Purge Proving; Introduction; Procedure - Siemens LMV5 Series Technical Instructions

Technical Instructions
Document No. LV5-8000

Purge Proving

Introduction

Purge proving verifies either a differential air pressure switch or an air damper end switch is in
the correct position before purge begins. This can be accomplished in two different ways:
• A differential pressure switch to verify proper air flow through the boiler. Once the
proper differential pressure is achieved, the prepurge position has been verified and the
purge begins.
• An end switch on the air damper. Once the air damper has moved to its fully open
position, the end switch closes and the purge begins.
The following procedure for purge proving on the LMV5 uses an additional two-pole relay with
either a differential pressure switch or an air damper end switch.
NOTE: Do not perform purge proving if using direct start on the LMV5!

Procedure

The following procedure uses either a differential pressure switch or an air damper end switch
for purge proving on the LMV5. For the rest of this procedure, either switch will be referred to
as a "proving switch".
1. Wire the LMV5, proving switch, and two-pole relay as shown below in Figure 12.
Appendix A
Figure 12: LMV5 Purge Proving Wiring Diagram
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