A
base
IOM67
9
February 2021 R0
RPM
AI
VFD Feedback Speed
W+/- AI
Modulating heating thermostat
AA1,2 AI
Ambient / Outside temperature
DA1,2 AI
Discharge temperature
Y+-
AI
Modulating cooling thermostat
HiE
DI
High Speed Enable
ENC
DI
Enable Cooling
OCC
DI
Occupied / unoccupied mode
EnF
DI
Enable Fan
DES
DI
Damper end switch
FbB
DI
Air proving switch
BYP
DI
VFD Bypass
MX1,2 AO
Maxitrol Modulating Valve
Humidifier Version Terminals
FV
DO
Fill Valve
MV
DO
Mixing Valve
DV
DO
Drain Valve
FVS
DO
Second Fill Valve
LWP
CI
Low Water Probe
FWP
CI
Full Water Probe
DN1,2 AI
Drain Water Temperature
CD-XM Terminals
H N
24Vac Power Supply
GND
Ground
LmA,B
Internal Modbus
OS
AI
Tach
YS
AI
Tachometer -
GS
AI
Tachometer reference
CB
AO
TRIAC output
120
120Vac input
SR1,2 DO
Safety relay
APPLIANCE TYPES
DJ STYLE INDIRECT FIRED
For indirect fired equipment with DJ (E, S, X) style
burners up to size 140.
On a call for heating the combustion blower will be
enabled to full speed to prepurge the heat
exchanger. Once the prepurge time has elapsed
the combustion blower speed will reduce to ignition
speed and then enable the ignition control to start
and prove pilot flame, then open the main safety
valve (SSOV). After a time delay the pilot valve IS
disabled. The burner is allowed to operate from
low fire to high fire at a 15:1 turndown ratio to
maintain the requested discharge air temperature
by modulating the control valve and the
combustion blower speed. If heating is not
required the burner will be disabled and the
combustion blower will enter a post purge time,
and then shut down.
The
base
can control either a Maxitrol magnetic
style modulating valve or an actuator and ball valve
combination.
Combustion air blower modulation is controlled by
either the CD-XM expansion module. If using an
electronically commutated motor (ECM) modulation
is directly controlled from the
base
.
DG STYLE INDIRECT FIRED
For indirect fired equipment, DJX sizes 200 and
300, and all DG sizes. These use actuator
controlled air flow control damper and gas ball
valves.
On a call for heating the combustion blower will be
enabled and the air actuator will open to the
prepurge setpoint to purge the heat exchanger.
Once the prepurge time has elapsed the gas and air
actuators will move to ignition position and then
enable the ignition control to start and prove pilot
flame, then open the main safety valve (SSOV).
Once the pilot flame has proven and the main
flame is established, the
base
will then disable the
pilot valve. The burner is allowed to operate from
