Installation Quick Tips - Bth 120 And 150 Gas Pressure; Adjustment Procedure; Gas Pressure; Bth120 And 150 Models - A.O. Smith Cyclone Xi Service Handbook

INSTALLATION QUICK TIPS – BTH 120 and 150 GAS PRESSURE

ADJUSTMENT PROCEDURE:

GAS PRESSURE

BTH120 AND 150 MODELS

Main line gas pressure to the water heater for natural
gas should be between a maximum of 10.5"w.c.
(2.59kPa) for natural gas, 14.0"w.c.(3.45kPa) for
propane and a minimum of 4.8w.c.(1.18kPa) for
Natural Gas, and 8.5"w.c. (2.08kPa) for Propane Gas.
Also see gas pressure specification table on page 4.
A supply gas pressure
(service regulator) must be installed on
the gas supply line within 10' (305 cm)
of the unit.
1
.Check gas line pressure with a manometer.
2.Check manifold pressure gauge (manometer)
connected to the manifold pressure tap on the gas
control valve. If full rate adjustment is required,
remove cover screw from top of the gas control valve.
Using a small screwdriver, turn adjusting screw
clockwise to increase or counterclockwise to decrease
gas pressure to obtain 4.0" w.c.(1 K pa) for natural
gas and 10.0" w.c. (2.5 kPa) for L.P. Gas.
3. Cycle the burner on and off several times to check
its operation.
4. Check the operation of the limit and operating
controls.
5. Check the vent system seams and joints and
ensure that there is no discharge of flue products into
the room.
6. Check the input rate.

HIGH ALTITUDE INSTALLATIONS

BTH 120 - 150

For appliance installation locations with elevations
above 6,500 feet (1982 meters) consult the "High
Altitude Installation" section of the owners manual.
A.O. Smith – Technical Training Department
CYCLONE Xi COMMERCIAL GAS WATER HEATER
BTH 120 thru 500 SERVICE HANDBOOK
regulator
Servicing should only be performed by a Qualified Service Agent
a. Attach a pressure gauge (manometer) to the
manifold pressure tap and refer to page 4 for correct
pressure.
b. Use this formula to "clock" the meter. Be sure
other gas consuming appliances are not operating
during this interval.
Btuh = 3600 X H/ T
T = Time in seconds to burn 1 cubic foot of gas.
(With a stopwatch read the gas meter and measure
the amount of time required for the heater to consume
1 cubic foot of gas.)
H = Heating value of gas (in Btu's per cubic foot of
gas).
Btuh = Actual heater input rate, in Btuh.
EXAMPLE: (Using BTH-150 heater)
T = 25.25 seconds
H = 1050 Btu/ft.3
BTUH = ?
Compare result to the de-rated input required for
the elevation at the installation location.
Should it be necessary to adjust the gas pressure to
the burner, to obtain the full input rate, the steps below
should be followed:
c. Remove the pressure regulator cover screw and
adjust the pressure by turning the adjusting screw with
a small screwdriver. Do not exceed 4.0" (1 kPa)
natural gas models and 10.0" w.c. (2.5kPa) on the
propane models. Clockwise to increase gas pressure
and input rate. Counterclockwise to decrease gas
pressure and input rate.
d. "Clock" the meter as in step (b) above.
e. Repeat steps (c) and (d) until the specified input
rate is achieved.
f. Turn the manual gas valve to "OFF". Replace the
pressure regulator cover screw. Remove the pressure
gauge or manometer from the manifold pressure tap.
Replace the set screw in the manifold pressure tap. If
the gas pressure regulator cannot be adjusted to give
the full input rating with sufficient gas pressure at the
valve, check to ensure the unit is equipped with the
correct orifice.
5 Ashland City, Tennessee © 2009
316586-000