion of the recirculation loop (typically under a sink); or

2. The pump and controls is installed on the return line near the water heater and the thermo-sensor is installed in an accessible location as close to the end of the supply portion of the recirculation loop as possible (typically under a sink), or

3. When the cold water line is used as the return, the pump, demand controls and thermosensor shall be installed in an accessible location at the end of supply portion of the hot water distribution line (typically under a sink).

(f) Verify that a check valve is installed in the recirculation loop to prevent unintentional circulation of the water (thermo-siphoning) and back flow when the system is not operating. This check valve may be included with the pump.

(g) The hot water distribution system piping from the water heater(s) 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 water heater to the attic, and then running the line back down to a first floor point of use.

(h) The HERS inspector shall also verify that the supply portion of each circulation loop, the first five feet of branches off the loop and the dedicated return line are insulated based on the conductivity range in TABLE 120.3-A , the insulation level shall be selected from the fluid temperature range based on the thickness requirements in TABLE 120.3-A and the insulation shall be installed in accordance with RA3.6.2. Other hot water piping shall meet the requirements of 150.0(j) and be installed in accordance with RA3.6.2. Insulation is not required on the cold water line when it is used as the return.

(i) Verify that sensor controls initiate pump operation by activating one of the sensor controls and observing that the pump turns on and then shuts off in accordance with one of the two methods 'listed.

1. After the pump has been activated, the controls shall allow the pump to operate until the water temperature at the thermo-sensor rises not more than 10ºF ( 5.6 ºC ) above the initial temperature of the water in the pipe, or

2. The controls shall not allow the pump to operate when the temperature in the pipe exceeds 102ºF (38.9 ºC).

(j) Verify that the controls have a feature that limits pump operation to a maximum of 5 minutes following any activation. This is provided in the event that the normal means of shutting off the pump have failed.

(k) The manufacturer(s) of the recirculation pump and the controls shall provide installation and operation instructions that provide details of the operation of the pump and controls and such instructions shall be available at the jobsite for inspection.

### RA3.6.8 HERS-Multiple Recirculation Loop Design for DHW Systems Serving Multiple Dwelling Units

The visual inspection shall verify that a central DHW system serving a building with more than eight dwelling units has at least two recirculation loops, each serving roughly the same number of dwelling. Unique building sections may have additional recirculation loops. These recirculation loops may be connected to the same water heating equipment or be connected to independent water heating equipment. The HERS inspector shall verify that there are at least two recirculation loops each serving roughly the same number of dwelling units. Unique sections of the building may have separate loops. Ideally each loop will have its own pump and controls.

### RA3.6.9 HERS-Verified Drain Water Heat Recovery System (DWHR-H)

A HERS inspection is required to obtain this credit. All DWHR unit(s) shall be certified to the Energy Commission according to the following requirements:

Vertical DWHR unit(s) shall be compliant with CSA B55.2, and tested and labeled in accordance with CSA B55.1 or IAPMO IGC 346-2017. Sloped DWHR unit(s) shall be compliant with IAPMO PS 92, and tested and labeled with IAPMO IGC 346-2017.

The DWHR unit(s) shall have a minimum rated effectiveness of 42 percent.

The HERS inspector shall verify that:

(a) The make, model, and CSA B55.1 or IAPMO IGC 346-2017 rated effectiveness of the DWHR unit(s) shall match the compliance documents. The DWHR unit(s) shall also be verified as a model certified to the Energy Commission as qualified for credit as a DWHR unit(s).

(b) The installation configuration (e.g. equal flow, unequal flow to the water heater, or unequal flow to the showers) and the percent of served shower fixtures shall match the compliance documents.

(c) For water heating system serving a single dwelling, the DWHR system shall, at the minimum, recover heat from the master bathroom shower and must at least transfer that heat either back to all the respective showers or the water heater.

(d) For central water heating system serving multiple dwellings, the DWHR system shall, at the minimum, recover heat from half the showers located above the first floor and must at least transfer that heat either back to all the respective showers or the water heater.

(e) The DWHR unit(s) shall be installed within 1 degrees of the rated slope. Sloped DWHR shall have a minimum lengthwise slope of 1 degree. The lateral level tolerance shall be within plus or minus 1 degree.

(f) The installation shall comply with any applicable California Plumbing Code requirements.