LEGEND
DPS — Differential Pressure Switch
ECR — Economizer Relay
HIR — Heating Interlock Relay
IFC — Evaporator (Indoor) Fan Contactor
IGV — Inlet Guide Vanes
MIR — Modulating Interlock Relay
MPE — Modulating Power Exhaust
NC — Normally Closed
NO — Normally Open
OMR — Occupied Mode Relay
PEC — Power Exhaust Contactor Coil
TB — Terminal Block
BUILDING PRESSURIZATION
Switch 2
Switch 3
Switch 6
Switch 7
Switch 8
Switch 9
SMOKE PURGE
Switch 2
Switch 4
Switch 6
Switch 7
Switch 8
Switch 10
Switch 1 and 1A — Field-supplied ON-OFF switch (timeclock) and
night thermostat (see Note 1).
Switch 2 — Firestat or smoke detector — normally closed.
Switch 3 — Building pressurization switch (energize indoor
fan motor) — normally open.
Switch 4 — Smoke purge switch (energize power exhaust
motor) — normally open.
Switch 6 — Switch to drive economizer outdoor-air damper
fully open — normally open.
Switch 7 — Switch to isolate evaporator-fan motor from
power exhaust motor — normally closed.
Switch 8 — Switch to provide 24-v power to inlet guide vane
motor and modulating power exhaust damper
motor — normally open.
Switch 9 — Switch to drive inlet guide vanes fully open —
normally open.
Switch 10 — Switch to drive modulating power exhaust
dampers fully open — normally open.
NOTES:
1. Switches 1 and 1A are for timeclock and night thermostat and are
not part of building pressurization or smoke purge.
2. Power exhaust option available
only
on 48/50NP units.
3. is field wiring.
4. is factory wiring.
5. All switches are field supplied.
6. For building pressurization, field-supplied power source must drive
room terminals wide open.
7. Install field-supplied dry contacts between TB2 terminals 8 and 9
and at TB2 terminal 15 to drive open room terminals when HIR1
contacts are energized.
Fig. 25 — Field Wiring for Building Pressurization and Smoke Purge
18
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