4.6 Total per-cycle gas dryer energy consumption expressed in kilowatt-hours. Calculate the total gas dryer energy consumption per cycle, Ecg, expressed in kilowatthours per cycle and defined as: Ecg=Ege+(Eg/3412 Btu/k Wh) [46 FR 27326, May 19, 1981] APPENDIX E TO SUBPART B OF PART 430-UNIFORM TEST METHOD FOR MEASURING THE ENERGY CONSUMPTION OF WATER HEATERS 1. DEFINITIONS 1.1 "Cutout" means the moment in time when a water heater thermostat has acted to reduce the energy or fuel input to the heating elements or burners to a minimum. 1.2 "Design Power Rating" means the nominal power rating that a water heater manufacturer assigns to a particular design of water heater heating element, expressed in kilowatts. 1.3 "Heat Trap" means a device which can be integrally connected, or independently attached, to the hot or cold water pipe connections of a water heater such that the device will develop a thermal or mechanical seal to minimize the recirculation of water due to natural thermal convection between the water heater tank and its water supply pipes and thereby reduce the heat loss to the environment from the hot water stored in the water heater. 1.4 "Recovery Efficiency" means the ratio of the heat imparted to the water to(a) in the case of an electric water heater, the energy input to the heating elements during the period that the water temperature is raised from the inlet temperature to the final temperature with the tank filled to capacity. (b) in the case of a gas or oil water heater, the heat content of the fuel consumed by the burners during the period that the water temperature is raised from the inlet temperature to the final temperature with the tank filled to capacity. 1.5 "Standby loss" means the ratio of the heat loss per hour to the heat content of the stored water above room temperature. 2. TEST CONDITIONS 2.1 Installation. Install the water heater according to the manufacturer's directions on a 4-inch-thick plywood platform supported by three 2 x 4-inch runners. For water heaters without integral heat traps and with vertical inlet and outlet pipe connections, install the inlet and outlet piping with heat traps at the inlet and outlet ports. Such heat traps may be made using pipe fit tings such as elbows connected in such a fashion that the inlet and outlet piping make vertically upward runs just before turning downward to connect to the inlet and outlet ports. For water heaters with integral heat traps or with horizontal inlet and outlet pipe connections, install the inlet and outlet piping in any convenient fashion. Sufficient clearance shall be allowed between the water heater surface and the piping (including heat traps, if any) so that when the piping is insulated as specified below, the insulation does not contact any water heater surface except at the location where the pipe connections penetrate the water heater jacket. Insulate the water heater inlet and outlet piping (including heat traps, if any) for a length of four feet from the connection at the water heater with a material having a thermal resistance (R) value of not less than 4° F/Btu/ft2hr 2.2 Flue requirements for gas and oil water heaters. 2.2.1 Flue requirements for gas water heaters. For a gas water heater having a vertically discharging draft hood outlet, a 5 foot vertical flue 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 a gas 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 5 foot length of flue pipe shall be connected to the elbow and oriented to discharge vertically upward. Perform all tests with the natural draft established by this length of flue pipe. Direct vent gas water heaters should be installed with venting equipment as specified in the manufacturer's instructions; however, the vertical length of the flue pipe shall be no greater than 5 feet. 2.2.2 Flue requirements for oil water heaters. For an oil fueled water heater, establish a draft at the flue collar equivalent to at least 0.02 inch of water column during periods of burner firing. For an oil water heater having a vertically discharging draft hood outlet, establish the draft by using a sufficient length of flue pipe connected to the water heater flue outlet and directed vertically upward. For an oil 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 flue pipe sufficient to establish the draft shall be connected to the elbow fitting and oriented to discharge vertically upward. Direct vent oil water heaters should be installed with venting equipment as specified in the manufac turer's instructions. When ceiling height limits the use of a sufficient length of vertical flue pipe for an oil water heater, a mechanical draft inducer may be used during periods of burner firing to establish the specified draft at the flue collar. 2.3 Water supply. During the entire test maintain the water supply to the water heater inlet at a temperature of between 68 and 72° F., and at a gauge pressure of between 40 pounds per square inch and the maximum pressure specified by the manufacturer for the water heater under test. If the water supply pressure varies outside of these limits during testing, the heater shall be isolated by use of a shut-off valve in the supply line with an expansion tank installed in the supply line downstream of the shutoff valve. There shall be no shut-off means between the expansion tank and the water heater inlet. 2.4 Energy Supply. 2.4.1 Electrical supply. For an electric water heater and for the auxillary electrical system, if any, of an oil or gas water heater, maintain the electrical supply voltage to within ±1 percent of the center of the voltage range specified by the water heater manufacturer on the water heater nameplate throughout the entire operating portion of each test. 2.4.2 Gas supply. 