Filter
Top Products
RESIDENTIAL GAS, NON POWER VENTED, WATER HEATER
SERVICE HANDBOOK
State Water Heater Technical Training Department
© 2004 Ashland city, TN
31
TECHNICAL 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 120F to 140F.
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 30F 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.