Lochinvar Knight 80 - 285, Руководство по обслуживанию

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1
Service
Service Manual
11
1
Service
(continued)
Sequence of operation
Table 1 Sequence of operation - space heating and DHW
OPERATION DISPLAY
1. Upon a call for heat, the control turns on the appropriate pumps
(system and boiler pumps for space heating call; DHW pump
for DHW call).
BLR: Standby
OUT: 123.8F(129)
2. The control connects 120 vac to the blower. The blower does
not run at this time.
• If the unit is equipped with a flow switch or low water cutoff, it
must close before the control powers up the blower.
• If the unit is equipped with a manual reset high limit it must be
closed before the control powers up the blower.
• If the unit is equipped with a solenoid valve and/or a vent
valve, they will be energized along with the blower.
• If the unit is equipped with a gas pressure switch, it must close
at this time.
• If there is an auxiliary device connected to the unit, the unit
will then provide 24 vac to its enable relay. If the auxiliary
device has a proving switch, it must close before the
sequence continues.
BLR: Standby
OUT: 123.8F(129)
3. The control then starts a 10 second prepurge cycle.
BLR: PREPURGE
OUT: 123.9F(129)
4. Once the prepurge cycle is complete, and the blocked drain
switch and auto-reset high limit are closed, the control starts
the 5 second trial for ignition by sending spark voltage to the
spark electrode and opening the gas valve.
BLR: IGNITION
OUT: 123.9F(129)
5. If the control does not detect flame by the end of the trial for
ignition, the control performs a 10 second postpurge, another
prepurge and tries to light the burner again. If the burner does
not light after 4 trials, the control locks out for 1 hour and then
tries another set of 4 trials.
BLR: POSTPURGE, PREPURGE
OUT: 123.9F(129)
6. If the control detects a flame before the trial for ignition ends, it
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
ramp delay function is active (default is off), the modulation
will be held to a series of increasing limits after the burner has
lit.
BLR: SH 20% RATE
OUT: 124.8F(129)
7. If the space heating call for heat is active, and the DHW
thermostat closes, the control will turn on the DHW pump, wait
2 seconds, and then turn off the boiler pump. This will divert
the hot water away from the heating zone(s) and send it to the
DHW tank instead. The control will then modulate to maintain
the outlet temperature to the DHW boiler set point.
BLR: DHW 85% RATE
OUT: 177.8(180)