2.4.2.2 Natural gas. For gas water heater utilizing natural gas, maintian the gas supply at a normal inlet test pressure immediately ahead of all controls at 7 to 10 inches of water column. If the water heater is equipped with a gas appliance pressure regulator, the regulator outlet pressure at the normal test pressure shall be approximately that recommended by the manufacturer. All burners shall be adjusted to achieve an hourly Btu rating that is within ±2 percent of the hourly Btu rating specified by the manufacturer. Use natural gas with a higher heating value of approximately 1,025 Btu per standard cubic foot. Determine the actual higher heating value, Hn, in Btu per standard cubic foot, for the natural gas to be used in the test, with an error no greater than ±1 percent, and use that value for all calculations included herein. Alternatively, the test can be conducted using "bottled" natural gas of a higher heating value of approximately 1,025 Btu per standard cubic foot as long as the actual higher heating value of the bottled natural gas has been determined with an error no greater than 1 percent as certified by the supplier. 2.4.2.2 Propane gas. For a gas water heater utilizing propane, maintain the gas supply at a normal inlet test pressure immediately ahead of all controls at 11 to 13 inches of water column. If the water heater is equipped with a gas appliance pressure regulator, the regulator outlet pressure at normal test pressure shall be approximately that recommended by the manufacturer. All burners shall be adjusted to achieve an hourly Btu rating that is within ±2 percent of the hourly Btu rating specified by the manufacturer. Use propane with a higher heating value of approximately 2,500 Btu per standard cubic foot. Determine the actual higher heating value, Hp, in Btu per standard cubic foot, for the propane to be used in the test, with an error no greater than 1 percent, and use that value for all calculations included herein. Alternatively, the test can be conducted using "bottled" propane of a higher heating value of approximately 2,500 Btu per standard cubic foot as long as the actual higher heating value of the bottled propane has been determined with an error no greater than ±1 percent as certified by the supplier. 2.4.3 Oil supply. For an oil water heater utilizing fuel oil, maintain an uninterrupted supply of fuel oil to the water heater during the entire operating portion of the test cycle. Use fuel oil with a heating value of approximately 138,500 Btu per gallon. Determine the actual heating value, H., in Btu per gallon for the fuel oil to be used in the test with an error no greater than ±1 percent, and use that value for all calculations included herein. Alternatively, the tests can be conducted using a tested fuel oil with a certified higher heating value of approximately 138,500 Btu per gallon as long as the actual higher heating value of the test fuel oil has been determined with an error of no greater than ±1 percent as certified by the supplier. 2.5 Thermocouple installation. Install six thermocouples inside the water heater tank. Position each thermocouple measuring junction along a vertical line at the level of the center horizontal plane of each of six non-overlapping sections of approximately equal volume from the top to the bottom of the tank such that each thermocouple is surrounded by water and as far as possible from any heating element, anodic protective device, or a water tank or flue wall. The anodic protective device may be removed in order to install the thermocouples and all testing may be carried out with the device removed. Install thermocouples in both the cold-water inlet pipe and the hot-water outlet pipe not more than six inches from the connections to the water heater, or where those connections are inaccessible, at the closest accessible point to those connections. Install in the test room a thermocouple with junction shielded against direct radiation from the water heater and positioned at the vertical mid-point of the heater at a perpendicular distance of approximately 24 inches from the surface of the water heater jacket. Provide an associated temperature measurement and indicator system to assure that the temperature indi cated for the thermocouple location is within ±1° F. of the actual temperature at that location. 2.6 Setting the tank thermostat. Starting with a tank of unheated water, initiate normal operation of the water heater. After cutout, determine whether the maximum value of the mean tank temperature is within the range of 160° F. +5° F. if not, turn off the water heater, adjust the thermostat, empty the tank and refill with unheated water, then initiate normal operation of the water heater, and once again determine the maximum mean tank temperature after cutout. Repeat this sequence until the maximum mean tank temperature after cutout is within the range of 160° F. ±5°F., at which time the thermostat is properly set. 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 160° F. +5° F. as measured by the topmost tank thermocouple after cutout. The thermostat which controls the lower heating element shall then be set to yield a maximum mean tank temperature of 160° F. ±5° F. after cutout. 