Cathodic Protection; Precautions; General Information; Power Burner - A.O. Smith BTH 120-250(A) Installation & Operating Instructions Manual

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

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

IF 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).
TABLE 4
GAS SUPPLY SPECIFICATIONS
Max. Gas Supply Pressure W.C.
Nominal Gas Supply Press. W.C
Minimal Gas Supply Press. W.C.
Manifold Press. W.C.
WARNING
CAUTION
BTH 120 BTH 150 BTH 120,
& 250 & 199 150 & 199
Natural Gas Natural Gas
12.0 12.0
(3 kPa) (3 kPa) (3.45 kPa)
7.0 7.0
(1.74 kPa) (1.74 kPa) (2.74 kPa)
5.0 4.5
(1.25 kPa) (1.12 kPa) (2.74 kPa)
4.0 3.5
(1 kPa) (872 kPa) (2.5 kPa)

HIGH ALTITUDE INSTALLATIONS

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.
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.
Following are the instructions for performing some of the recommended
maintenance. Unit inspection and adjustment should be performed by a
competent technician.
COMPONENT
Tank
Tank
Anode
Rods
Relief Valve
Circulating
Pump (1)
L.P. Gas
14.0
Blower
11.0
11.0
Vent System
10.0
(1) If furnished with oiling provision.
20
WARNING

MAINTENANCE

GENERAL

MAINTENANCE SCHEDULE

OPERATION INTERVAL
Sediment Monthly
Removal
Lime Scale Semi
Removal Annually
Inspect Semi
Annually
Inspect Semi
Annually
Oiling Four Months non-detergent
Clean Inlet
Screen and As Required
Blower Wheel
Inspect Every 3
Months
REQUIRED
Flushing
UN-LIME ®
Delimer
Replace as
Required
SAE No. 20
motor oil
Soft Brush
Joints should
be sealed