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7. START-UP PROCEDURES
The water, gas and electrical systems of the heater
should be completed and checked as described in the
heater installation manual and associated documents.
Sequence of Operation - IID Ignition
On a call-for-heat, the Power Vent (and heater pump)
start. When the draft-proving switch and the flow switch
circuits close, the ignition system, consisting of an
electronic spark module, pilot gas system and flame
sensor, are energized.
When all safety circuits are proven, the automatic main
gas valves will open and the heater will operate.
When the operating temperature control circuit is
satisfied, the heater will shut down and the fan will
operate for the post-purge period selected on the fan
post-purge board (10-60 sec).
1. Turn on power to the heater with the manual main
gas valve and pilot gas valve off.
2. Check power connections.
3. Close heater power switch.
4. Set operating control to call-for-heat.
a. Fan motor starts and draft proving switch
closes.
b. Heater pump starts and flow switch closes.
c. Ignition module is energized.
d. Check for spark at gas pilot.
5. Turn operating control to end call-for-heat.
6. Wait a minimum of 60 seconds.
7. Open pilot gas valve.
a.
Repeat step 4.
8. After pilot gas is proven and main safety shutoff
valve is energized, slowly open manual main gas
shutoff valves and the main burners will ignite.
9. Heater will operate until call-for-heat is satisfied.
10. Check draft at point A (See Figure 7).
a. Draft should be -0.005 to -0.01 in. WC at full
fire.
b. Adjust barometric draft control until this reading
is obtained.
11. Restart heater and visually check all components
for proper operation.
12. Check all vent connections and joints for leakage.
Correct if found.
13. To restart heater after a failure, follow the
procedures outlined above and other subsequent
or related sections outlined in the heater manual.
NOTE: Verify shaft rotation is CW when viewed from
motor end.
Emergency Shutdown—Shut off all power and gas,
call gas utility.
8. CONTROLS
Blower Motor Contactor
& Purge Relay
The solid-state control starts the blower motor and keeps
it running for up to one minute after the call-for-heat is
satisfied. This post-purge period clears the combustion
area of any residual gas buildup.
Figure 28. Solid State Fan Delay Board
Draft-Proving Switch
The draft-proving switch ensures that the blower is
operating. The switch is in the limit circuit and does not
allow the ignition module to operate unless it is closed.
NEGATIVE PRESSURE
CONNECTOR
NORMALLY
OPEN
TERMINAL
Figure 29. Draft Proving Switch
ADJUSTING
SCREW
COMMON TERMINAL
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