stream of the 24 inch cold water inlet pipe. An appropriately rated pressure and temperature relief valve shall be installed on all water heaters at the port specified by the manufacturer. Discharge piping for the relief valve shall be non-metallic. If heat traps

and/or piping insulation and/or pressure relief valve insulation are supplied with the water heater, then they shall be installed for testing. Clearance shall be provided such that none of the piping contacts other surfaces in the test room.

4.4. Fuel and/or Electrical Power and Energy Consumption. Install one or more instruments which measure, as appropriate, the quantity and rate of electrical energy and/or fossil fuel consumption in accordance with section 3.

4.5. Internal Storage Tank Temperature Measurements. Install six temperature measurement sensors inside the water heater tank with a vertical distance of at least four inches between successive sensors. A temperature sensor shall be positioned at the vertical midpoint of each of the six equal volume nodes with the tank. Nodes designate the equal volumes used to evenly partition the total volume of the tank. As much as is possible, the temperature sensor should be positioned away from any heating elements, anodic protective devices, tank walls, and flue pipe walls. If the tank cannot accommodate six temperature sensors and meet the installation requirements specified above, install the maximum number of sensors which comply with the installation requirements. The temperature sensors shall be installed either through; (1) The anodic device opening; (2) the relief valve opening; or (3) the hot water outlet. If installed through the relief valve opening or the hot water outlet, a tee fitting or outlet piping, as applicable, shall be installed as close as possible to its original location. If the hot water outlet includes a heat trap, the heat trap shall be installed on top of the tee fitting. Added fittings shall be covered with thermal insulation having an R value of 4 hr⚫ft2°F/Btu.

4.6. Ambient Temperature. The ambient air temperature shall be measured approximately at the vertical mid-point of the heater and approximately 2 feet from the surface of the water heater. The sensor shall be shielded against radiation.

4.7. Inlet and Outlet Water Temperature Measurements. Install temperature sensors in the cold-water inlet pipe and hot-water outlet pipe as shown in Figures 1, 2, or 3, as applicable.

4.8. Flow Control. A flow control valve shall be installed to provide flow as specified within section 5.

4.9. Flue Requirements.

4.9.1. Oil-Fired Water Heaters. Establish a draft at the flue collar as specified in the manufacturer's literature. Establish the draft by using a sufficient length of vent pipe connected to the water heater flue outlet and directed vertically upward. For an oilfired water heater having a horizontally discharging draft hood outlet, a 90 degree elbow having a diameter equal to the largest flue collar size of the draft hood shall be connected to the draft hood outlet. A length of vent pipe sufficient to establish the draft shall be connected to the elbow fitting and oriented to discharge vertically upward. Direct vent oil-fired water heaters should be installed with venting equipment as speci

fled in the manufacturer's instructions, using the minimum vertical and horizontal lengths of vent pipe recommended by the manufacturer.

4.9.2. Gas-Fired Water Heaters. Establish a natural draft in the following manner. For gas-fired water heaters having a vertically discharging draft hood outlet, a 5 foot vertical vent pipe extension having a diameter equal to the largest flue collar size of the draft hood shall be connected to the draft hood outlet. For gas-fired water heaters having a horizontally discharging draft hood outlet, a 90 degree elbow having a diameter equal to the largest flue collar size of the draft hood shall be connected to the draft hood outlet. A 5 foot length of vent pipe shall be connected to the elbow and oriented to discharge vertically upward.

Direct vent gas-fired water heaters shall be installed wth venting equipment specified in the manufacturer's instructions using the minimum vertical and horizontal lengths of vent pipe recommended by the manufacturer.

4.9.3. Heat Pump Water Heater Storage Tank. The tank to be used for testing a heat pump water heater without a tank supplied by the manufacturer shall be an electric storage type water heater having a volume of 47.0 gallons ± 1 gallon with an Energy Factor of 0.87.01 as determined in accordance with section 6.1.7 with two 4.5 kW heating elements controlled in such a manner as to prevent both elements from operating simultaneously.

5. Test Procedures

5.1. Storage Tank and Heat Pump Water Heaters.

5.1.1. Determination of Storage Tank Volume. Determine the storage capacity, V., of the water heater under test, in gallons, by subtracting the tare weight-measured while the tank is empty-from the gross weight of the storage tank completely filled with water with all air eliminated and line pressure applied as described in section 2.5. and dividing the resulting net weight by the density of water at the appropriate temperature.

