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PKG-PRC002-EN 71
Sequence of
Operation
Control Sequences of
Operation
Morning Warmup
This feature is available on all types of
factory-installed heat units and on units
with no heat. This function may still be
selected to support systems with heat
sources not provided by the self-
contained unit. At the conclusion of
unoccupied mode, the selected zone is
heated to the user-defined morning
warmup setpoint. The unit is then
released to occupied mode. There are
two types of morning warmup: full
capacity or cycling capacity.
• Full Capacity Morning Warmup (MWU)
Full capacity morning warmup uses full
heating capacity to heat the zone as
quickly as possible. Full heating capacity
is provided until the morning warmup
setpoint is met. At this point, the unit is
released to daytime mode.
• Cycling Capacity Morning Warmup
(MWU)
Cycling capacity morning warmup
provides gradual heating to overcome
“building sink” as the zone is heated.
Normal zone temperature control with
varying capacity is used to raise the zone
temperature to the MWU zone
temperature setpoint. Cycling capacity
MWU will operate until MWU setpoint is
reached or for 60 minutes. Then the unit
switches to occupied mode. Cooling will
suspend untill building load conditions
exceed the MWU setpoint of 3 F (1.7 C),
which is field adjustable.
Note: When using the morning warmup
option in a heating/cooling self-contained
unit in a VAV system, it is important to
maintain airflow through the unit. This
can be accomplished by electrically tying
the VAV boxes to the VAV drive max
output relay contacts on the unit’s RTM
module board or by using changeover
thermostats. Either of these methods will
assure adequate airflow through the unit
and satisfactory heating.
Ventilation Override (VOM) Option
The user can customize up to five
different override sequences for
purposes of ventilation override control. If
more than one VOM sequence is being
requested, the sequence with the highest
priority is initiated first. Priority schedule
is that sequence “A” (unit off) is first, with
sequence “E” (purge with duct pressure
control) last.
• UNIT OFF sequence “A”
When complete system shut down is
required, the following sequence can be
used.
•Supply fan – Off
•Supply fan VFD – Off (0 Hz)
(if equipped)
•Inlet guide vanes – closed
(if equipped)
•Outside air dampers – Closed
•Heat – all stages – Off, Modulating heat
output at 0 vdc
•Occupied/Unoccupied output –
Deenergized
•VO relay – Energized
•Exhaust fan (field-installed) - Off
•Exhaust damper (field-installed) - Closed
• PRESSURIZE sequence “B”
This override sequence can be used if a
positively pressured space is desired
instead of a negatively pressurized space.
•Supply fan – On
•Supply fan VFD – On (60 Hz)
(if equipped)
•Inlet guide vanes/VAV boxes – Open
(if equipped)
•Outside air dampers – Open
•Heat – all stages – Off, Modulating heat
output at 0 vdc
•Occupied/ Unoccupied output -
Energized
•VO relay - Energized
•Exhaust fan (field-installed) - Off
•Exhaust damper (field-installed) - Closed
• EXHAUST sequence “C”
With the building’s exhaust fans running
and the unit’s supply fan off, the
conditioned space becomes negatively
pressurized. This is desirable for clearing
the area of smoke when necessary; i.e.
from an extinguished fire, to keep smoke
out of areas that were not damaged.
•Supply fan – Off
•Supply fan VFD – Off (0 Hz)
(if equipped)
•Inlet guide vanes – Closed
(if equipped)
•Outside air dampers – Closed
•Heat – all stages – Off, Modulating heat
output at 0 vdc
•Occupied/Unoccupied output –
Deenergized
•VO relay – Energized
•Exhaust fan (field-installed) - On
•Exhaust damper (field-installed) - Open
• Purge sequence “D”
This sequence could be used for purging
the air out of a building before coming out
of unoccupied mode of operation on VAV
units. Also, it can be used to purge smoke
or stale air.
•Supply fan – On
•Supply fan VFD – On (60 Hz)
(if equipped)
•Inlet guide vanes/VAV boxes – Open
(if equipped)
•Outside air damper – Open
•Heat – all stages – Off, Modulating heat
output at 0 vdc
•Occupied/Unoccupied output – Energized
•VO relay – Energized
•Exhaust fan (field-installed) - On
•Exhaust damper (field-installed) - Open
• Purge with duct pressure control “E”
This sequence can be used when supply
air control is required for smoke control.
• Supply fan – On
•Supply fan VFD – On (if equipped)
•Inlet guide vanes – controlled by supply
air pressure control function with
supply air pressure high limit disabled
•Outside air dampers – Open
•Heat – all stages – Off, Modulating heat
output at 0 vdc
•Occupied/Unoccupied output – Energized
•VO relay – Energized
•Exhaust fan (field-installed) - On
•Exhaust damper (field-installed) - Open
Note: Each system (cooling, exhaust,
supply air, etc.) within the unit can be
redefined in the field for each of the five
sequences, if required. Also the
definitions of any or all of the five
sequences may be locked into the
software by simple key strokes at the
human interface panel.