Manual 2100-746D
Page
20 of 59
MC5000-B w/Enhanced Version Alarm Board
(Additional Outputs) plus MC5000-A Inputs/Outputs
Alarm relays can be wired for NO (close on alarm) or
NC (open on alarm) strategy. Alarm relays can be used
individually if there are enough available building
alarm points, or can be arranged into smaller groups
or even a single group so that all alarm capabilities
can be utilized. When multiple alarms are grouped
together and issued as a single alarm, there will be no
off-site indication of which specific problem may have
occurred, only that one of the alarms in the group has
been triggered. The individual alarm problem will be
displayed on the LED display on face of the controller.
Low Voltage Field Wiring
The MC5000 series controller is powered from the
HVAC units that it is controlling, 24 VAC (18-32V) low
voltage only (main I/O board).
Circuitry in the MC5000 isolates the power supplies of
the air conditioners so that no back feeds or phasing
problems can occur. Additionally, if one air conditioner
loses power, the MC5000 and the other air conditioners
are unaffected and will continue to operate normally.
Connect the low voltage field wiring from each unit
per the low voltage field wiring diagrams found in the
Connection Diagrams section beginning on page 43.
For low voltage wiring, an 18 gauge stranded copper
wire, color-coded cable is recommended.
NOTE:
A
minimum of 22-gauge control wiring should be used.
Controller Grounding
A reliable earth ground must be connected in addition
to any grounding from conduit. Grounding lugs are
supplied for this purpose and located inside at the
bottom of the panel (see Figure 3 on page 8).
Controller Power-Up
Whenever power is first applied to the controller, there
is approximately a 20-second time delay prior to any
function) becoming active. There is a 10-second delay
between all stages; even if the control is powered up
to a warm shelter and the temperature is above several
set points, there would still be a delay of 5 seconds
between each stage preventing excessive amp draw at
power-up.
Emergency Off
To disable the MC5000 series controller and shut down
all air conditioners/heat pumps, terminals marked
Emergency Off must be used. These terminals must
be jumpered together for normal operation. A normally
closed (NC) set of dry contacts may be connected
across the terminals and the factory jumper removed
for use with a field-installed fire suppression system.
The contacts will open if Emergency Off input is
detected.
Staging Delay Periods
The following delays are built in for both cooling and
heating:
Stage 1
0 seconds for blower (if not already on as continuous)
5 seconds for cooling or heating output
All Stages
The unit blower is called on with the first stage of any
unit unless “pre-purge” or continuous run is selected
in the System Setup options and the blower is already
running.
Blower Operation
The controller can be configured to have main HVAC
blowers cycle on and off on demand, have all blowers
run continuously, have the lead unit blower run
continuously or individual blowers can be selected
for continuous run by selecting the “Custom” option
in “System Setup” program and choosing the unit
numbers. Default setting is the blower(s) start and stop
on demand.
Pre-Purge
This feature allows the user to circulate the air in
the space to be conditioned to combat stratification
and allow for a more accurate measurement of space
conditions before activating the initial call for cooling
or heating. Circulation time will be selectable by user
(1 to 5 minutes in one minute increments). If selected,
pre-purge will be functional on initial call for cooling,
heating, dehumidification and humidification operation.
Pre-purge will run all available blowers for the user
selected time.
Pre-Purge Setup
Under the System Setup tab and on the Continuous
Blower menu, select Pre-purge; a pop-up screen will
provide instructions for the setup.
1. Option to Enable/Disable.
2. Selectable time option (1 to 5 minutes in one
minute increments).
Pre-Purge Sequence of Operation
When enabled, pre-purge will respond to a heating or
cooling call by running the blower of all configured
units for the time selected before staging on the
conditioning equipment. During this time, if either the
temperature moves more than 5° (heating or cooling) or
the humidity moves more than 5% (humidification or
dehumidification) beyond the respective set points, the
controller will exit pre-purge and stage units.
