Reliant FVIR GAS WATER HEATER Technical Information PDF herunterladen (Seite 3)

RESIDENTIAL GAS AND ELECTRIC WATER HEATER

TROUBLESHOOTING and SERVICE HANDBOOK

RELIANCE Water Heater Company Technical Training Department

GENERAL SECTION

MISCELLANEOUS INFORMATION

Draw efficiency (draw down) is the quantity of hot water available to the consumer before the

outlet water temperature decreases 25 degrees F. A 40 gallon water heater will typically provide

70% (28 gallons) of this “usable” hot water. The burner or elements are allowed to operate during

this test. Incoming, cold water mixes the remaining stored water below this 25 degree limitation.

Energy Factor is an indicator of the combined thermal efficiency and standby efficiency of a

water heater. The higher the energy factor, the more efficient the water heater will be.

Recovery rate is the amount of water that is heated to a set temperature, per hour. An example

might be that a water heater has a recovery rate of 30 gallons of water per hour at 80 degree F.

(Fahrenheit) temperature rise.

“R” Value is a measure of the resistance of a substance to heat flow.

Thermal efficiency is approximately the amount of generated BTU (British Thermal Units),

which enters the water. A percentage of the total BTU passes out through the vent piping.

Temperature rise is the increase in the temperature from its coldest “inlet” water temperature to

the desired hot (outlet) setting. Typically this is assumed to be 40 degrees entering water, 120

degrees desired stored water or 80 degrees “temperature rise.”

Standby efficiency – the water heater’s ability to contain heat in the tank. A minimum of tank

water heat loss per hour is desired.

Sample: temperature change

= Btu/h loss/ square foot of tank surface

“R” value

Water cannot (for all practical purposes) be compressed.

Water expands when it is heated.

Water Hammer – is a concussion of moving water against the sides of a containing pipe or vessel

on a sudden stoppage of flow.

EX: 1/2 “copper pipe, 5GPM flow (7.2ft/sec.) – stop. Pressure rise of approximately 412 PSI.

3/4” copper pipe, 5GPM flow (3.3ft/sec) – stop. Pressure rise of approximately 188 PSI

Minerals and gases will separate from water as temperature increases.

Formulas:

BTU (British Thermal Unit) is the heat required to raise 1 pound of water 1 F

BTU divided by 3,413 = Kilowatts

To convert from Fahrenheit to Celsius: (° F – 32) times 5/9, or .556, equals degrees C.

One gallon of 120 F (49 C), water weighs approximately 8.25 pounds.

Pounds X .45359 = Kilogram

Gallons X 3.7854 = Liters

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Reliant FVIR GAS WATER HEATER Technical Information Seite 3