A.O. Smith TC-049-R2 manual Technical Bulletin, Service Handbook, Capacity, Deplete

RESIDENTIAL GAS AND ELECTRIC WATER HEATER

SERVICE HANDBOOK

TECHNICAL BULLETIN

BULLETIN 35

NOT ENOUGH HOT WATER - GAS

CAUSE

Not enough hot water complaints are becoming more frequent in the water heater industry. This increase was triggered when changes required by our regulatory agencies were implemented. For example, heaters are now factory preset at a lower temperature and inlet tubes have been shortened. While lower temperatures settings reduce the burn rate, and shorter dip tubes guard against stacking, both affect the amount of hot water a water heater can supply. The following test will help determine if a water heater is supplying the intended amount of hot water and will help pinpoint any problems that exist.

TEST	Please read all the steps of the test prior to beginning. If you feel uncomfortable
	performing any of these steps, contact a service person to conduct this test for you.
STEP 1	At the faucet nearest to the water heater, time (in seconds) how long it takes to fill a
	1 gallon bucket (flow rate).
	Gallon per minute (gpm) = 60 seconds / seconds to fill a 1 gallon bucket
	If the bucket fills in: 10 sec = 6 gpm
	12 sec = 5 gpm
	15 sec = 4 gpm
	20 sec = 3 gpm
	24 sec = 2.5 gpm
STEP 2	Turn thermostat dial on the water heater so the arrow points to “A” position.
STEP 3	Run about 15 gallons of hot water from the nearest faucet. Shut water off.
STEP 4	Water heater should complete heating 15 gallons in approximately 20-35 minutes.
STEP 5	At a nearby faucet using a candy thermometer, measure the hot water temperature.
STEP 6	The temperature should fall between 120°F to 140°F.
STEP 7	Continue running the hot water until 60% of the tank capacity is depleted:
	CAPACITY	DEPLETE
	30 gallons	18 gallons
	40 gallons	24 gallons
	50 gallons	30 gallons
	75 gallons	45 gallons
	100 gallons	60 gallons
STEP 8	At the same faucet using a candy thermometer, measure the water temperature.
STEP 9	The temperature should be about 30°F below the temperature in step 6.

THE FIX

Step 6 - if the temperature was not within range, check the thermostat. Step 9 - if more than 30 °F was lost, check the dip tube.

A.O. Smith Water Products Company	55	Training Department
©2002		Ashland City, Tennessee