John Wood JW375T75N-AV, Instruction Manual

Page: 21 / 36

21
CHECKING GAS INPUT
With this heater in operation, determine whether it is receiving the
full rated input of gas. This may be done by timing the gas meter
and measuring gas pressure with a gauge or manometer. When the
heater is operating at full capacity (full gas input) it should consume
approximately 1 cubic foot of gas in the time shown in Table 5.
TABLE 5. INPUT CHECK TIME REQUIRED
TO CONSUME 1 CU. FT. OF GAS
Models Type of Gas BTU Per
Cu. Ft.
Approx. Time Required To
Consume 1 Cu. Ft. of Gas
JW375T75N-AV
JW375T75P-AV
Natural
Propane
1050
2500
50.3 sec. 119. 8 sec.
Use this formula to “clock” the meter. Be sure that other gas
consuming appliances are not operating during this interval.
3,600 X H = Btu/Hr
T
T = Time in seconds needed to burn one cubic foot of gas.
H = Heating value of gas in Btu’s per cubic foot of gas.
Btu/Hr = Actual heater input rate.
Example: (Using BT-80 heater)
T = 50.3 seconds/ft
3
H = 1,050 Btu/ft
3
(natural gas)
Btu/Hr = ?
3,600 X 1,050 = 75,100 Btu/Hr (22.0 kW)
50.3
Compare the actual input rate to that given on the heater’s rating
plate. In the example, the BT-80’s full input rate should be 75,100
Btu/Hr for natural gas.
Because of the suddenness and amount of water, condensation
water may be diagnosed as a “tank leak”. After the water in the tank
warms up (about 1-2 hours), the condition should disappear.
Do not assume the water heater is leaking until there has been
enough time for the water in the tank to warm up.
An undersized water heater will cause more condensation. The water
heater must be sized properly to meet the family’s demands for hot
water including dishwashers, washing machines and shower heads.
Excessive condensation may be noticed during the winter and early
spring months when incoming water temperatures are at their lowest.
Good venting is essential for a gas fired water heater to operate properly
as well as to carry away products of combustion and water vapor.
SMOKE/ODOR
It is not uncommon to experience a small amount of smoke and odor
during the initial start-up. This is due to burning off of oil from metal
parts, and will disappear in a short while.
STRANGE SOUNDS
Possible noises due to expansion and contraction of some metal
parts during periods of heat-up and cool-down do not necessarily
represent harmful or dangerous conditions.
Condensation causes sizzling and popping within the burner area
during heating and cooling periods and should be considered normal.
See “Condensation” in this section.
OPERATIONAL CONDITIONS
SMELLY WATER
In each water heater there is installed at least one anode rod (see
parts section) for corrosion protection of the tank. Certain water
conditions will cause a reaction between this rod and the water.
The most common complaint associated with the anode rod is one
of a “rotten egg smell” in the hot water. This odor is derived from
hydrogen sulfide gas dissolved in the water. The smell is the result
of four factors which must all be present for the odor to develop:
a. A concentration of sulfate in the supply water.
b. Little or no dissolved oxygen in the water.
c. A sulfate reducing bacteria which has accumulated within the
water heater (this harmless bacteria is nontoxic to humans).
d. An excess of active hydrogen in the tank. This is caused by the
corrosion protective action of the anode.
Smelly water may be eliminated or reduced in some water heater
models by replacing the anode(s) with one of less active material,
and then chlorinating the water heater tank and all hot water
lines. Contact the local water heater supplier or service agency
for further information concerning an Anode Replacement Kit and
this chlorination treatment.
If the smelly water persists after the anode replacement and chlorination
treatment, we can only suggest that chlorination or aeration of the water
supply be considered to eliminate the water problem.
Do not remove the anode leaving the tank unprotected. By doing
so, all warranty on the water heater tank is voided.