A.O. Smith BTH 300A - Manual (Page 22)

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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
IF THE UNIT IS EXPOSED TO OR EXHIBITS 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 DAMAGE
3. FIRING WITHOUT WATER
4. 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 19.
The sequence of operation of the unit is provided on page 16.
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 2000 FEET.
INSTALLATIONS ABOVE 2000 FEET MAY REQUIRE
REPLACEMENT OF THE BURNER ORIFICE. CALL THE
TECHNICAL INFORMATION CENTER AT (800) 527-1953 FOR
REQUIREMENTS.
Some gas utility companies derate their gas for altitude, making
it unnecessary to install high altitude orifices. Call the local gas
or utility 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 C L E A R A N D F R E E 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.
TABLE 4.
GAS SUPPLY SPECIFICATIONS Nat. Gas LP Gas
Max. Gas Supply Pressure W.C. 11.00 14.00
Max. Gas Supply Pressure kPa 2.74 3.49
Nominal Gas Supply Pressure W.C. 7.00 11.00
Nominal Gas Supply Pressure kPa 1.74 2.74
Minimum Gas Supply Pressure W.C.* 6.20 11.0
Minimum Gas Supply Pressure kPa* 1.54 2.74
Manifold Gas Supply Pressure W.C. 5.00 10.0
Manifold Gas Supply Pressure kPa 1.25 2.49
* Minimum pressure for purposes of rate adjustment
HIGH ALTITUDE ADJUSTMENTS
FOR BTH 300 AND 400
NATURAL GAS
ELEVATION (ft./m) MANIFOLD SETTING (in W.C./Kpa)
Up to 2,000 ft./610 m. 5.0/1.25 - NO ADJUSTMENT
2,001 - 3,000 ft./914 m. 4.8/1.19
3,001 - 4,000 ft./1,219 m. 4.7/1.17
4,001 - 5,000 ft./1,524 m. 4.6/1.14
5,001 - 6,000 ft./1,829 m. 4.5/1.12
6,001 - 7,000 ft./2,134 m. 4.5/1.12
7,001 - 8,000 ft./2,438 m. 4.4/1.09
PROPANE GAS
ELEVATION (ft./m) MANIFOLD SETTING (in W.C./Kpa)
Up to 2,000 ft./610 m. 10.0/2.49 - NO ADJUSTMENT
2,001 - 3,000 ft./914 m. 9.9/2.46
3,001 - 4,000 ft./1,219 m. 9.8/2.44
4,001 - 5,000 ft./1,524 m. 9.7/2.41
5,001 - 6,000 ft./1,829 m. 8.4/2.09
6,001 - 7,000 ft./2,134 m. 7.2/1.79
7,001 - 8,000 ft./2,438 m. 6.1/1.52