John Wood Commercial - 300-400K BTU - Manual (Page 49)

49
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
beginning on page 52.
The water heaters covered by this manual are equipped with
an electronic control system (see page 41) which automatically
sequences the Combustion blower, pre and post purging of
the combustion chamber, the Hot Surface Igniter, the 24 VAC
gas Valve, Main 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 49 and the Sequence Of
Operation Flow Chart on page 55.
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 52 on page
36.
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 37,
and repair any leaks found.
initial start up
reQuired test eQuipment
• Two u-tube manometers, recommended ranges; 0-14” W.C.
(0-3.5 kPa) and 0-35” W.C. (0-8.7 kPa) or pressure gauges.
• Two digital manometers can be used in place of u-tube
manometers or pressure gauges. recommended ranges;
-14.00 to +14.00” W.C. (0-3.5 kPa) resolution 0.01” W.C.
and 0-35” W.C. (0-8.7 kPa) resolution 0.10” W.C.
note:
All test equipment must be acclimated to ambient
temperature before calibration and use.
preparation
1. using the control system menus, change the Operating Set
Point to the lowest temperature setting, see Operating Set
Point And Differential Adjustment on page 44.
2. Turn the water heater’s on/off switch to the “off” position.
3. Close the Main gas Shut Off Valve, see Figure 52 on page 36.
4. Push in the gas control knob slightly and turn to the
“off”position, see Figure 56 on page 50.
5. Wait five (5) minutes for any residual gas to clear.
6. Connect one manometer (higher range) to an available test
port on the supply gas line at the water heater. There is a
1/8" NPT Tee fitting and pipe nipple installed for the Low gas
Pressure switch on the inlet side of the 24 VAC gas Valve
with a 1/8" NPT plug for this purpose. For AJWSH130 400
Natural gas model, connect the manometer to the supply gas
pressure test port, see Figure 57 on page 51.
7. Connect one manometer (lower range) to the manifold gas
pressure tap at the outlet of the 24 VAC Gas Valve, see
Figure 56 on page 50 for location.
8. Open the Main gas Shutoff Valve.
9. Measure and record the supply gas pressure, this is a “static”
supply gas pressure reading; while the water heater is not
firing. Adjust supply gas pressure as necessary, see Supply
gas Pressure Adjustment on page 50.
lighting the water heater
1. Push in the gas control knob slightly and turn to the “on”
position, see Figure 56 on page 50.
2. Turn the water heater’s on/off switch to the “on” position.
3. Wait for the control system to complete its boot up sequence.
The Desktop screen showing the current Operating Set
Point and Tank Temperature will be displayed on the control
system’s LCD when the boot up sequence is complete.
4. using the control system menus and uIM (user interface
module), change the Operating Set Point to a setting higher
than the current tank temperature displayed on the control
system LCD plus the Differential setting to activate a call for
heating. See Control System Operation on page 41.
5. record the manifold gas pressure when the 24 VAC gas
Valve is energized and the Main burner is ignited, the
animated gas valve icon will be displayed on the Desktop
screen of the control system’s LCD when the control system
energizes the 24 VAC gas Valve, a animated flame icon will
appear when Main burner ignition is successful, see the
Status Icons descriptions in Table 10 on page 42.
start up