Installation / Operation Instruction Manual

Page 110
10.C Shutting Down the Unit
Thisstepmustbeperformedbyaqualiedservice
person.
1. Turn o󰀨 the main electrical disconnect switch.
2. Close all manual gas valves.
3. If freezing is anticipated, drain the unit and be sure
to also protect the building piping from freezing. All
water must be removed from the heat exchanger or
damage from freezing may occur.
10.D Restarting the Unit
If the system has been drained, see 10.A for instructions
on proper lling and purging.
1. Turn o󰀨 the main electrical disconnect switch.
2. Close all manual gas valves.
3. Wait ve minutes.
4. Set the aquastat or thermostat to its lowest setting.
5. Open all manual gas valves.
6. Reset all safety switches (pressure switch, manual
reset high limit, etc.).
7. Set the temperature controller to the desired
temperature setting and switch on the electrical
power.
8. The unit will go through a prepurge period and
ignitor warm-up period, followed by ignition.
Table 25. Combustion Settings.
Model Gas Type High Fire CO
2
Low Fire CO
2
Pressure Di󰀨erential
1,600
Natural 9.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
Propane 10.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
2,000
Natural 9.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
Propane 10.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
2,500
Natural 9.0% ± 0.2 .25 lower than high re CO
2
0.9” to .09” wc
Propane 10.0% ± 0.2 .25 lower than high re CO
2
0.9” to .09” wc
3,000
Natural 9.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc
Propane 10.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc
3,500
Natural 9.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
Propane 10.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
4,000
Natural 9.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
Propane 10.0% ± 0.2 .25 lower than high re CO
2
0.5” to 1.2” wc*
*Only check the Pressure Di󰀨erential if there are problems getting the CO
2
in range.
10.E Sequence of Operation
Standby
Upon power-up, the boiler/heater enters Standby mode.
Upon a call for heat, the boiler/heater transitions into
Pre-purge Open.
10.E.1 Pre-purge Open
In Pre-purge Open mode, the blower is o󰀨 and the
boiler/heater conrms that since the blower is o󰀨, the
air proving switch (APS) is open. The gas valve and
spark are o󰀨. The duration of this mode is dened by
the Pre-Purge APS Max Open Time. If the APS is open,
the boiler/heater will transition to the Pre-purge Closed
mode. If the APS is closed, the boiler/heater transitions
to Lock-out mode. If the call for heat is removed, the
heater/boiler will transition to Standby mode.