Sequence Of Operation - Modine Manufacturing SSD Installation And Service Manual

SEQUENCE OF OPERATION

SEQUENCE OF OPERATION
DIGIT 8=E: ELECTRO-MECHANICAL CONTROLS
A 24V signal from the thermostat to terminal G supplies power
the blower motor(s), condensate pump and vane motor (if
equipped). A toggle switch on the control box can be used to
switch the oscillating vanes on or off. The condensate pump
will run continuously during cooling operation, as long as there
is a call for cooling. A call for heating, at terminal W, or cooling,
at terminal Y, will energize the water valve actuator and allow
water to flow through the cassette coil. When the call for heating
or cooling is satisfied the valve will close.
If the temperature drops below the set-point of the coil freeze
stat (Model Digit 11=F), the water valve with automatically open
to circulate water through the coil.
If the condensate float switch detects a high level of water in the
condensate tray, the switch will open, activate the condensate
pump and disable the heating/cooling signal until the water level
drops down to normal.
Note:


DX or Heat Pump units (Model Digit 3=D or H)
with electro-mechanical controls, a thermostat with
compressor on/off minimum time protection is required.
DIGIT 8 = M: MICRO-PROCESSOR CONTROLS
Indoor Fan Operation
The indoor fan will run continuously at the most recently set
speed or will alter the speed according to the room temperature
conditions when set to Auto. The indoor fan will continue to
run until the unit is turned off by the user or via a pre-set time
setting. When the unit is turned off during heating, the indoor
fan will continue to run for approximately two minutes, this helps
to dissipate residual heat from the electric heaters. In SLEEP
mode the fan will cycle with a call for heating or cooling.
Temperature Control
The microprocessor controller references the factory mounted
return air sensor and compares it to the temperature setpoint to
determine when cooling or heating is required. The dead band is
programmed to 4ºF (2.2°C). Under normal operation, cooling or
heating will be activated at the limits of the dead band and will
continue to operate until setpoint is achieved. The temperature
setpoint can be adjusted between 58°F and 90ºF (14.4°C
and 32.2°C) in 2ºF (1.1°C) increments by using the infrared
transmitter or digital wall stat accessory.
Power Failure
The controller will auto restart in its previous mode of operation
after a power failure. When power is restored the controller will
revert to its last operating mode, e.g. if the controller was turned
on before power fail, after power is restored the controller will
automatically turn on. Alternatively if the controller was turned
off before power fail, after power is restored the controller will
remain off.
Alarms
• Return Air Sensor Failure
• Condensate High Level
• Indoor Coil Under Temperature (If freeze stat is on
unit – Model Digit 11=F)
16
Setting Jumper Links
Jumper Links are located on the Microprocessor Controller PCB
to offer different control features and their functionality is listed
below in Table 16.1.
Table 16.1 - Jumper Links
Jumper
Links
In heat or cool modes, fan
JMP1
operates in auto mode
"4-Pipe" Configuration
Cool output connected to
JMP2
cooling device. Heat output
connected to heating device.
JMP3
N/A
Jumper link settings must be made with the power turned off.
Jumper link 1 will be factory set to SHORT. Jumper link 2 will be
factory set to suit the type of unit. Jumper link 3 will be factory
set to OPEN.
Remote Infrared Transmitter
The infrared transmitter is used to switch the unit on/off, change
temperature settings, fan speed, operating mode, to toggle
the motorized air sweep (where fitted), and has a built in timer
function. See page 18 and page 19 for more details on the
infrared transmitter.
8-504.11
Short Open
In cool mode, fan runs
continuously. In heat mode fan
runs on demand.
"2-Pipe" Configuration Cooling
and heating signals sent from
cool output
N/A