Siemens LMV5 Series Technical Instructions page 335

LMV Series
Direct Start (continued)
2. Program the LMV5 to utilize direct start through the following menu path:
Params & Display > BurnerControl > Configuration > ConfigGeneral >
NormDirectStart = DirectStart
3. Configure "Start/PS-Valve" (output terminal X4-03.3) to energize the 3-way solenoid
valve that diverts air pressure away from the blower air switch. This can be
programmed two different ways:
PS Relief – The solenoid valve is energized to divert air pressure away from the
blower air switch in phase 79.
PS Relief_inv – The solenoid valve is energized to expose the blower air switch to
air pressure in every phase except phase 79.
Program the "Start/PS-Valve" parameter through the following menu path:
Params & Display > BurnerControl > Configuration > ConfigIn/Output >
Start/PS-Valve
4. When using direct start, the postpurge time of the boiler is split into two stages:
PostpurgeT1Gas(Oil) – Defines the mandatory postpurge time (phase 74). If the
direct start option is selected and a call for heat exists, the LMV5 will postpurge
for this minimum amount of time.
PostpurgeT3Gas(Oil) – Defines the optional postpurge time (phase 78). If the
direct start option is selected and a call for heat exists, the LMV5 will skip this
postpurge time and go directly into prepurge after the functional test of the
blower air switch.
By minimizing the mandatory postpurge time, PostpurgeT1Gas(Oil), the full benefits of
direct start are achieved. Even with direct start enabled, the LMV5 retains a full
prepurge before opening the fuel valves and starting up. The optional postpurge time,
PostpurgeT3Gas(Oil), is the time required for the proper amount of air exchanges on a
normal shutdown. Both of these postpurge times can be set through the following
menu path:
Params & Display > BurnerControl > Times > Times Shutdown
SCC Inc. Page 5
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Technical Instructions
Document No. LV5-8000
Appendix A