5.1.2. Setting the Thermostat for a Thermostatically Operated Water Heater. Starting with a tank of supply water, initiate normal operation of the water heater. After cutout, observe the mean tank temperature (based on the six temperature sensors) every minute until the maximum value is observed. Determine whether this maximum value of the mean tank temperature is within the range of 135°F ±5°F. If not, turn off the water heater, adjust the thermostat, and refill the tank with supply water. Then, initiate normal operation of the water heater, and once again determine the maximum mean tank temperature after cut-out. Repeat this sequence until the maximum mean tank temperature after cut-out is within the

range of 135°F ±5°F. If a water heater has two thermostats, the thermostat which controls the upper heating element shall be set first to yield a maximum water temperature of 135°F 15°F as measured by the temperature tank sensors above the upper heating element. The thermostat which controls the lower heating element shall then be set to yield a maximum mean tank temperature of 135°F 15°F. For heat pump water heaters, which control an auxiliary resistance element, the thermostat shall be set in accordance with the manufacturer's installation instructions.

5.1.3. Power Input Determination. For all water heaters except electric types having immersed heating elements and initiate normal operation and determine the power input, P, to the main burners (including pilot light power, if any) after 15 minutes of operation. If the water heater is equipped with a gas appliance pressure regulator, the regulator outlet pressure shall be set within £10% of that recommended by the manufacturer. For oil fired water heaters the fuel pump pressure shall be within ±10% of the manufacturer's specified pump pressure. All burners shall be adjusted to achieve an hourly Btu rating that is within ±2% of the value specified by the manufacturer. For an oilfired water heater, adjust the burner to give a CO2 reading recommended by the manufacturer and an hourly Btu rating that is within 12% of that specified by the manufacturer. Smoke in the flue may not exceed No. 1 smoke as measured by the procedure in ASTM-D-2156-80. Gas- and oil-fired water instantaneous water heaters shall have the burners adjusted to the manufacture's maximum firing rate value.

5.1.4. First Hour Rating Test. Establish normal water heater operation with the maximum mean tank temperature within the range specified in section 2.1.4. Begin the first hour rating test after the thermostat has acted to reduce the electrical power or fuel input to the water heater and the maximum storage tank temperature has been achieved. If the water heater incorporates a heat-pump, wait until both the heat pump and electrical heating element(s) have ceased to supply energy to the storage tank. Record the time, oil, gas and/or electrical meter readings as appropriate. Do not interrupt electrical power and/or fuel to the water heater. The rate of water withdrawal shall be 3.00+0.25 gallons per minute. Draw and collect water withdrawn from the water heater in a suitable container for the purpose of determining its weight at the conclusion of the test. During the draw record the inlet and outlet fluid temperature beginning 15 seconds after the start and at every subsequent 5 second interval throughout the duration of each draw. Alternatively, a water meter may be used to directly measure the volume of water withdrawn. Record the maximum out

let temperature which occurs during the draw as Tmax. The withdrawal of water shall continue until the outlet temperature drops to a value 25°F below Tmax, defined as Tmin, at which time the draw shall be terminated. Record the average outlet temperature and mass removed as Teli and M1, respectively. If the thermostat acts to reduce the supply of fuel to the main burner or electrical input to the upper heating element of a multiple element electric water heater, or electrical input to a water heater having a single element or multiple elements which operate simultaneously, before one hour has elapsed, initiate a second draw. During the draw record the outlet fluid temperatures beginning 15 seconds after initiating the draw and at every subsequent 5 second interval throughout the duration of each draw until the outlet temperature drops to Tmin, at which time the draw is terminated. Record the average outlet temperatures as well as the mass removed. Continue this sequence of events until one hour has elapsed. If a draw is currently taking place, continue the draw until the outlet temperature reaches Tmin, and record the elasped time between the previously recorded time, at the beginning of the first draw, and the termination of this final draw as . If a draw is not taking place at the end of one hour, wait until the thermostat acts to reduce the supply of fuel to the main burner or electrical input to the upper heating element of a multiple element electric water heater, or electrical input to a water heater having a single element or multiple elements which operate simultaneously, to initiate the final draw. During the final draw, record the outlet fluid temperature beginning 15 seconds after initiating the draw and at every subsequent 5 second intervals throughout the duration of the draw until the outlet temperature drops to Tmin, at which time the draw is terminated. Record the elasped time between the previously recorded time, at the beginning of the first draw, and the termination of the final draw as hr. In either case, record the outlet temperatures and the mass removed during the final draw.

5.1.5. 24 Hour Simulated Use Test. During the simulated use test, a total of 64.3 gallons are removed. With the water heater turned off, fill the water heater with supply water and apply pressure as described in section 2.1.5. Turn on the water heater and associated heat pump unit, if present. Wait until cutout occurs at 135°F ±5°F, as specified in section 2.1.4. After the cutout occurs, measure the mean tank temperature using the temperature sensors described in section 4.5 every minute until the maximum mean storage tank temperature is achieved. The water heater may be operated through up to three successive cycles of drawing 10 gallons per draw, permitting recovery between each draw, prior to the start of the test. Record at