A.O. Smith BTC 151, Instruction Manual

Page: 23 / 52

23
prior to start up
Installation and start up of this water heater requires abilities
and skills equivalent to that of a licensed tradesman in the field
involved, see Qualifications on page 6.
Do not place the water heater in operation if any part has been
under water. Immediately call a qualified service technician to
inspect the water heater and to replace any part of the control
system and any gas control which has been under water.
Light the water heater in accordance with the Lighting and
Operation Instruction label on the water heater and in this manual
on page 25.
The water heaters covered by this manual are equipped with
an electronic control system that automatically sequences the
Blower, the Igniter, the 24 VAC gas Valve, Burner ignition,
and flame sensing. The control system will lock out after three
unsuccessful ignition attempts.
Before attempting start up, thoroughly study and familiarize
yourself with the exact Sequence Of Operation, see the written
Sequence Of Operation on page 25 and the Sequence Of
Operation Flow Chart on page 26.
Be certain that the water heater is full of water, that air is purged
from the gas and water lines and that there are no leaks in the
gas and water lines. Ensure all inlet water valves are open.
filling the water heater
Follow these steps to fill the water heater prior to start up.
1. Close the heater drain valve.
2. Open a nearby hot water faucet to permit the air in the system
to escape.
3. Fully open the cold water inlet valve allowing the piping and
water heater to fill with water.
4. Close the hot water faucet opened in Step 2 as water starts
to flow.
supply gas line purging
Fire or Explosion Hazard
Read instruction manual before
installing, using or servicing
water heater.
To avoid risk of fire or explosion purge discharge must not
enter into confined areas or spaces where ignition can occur.
The area must be well ventilated and all sources of ignition
must be deactivated or removed.
Gas line purging is required with new piping or systems in
which air has entered.
Use only the gas shown on the water heater rating label.
Keep ignition sources away from faucets after extended
periods of non-use.
1. Close the Main gas Shutoff Valve, see Figure 20.
2. Purge all air from the supply gas line up to the water heater’s
Main gas Shutoff Valve.
3. When all air has been purged from the supply gas line, tighten
all supply gas line connections.
4. Check for gas leaks, see gas Line Leak Testing on page 22
and repair any leaks found.
start up
initial start up
required test equipment
u-tube manometer, pressure gauge, or digital manometer.
Recommended range: 20” W.C. (5 kPa).
note: All test equipment must be acclimated to ambient
temperature before calibration and use.
preparation
1. Adjust the thermostat to the lowest temperature setting.
2. Turn the water heater’s on/off switch to the “off” position.
3. Close the Main gas Shut Off Valve, see Figure 20.
4. Wait five (5) minutes for any residual gas to clear.
5. Connect the manometer to the supply gas pressure test port.
6. Open the Main gas Shutoff Valve.
7. Measure and record the supply gas pressure, this is a “static”
supply gas pressure reading; while the water heater is not firing.
lighting the water heater
1. Turn the water heater’s on/off switch to the “on” position.
2. Adjust the thermostat to the desired water temperature.
3. Record the supply gas pressure when the 24 VAC gas Valve is
energized and the Burner is operating. This is a “dynamic” gas
pressure reading; while the water heater is firing.
4. Compare the actual supply gas pressure reading recorded
above to the required minimum/maximum values given in
Table 3 on page 8. Adjust supply gas pressure as necessary,
see the instructions that follow.
5. After the supply gas pressure adjustments are complete, turn
off the water heater and close the Main gas Supply Shut Off
Valve. Disconnect the manometer and install the pipe plug in
the Supply gas Pressure Port.
supply gas pressure adjustment
Fire and Explosion Hazard
Turn off gas lines during installation.
Contact a qualified installer or service
agency for installation and service.
Excessive gas pressure to gas valve can
cause serious injury or death.
Do not use water heater with any gas
other than the gas shown on the rating
label.
supply gas pressure shall be measured while the water heater
is not firing (static pressure) and while the water heater is firing
at full capacity (dynamic pressure).
If the supply gas pressure to the water heater is not between
the required minimum and maximum values given in Table 3
on page 8 adjust the supply gas regulator as necessary. Adjust
the supply gas regulator(s) per the regulator manufacturer’s
instructions to achieve the required “static” and “dynamic”
supply gas pressure.
multiple appliance installations:
In multiple water heater installations or in installations where
the installed water heater(s) share a common gas supply main
with other gas fired appliances; the supply gas pressures shall
be measured at each water heater with all gas fired appliances
connected to a common main firing at full capacity.