2.7 Fuel or energy consumption measurement. Install one or more instruments which measure, as appropriate, and with an error no greater than ±1 percent, the quantity of electrical energy, natural gas, propane or fuel oil consumed by a water heater. Electrical energy consumption is to be expressed in units of kilowatt-hours. Natural gas and propane consumption shall be expressed in units of standard cubic feet, i.e., measured cubic feet corrected to standard conditions of 60° F. temperature and 30 inches of mercury column pressure. Fuel oil consumption is to be expressed in units of gallons. Also install one or more instruments which measure, as appropriate, and with an error no greater than ±1 percent, the rate of electrical energy, natural gas, propane or fuel oil consumption by a water heater. The rate of electrical energy consumption shall be expressed in units of kilowatts. The rate of natural gas and propane consumption shall be expressed in units of standard cubic feet per hour. The rate of fuel oil consumption shall be expressed in units of gallons per hour. 2.8 Room ambient temperature. Maintain the ambient air temperature of the test room between 65° F. and 85° F. at all times during the test, as measured according to section 3.5. The ambient air temperature during these tests shall not vary more than ±7° F. from the average ambient air temperature determined as the arithmetic average of the air temperatures measured periodically at intervals no greater than 15 minutes throughout the duration of the test. 3. TEST PROCEDURES AND MEASUREMENTS 3.1 Tank storage capacity. Determine the storage capacity, V, of the water heater under test, in gallons, according to the method specified in section 2.26 of the American National Standard for Gas Water Heaters, Volume I, designated ANS Z21.10.1-1975. 3.2 Power input determination. 3.2.1 Power input determination for gas and oil water heaters and electric water heaters with other than immersed heating elements. Initiate normal operation of the water heater, and by using the appropriate instrumentation specified in section 2.7 and the appropriate fuel heating values of section 2.4, determine the power input, P, to the main burners (including pilot light power, if any) or heating elements of the water heater under test, in Btu per hour or kilowatts, as appropriate. In addition, determine the power input, p, to any auxiliary electrical system of a gas or oil water heater when the main burners are in operation, in kilowatts; and the power input, p., to any auxiliary electrical system of a gas or oil water heater when the main burners are not in operation, in kilowatts. 3.2.2 Power input determination for electric water heaters with immersed heating elements. The power input, P, to the heating element of an electric water heater with one immersed heating element shall be taken to be the design power rating of the heating element. For an electric water heater with dual immersed heating elements, the power input, P, to the heating elements shall be taken to be the arithmetic mean of the design power ratings of the heating elements, if, in characteristic operation of the water heater, only one heating element will be energized at any time; otherwise, P shall be taken to be the sum of the design power ratings of the heating elements. 3.3 Recovery efficiency. 3.3.1 Recovery efficiency for gas and oil water heaters and electric water heaters with other than immersed heating elements. With the water heater turned off, fill the tank with water and eliminate any residual air remaining in the tank. If the mean tank temperature is constant and within 70° F.±2° F., record the mean tank temperature, initiate normal operation of the water heater, and begin measuring the fuel or energy flow to the burners (including pilot light fuel if any) or heating elements of the water heater using the appropriate instrumentation specified in section 2.7 After cutout determine the maximum mean tank temperature and record the total fuel flow, Qr, for a gas or oil water heater, or the total electrical energy flow, Zr, to the heating elements of an electric water heater, from initiation to cutout. Record the temperature dif ference, AT1, obtained by subtracting the initial from the final maximum mean tank temperature. 3.3.2 Recovery efficiency for electric water heaters with immersed heating elements. The recovery efficiency for electric water heaters with immersed heating elements is derived from the results of the standby loss tests of section 3.4.2. 3.4 Standby loss. 3.4.1 Standby loss for gas and oil water heaters and electric water heaters with other than immersed heating elements. Establish normal water heater operation within the maximum mean tank temperature within the range specified in section 2.6 and with all air eliminated from the tank. Begin the standby loss test immediately after cutout. At the beginning of the standby loss test record the time, the mean tank temperature, the ambient air temperature, and begin measuring the fuel or energy flow to the burners (including pilot light fuel if any) or heating elements of the water heater using the appropriate instrumentation specified in section 2.7. At the end of the first 15 minute interval and at the end of each subsequent 15 minute interval following the beginning of the test, record the mean tank temperature and the ambient air temperature. Continue these measurements until the end of a 48 hour period unless a main heating element or burner is on at that time, in which case, continue these measurements until the first subsequent cutout. When the test is terminated, record the total fuel flow, Q., for a gas or oil water heater, or the total electrical energy flow, Z,, to the heating elements of an electric water heater, from the beginning to the end of the test period, the final mean tank temperature, the final ambient air temperature, and the time duration, t, of the standby loss test, in hours rounded off to the nearest tenth of an hour, which elapsed from the beginning to the end of the test period. Calculate the average of the recorded values of the mean tank temperatures and of the ambient air temperatures taken at the end of each time interval, including in each case the initial and final values. Determine the difference, AI, between these two averages by subtracting the latter from the former, and the difference, AI, between the final and initial mean tank temperatures by subtracting the latter from the former. 