Service Manual

1Service (continued)

Sequence of operation

Table 1A Sequence of operation - space heating and DHW

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

OUT: 123.8F(129)

for DHW call).

 

 

 

2. The control connects 120 VAC to the blower. The blower

 

does not run at this time.

BLR: Standby

• The manual reset high limit must be closed and reset.

• Once the pumps are turned on, the flow switch must close.

OUT: 123.8F(129)

• If the unit is equipped with gas pressure switches, they must

 

close.

 

• If an auxiliary limit is connected to the unit, it must close.

 

• The air pressure switch must be closed.

 

 

 

3. The control then starts a 15 second prepurge cycle.

BLR: PREPURGE

 

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.

 

 

 

5. If the control does not detect flame before the trial for ignition

 

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.

On the 500 - 800 models, the control will lock out indefinitely

 

after the first trial for ignition fails.

 

 

 

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

ramp delay function is active (default is off), the modulation

OUT: 124.8F(129)

will be held to a series of increasing limits after the burner has

 

lit.

 

 

 

7. If the space heating call for heat is active, and the DHW

 

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

 

control will then modulate to maintain the outlet temperature to

 

the DHW boiler set point.

 

 

 

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Lochinvar 399 - 800 service manual Sequence of operation, BLR Ignition

399 - 800 specifications

Lochinvar is known for its cutting-edge water heating and boiler systems, and the Lochinvar 399 - 800 series is no exception. Specifically designed for commercial applications, this series brings advanced technology and engineering to the forefront of hydronic heating solutions.

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