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| Installation & Operation Manual |
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11 Operating information |
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Sequence of operation |
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| OPERATION |
| DISPLAY | |
1. Upon a call for heat, the control turns on the appropriate pumps | BLR: Standby | |||||
| (system and boiler pumps for space heating call; DHW pump | |||||
| for DHW call). | OUT: 123.8F(129) | ||||
2. The control | connects 120 VAC to the blower. The blower |
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| does not run at this time. | BLR: Standby | ||||
| • The manual reset high limit must be closed and reset. | |||||
| OUT: 123.8F(129) | |||||
| • Once the pumps are turned on, the flow switch must close. | |||||
• If the unit is equipped with gas pressure switches, they must | ||||||
| close. |
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| • If an auxiliary limit is connected to the unit, it must close. |
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| • The air pressure switch must be closed. |
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3. The control then starts a 15 second prepurge cycle. | BLR: PREPURGE | |||||
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| OUT: 123.9F(129) | |
4. Once the prepurge cycle is complete, and the blocked drain | BLR: IGNITION | |||||
| switch is closed, the control starts the 4 second trial for ignition | |||||
| by sending spark voltage to the spark electrode and opening | OUT: 123.9F(129) | ||||
| the gas valve. |
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5. If the control does not detect flame before the trial for ignition |
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| ends, the control will perform a 10 second postpurge. The 399 | BLR: POSTPURGE, PREPURGE | ||||
| model will start another prepurge and trial for ignition. If the | |||||
| burner does not light after 4 trials on the 399 model, the control | OUT: 123.9F(129) | ||||
| will lock out for one hour and then try again. |
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| If the burner does not light after 1 retry on Models 500 - 800 the |
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| control will lock out. |
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6. If the control detects a flame before the trial for ignition ends, it | BLR: SH 20% RATE | |||||
| begins to modulate the burner in order to maintain the set point. | |||||
| If the boiler lights due to a space heating call for heat, and the | OUT: 124.8F(129) | ||||
| ramp delay | function is active (default is off), the modulation |
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| will be held to a series of increasing limits afterthe burner has lit. |
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7. If the | space heating call for heat is active, and the DHW |
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| thermostat or sensor starts a DHW call for heat, the control will | BLR: DHW 85% RATE | ||||
| turn on the DHW pump, wait 2 seconds, and then turn off the | |||||
| boiler pump. | This will divert the hot water away from the | OUT: 177.8(180) | |||
| heating zone(s) and send it to the DHW tank instead. The |
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| control will then modulate to maintain the outlet temperature to |
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| the DHW boiler set point. |
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8. If the boiler is not part of a cascade, and the DHW call for heat |
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| remains active for more than 30 minutes, and the space heating |
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| call for heat is also active, then the control will turn on the boiler | BLR: SH 41% RATE | ||||
| pump, turn off the DHW pump after 2 seconds, and resume | |||||
| modulating based on the space heating set point. As long as | OUT: 123.0F(129) | ||||
| both the space heating and DHW calls for heat remain active, | |||||
| the control will switch back and forth between the two modes |
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| until one of them is satisfied. |
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9. Once both calls for heat are satisfied, the control will turn off the | BLR: POSTPURGE | |||||
| burner. | The blower will remain on for the 10 second postpurge | ||||
| cycle. | Any pumps that are running will continue to run for their | OUT: 127.4F(129) | |||
| respective pump delay times, then turn off. |
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10. | Boiler pump off, system pump continues its delay if longer. | BLR: Standby | ||||
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| OUT: 124.7F(129) | |
11. | System pump off. | BLR: Standby | ||||
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| OUT: 122.9F(129) | |
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