Model 399 - Lochinvar KNIGHT 399 Installation & Operation Manual

The Knight XL - How it works...
36. Air pressure switch
The air pressure switch detects blocked flue/inlet conditions.

Model 399

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Front View - Model 399
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Left Side (inside unit) - Model 399
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37. Pump relay board
The pump relay board is used to connect the boiler, system and
DHW pumps.
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Rear View - Model 399
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Right Side (inside unit) - Model 399
Installation & Operation Manual
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