3.4.2 Standby loss for electric water heaters with immersed heating elements. All water heaters to be tested must be equipped with immersed heating elements that have a design power rating of 4,500 watts unless such a design power rating exceeds the maximum design power rating specified by the manufacturer for the water heater to be tested, in which case the standby loss test will be conducted with the water heater equipped with immersed heating elements of a design power rating equal to the manufacturer's specified maximum design power rating. All water heaters capable of operating with dual immersed heating elements will be equipped and tested with dual immersed heating elements of equal design power rating in accordance with the provisions specified above. Tests shall be conducted in accordance with the same procedures as those specified in section 3.4.1. 3.5 Room temperature measurement. Room temperature wherever specified shall be the temperature determined by using the test room thermocouple described in section 2.5. 3.6 Mean tank temperature measurement. Mean tank temperature, the average temperature of the water in a water heater tank, whever specified shall be the mean of the temperatures determined by using the six water heater tank thermocouples described in section 2.5. 3.7 First hour rating water draw test. Establish normal water heater operation with the maximum mean tank temperature within the range specified in section 2.6 and with all air eliminated from the tank. Begin the first hour rating water draw test immediately after a cutout by recording the hot water outlet water temperature, recording the time, and withdrawing water from the water heater through the hot water outlet at a rate of 5.0±0.25 gallons per minute. Interrupt electrical power to the heating elements or fuel to the main burner of the water heater to prevent their operation during this test. Collect all of the water withdrawn from the water heater during the test in a suitable container for the purpose of determining its weight at the conclusion of the test. Alternatively, a water flow meter may be used to measure the volume of water withdrawn from the water heater directly. Beginning 15 seconds after the start of the test and at every subsequent 15 second interval throughout the duration of the water draw, record the outlet water temperature. For the purposes of this test, the maximum recorded temperature shall be referred to as the initial outlet water temperature, T.. Monitor the functioning of the water heater thermostats and record the time that a thermostat on the water heater acts to operate a heating element or the main burner. Continue the withdrawal of water until the outlet water temperature drops to a value 20°F below the initial water temperature, at which time terminate the withdrawal. Determine the weight of the water withdrawn, W, in pounds measured with an error no greater than 2 percent, or the volume of water withdrawn, G, in gallons measured with an error no greater than 2 percent. Determine the arithmetic mean of the outlet water temperature readings re k=8.25 Btu per gallon F., the nominal specific heat of water. V tank capacity, determined in accordance with section 3.1, expressed in gallons. AT, difference between the initial and final mean tank temperatures, determined in accordance with section 3.3.1, expressed in °F. Q=total fuel flow in the recovery test, determined in accordance with section 3.3.1, expressed in appropriate units. H=higher heating value for the appropriate fuel type, Hn, Hp, OR Ho, as determined in accordance with section 2.4, expressed in appropriate units. 4.1.2 Recovery efficiency for electric water heaters with other than immersed heating elements. For an electric water heater with other than immersed heating elements, calculate the recovery efficiency, Er, expressed as a dimensionless quantity and defined as: Er=(kx VXAT1/ZX3,412 Btu/kWh), where k, V, and AT, are as defined in section 4.1.1 Zr-total electrical energy flow to the heating elements in the recovery test, determined in accordance with section 3.3.1, expressed in kilowatt-hours. 4.1.3 Recovery efficiency for electric water heaters with immersed heating elements. For an electric water heater with immersed heating elements, calculate the recovery efficiency, Er, expressed as a dimensionless quantity and defined as: E-1-(Sxk×V×▲T2/P×3,412 Btu/kWh), where k and V are as defined in section 4.1.1 S=standby loss, as calculated in section 4.4.2. k, V, and H are as defined in section 4.1.1 Er is as calculated in section 4.1.1 Q.-total fuel flow in the standby loss test, determined in accordance with section 3.4.1, expressed in appropriate units. AT3 difference between the average value of the mean tank temperature and the average value of the ambient air temperature during the standby loss test, determined in accordance with section 3.4.1, expressed in ° F. AT, difference between the initial and final mean tank temperatures, determined in accordance with section 3.4.1, expressed in ° F. t=duration of the standby loss test, deter mined in accordance with section 3.4.1, expressed in hours. 4.2.2 Standby loss for electric water heaters. For an electric water heater, calculate the standby loss, S, expressed in hour – 1 and defined as: S=(Z, X3,412 Btu/kWh/k×V×aT,×t) – (AT./AT.xtx Er)* where k and V are as defined in section 4.1.1. Z1 = total electrical energy flow to the heating elements in the standby loss test, determined in accordance with section 3.4.1 for electric water heaters with other than immersed heating elements, or section 3.4.2 for electric water heaters with immersed heating elements, expressed in kilowatt-hours. AT, difference between the average value of the mean tank temperature and the average value of the ambient air temperature during the standby loss test, determined in accordance with section 3.4.1 for electric water heaters with other than immersed heating elements, or section 3.4.2 for electric water heaters with immersed heating elements, expressed in kilowatt-hours. AT.=difference between the initial and final mean tank temperatures, determined in accordance with section 3.4.1 for electric water heaters with other |