## 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.

(a) 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.

(b) Pipe insulation on the first five feet of hot and cold water piping from storage water heaters§150.0(j)

(c) 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).

(d) All underground hot water piping, all piping from the water heater to kitchen sinks and dishwashers and all non-recirculating hot water piping of 3/4" diameter or greater are mandatory measure as specified in §150.0(j)

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. Piping below grade that serves any island sinks or other island fixtures or appliances may be insulated with 1/2 inch wall thickness insulation.

### 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. Hot water piping from the water heater(s) to all fixtures and appliances shall be insulated based on the conductivity range in TABLE 120.3-A and the insulation level shall be selected from the fluid temperature range based on the thickness requirements in TABLE 120.3-A.

2. 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 and RA4.4.3 Pipe Insulation Credit (PIC)

### 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 or the hot water supply piping must be insulated based on the conductivity range in TABLE 120.3-A and the insulation level shall be selected from the fluid temperature range based on the thickness requirements in TABLE 120.3-A.

(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 (CHWDS-H)

To meet the Compact HWDS requirement, HERS field measurements shall verify that the longest measured pipe run length between a hot water use point and the water heater serving that use be no more than the distance specified in Table 3.6.4. Table 3.6.4 specifies the maximum pipe length as a function of Floor Area Served, where Floor Area Served is defined as the conditioned floor area divided by the number of installed water heaters.

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#### TABLE 3.6.5

Floor Area Served (ft2) | Maximum Measured Water Heater To Use Point Distance (ft)
< 1000 | 28’
1001 – 1600 | 43’
1601 – 2200 | 53’
2201 – 2800 | 62’
>2800 | 68’

Verification shall include:

(a) Verify that floor area (ft2) of the building matches the conditioned floor area that was used in compliance documentation. (Note: Floor Areas Served equals the conditioned floor area divided by the number of installed water heaters).

(b) Measure length from water heater to the use point furthest from the water heater and determine if that value is equal to or less than 'listed in Table 3.6.4. Measurements shall be made to the nearest half foot.

(c) 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 manifold to the attic, and then running the line back down to a first floor point of use.

(d) The HERS inspector shall also verify that hot water piping is insulated to a level that meets the requirements of §150.0(j) and is installed in accordance with Proper Installation of Pipe Insulation as specified in RA3.6.2.

### 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 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:

(a) 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.