A.O. Smith BTH 120-250(A) - Manual (Page 20)

20
WARNING
UNDER NO CIRCUMSTANCES SHOULD THE INPUT EXCEED THE RATE
SHOWN ON THE HEATER RATING PLATE. OVERFIRING COULD RESULT
IN DAMAGE OR SOOTING OF THE HEATER.
CATHODIC PROTECTION
CAUTION
HYDROGEN GAS CAN BE PRODUCED IN A HOT WATER SYSTEM SERVED
BY THIS HEATER THAT HAS NOT BEEN USED FOR A LONG PERIOD OF
TIME (GENERALLY TWO WEEKS OR MORE). HYDROGEN GAS IS
EXTREMELY FLAMMABLE.
To reduce the risk of injury under these
conditions, it is recommended that a hot water faucet be opened for several
minutes before using any electrical appliance connected to the hot water
system. If hydrogen is present, there will probably be an unusual sound
such as air escaping through the pipe as the water begins to flow. There
should be no smoking or open flame near the faucet at the time it is open.
PRECAUTIONS
I F THE UNIT IS EXPOSED TO THE FOLLOWING, DO NOT OPERATE HEATER
UNTIL ALL CORRECTIVE STEPS HAVE BEEN MADE BY A QUALIFIED
SERVICEMAN.
1. FLOODING TO OR ABOVE THE LEVEL OF THE BURNER OR CONTROLS
2. EXTERNAL FIRING
3. DAMAGE
4. FIRING WITHOUT WATER
5. SOOTING
NEVER OPERATE THE HEATER WITHOUT FIRST BEING CERTAIN IT IS
FILLED WITH WATER AND A TEMPERATURE AND PRESSURE RELIEF
VALVE IS INSTALLED IN THE RELIEF VALVE OPENING OF THE HEATER.
SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO SHUT
OFF, TURN OFF THE MANUAL GAS CONTROL VALVE TO THE
APPLIANCE.
GENERAL INFORMATION
POWER BURNER
The initial start-up procedure of the unit is provided on page 18.
The sequence of operation of the unit is provided on page 15.
It is important to note that the controller has a reset button on the control
box, Figure 1. The reset button is a safety device and would not normally
be used.
HIGH LIMIT
The high limit (not adjustable) is factory set to cutout at 202°F (94°C). The
controller must be manually reset by depressing the reset button on front
of the control when water temperature drops to below 160°F (71°C).
HIGH ALTITUDE INSTALLATIONS
WARNING
BTH HEATERS ARE CERTIFIED FOR USE WITHOUT MODIFICATION FOR
ALTITUDES UP TO 6500 FEET. INSTALLATIONS ABOVE 6500 FEET MAY
REQUIRE REPLACEMENT OF THE BURNER ORIFICE. CALL THE
TECHNICAL CENTER @ (800) 527-1953 FOR REQUIREMENTS.
Some gas utility companies derate their gas for altitude, making it
unneccessary to install high altitude orifices. Call the local gas or utlity
company to verify BTU content.
Due to the input rating reduction at high altitudes, the output rating of the
appliance is also reduced and should be compensated for in the sizing of
the equipment for applications.
MAINTENANCE
GENERAL
KEEP APPLIANCE AREA CLEAR AND FREE FROM COMBUSTIBLE
MATERIALS, GASOLINE AND OTHER FLAMMABLE VAPORS AND LIQUIDS.
(SEE WARNING ON PAGE 5, LOCATING THE HEATER).
Water heater maintenance includes periodic tank flushing and cleaning,
and removal of lime scale. The unit should be inspected and adjusted to
maintain proper combustion. Refer to the following table. A periodic inspection
of the venting system should be made. Where used, the water circulating
pump should be oiled.
MAINTENANCE SCHEDULE
Following are the instructions for performing some of the recommended
maintenance. Unit inspection and adjustment should be performed by a
competent technician.
COMPONENT OPERATION INTERVAL REQUIRED
Tank Sediment Monthly Flushing
Removal
Tank Lime Scale Semi UN-LIME ®
Removal Annually Delimer
Anode Inspect Semi Replace as
Rods Annually Required
Relief Valve Inspect Semi
Annually
SAE No. 20
Circulating Oiling Four Months non-detergent
Pump (1) motor oil
Clean Inlet
Blower Screen and As Required Soft Brush
Blower Wheel
Vent System Inspect Every 3 Joints should
Months be sealed
(1) If furnished with oiling provision.
TABLE 4
GAS SUPPLY SPECIFICATIONS
Natural Gas Natural Gas L.P. Gas
Max. Gas Supply Pressure W.C. 12.0 12.0 14.0
(3 kPa) (3 kPa) (3.45 kPa)
Nominal Gas Supply Press. W.C 7.0 7.0 11.0
(1.74 kPa) (1.74 kPa) (2.74 kPa)
Minimal Gas Supply Press. W.C. 5.0 4.5 11.0
(1.25 kPa) (1.12 kPa) (2.74 kPa)
Manifold Press. W.C. 4.0 3.5 10.0
(1 kPa) (872 kPa) (2.5 kPa)
BTH 120 BTH 150 BTH 120,
& 250 & 199 150 & 199