Installation and Maintenance Manual
ECM Overview and Setup
66 UNT-SVX07D-EN
The ECM engine board provides additional temperature
controlled logic to help coordinate certain electric-heat
and valve logic functions:
• On units with electric heat and a changeover coil, the
engine board and adapter boards are pre-configured
to cause hydronic heat and electric heat to be mutually
exclusive:
– On units with ComfortLink™ controls (Tracer ZN
controller
s), the Tracer ZN board will serve as the
primary logic to select the electric heat only if hot
water is not available, but the engine board will
service as a backup lockout.
– On units with Customer Supplied Controllers (CSTI
units), the engine board and CSTI board will serve
as the primary lockout.
• On CSTI units selected with a c
hangeover coil
configuration, the engine board is factory configured
to work in conjunction with the CSTI adapter board to
provide a useful auto-changeover function.
Traditionally, a fixed setpoint bi-metallic disc
temperature switch is used to provide changeover with
customer controls; however, the engine board has
defeatable and configurable bi-metallic disc
temperature switch emulation when combined with
the CSTI adapter board. The ECM engine is
preconfigured for typical values, so changeover
settings do not necessarily need to be changed.
– An NTC thermistor is suppl
ied and affixed to the
supply pipes where applicable. The ECM engine
has several settings that affect the operation of the
changeover function:
•
parameter should normally be set to
or to use the changeover functions.
•
parameter should be chosen if the unit has
a changeover coil without electric heat.
•
parameter should be chosen if the unit
has a changeover coil with electric heat.
Generally, this will perform the same as the
parameter but in addition, will disable heating
function on electric heat and on the changeover
coil if there are fan failures. The auxillary heating
coil function will continue to operate and
respond to the customer heating request.
•
parameter should be set to for CSTI units and
to for ComfortLink controller units.
•
parameter defines the temperature at which the
engine board will close the triac onboard the ECM
engine (if
parameter is set correctly).
•
parameter defines the temperature at which the
engine board will open the triac onboard the ECM
Engine (if
parameter is set correctly). By leaving
a “gap” between the make and break value, we will
simulate hysteresis of a real bi-metallic disc
temperature switch.
• When combined with the CST
I adapter board, the bi-
metallic disc temperature switch emulation and the
electric heat lockout function will work when the
switches are set correctly.
Adjustment and Configuration of the CSTI
Adapter Board
For CSTI units, the board mounted switches have to be set
appropriately to enable the desired functionality.
Notes:
• All switches are factory-set based on customer
configuration of the unit model number. The unit will
function correctly as shipped; however, the switch
functions and positions are depicted for customer
convenience and for service and troubleshooting aids.
• SW3 and SW4 work in conjunction with settings on the
ECM engine controller. Simple activation of
CAUTION
Burn Hazard!
If SW4 is turned off, the factory/customer controller/
thermostat will be able to actuate the electric heat
while hot water is available or if the fans have failed.
This switch should NOT be turned off if the unit
schematic indicates that it should be on, to prevent
overheating of the unit (due to simultaneous electric
heat and hydronic heat actuation, or failure of the fan)
and to use the preferred hydronic heating over electric
heat. Failure to follow this instruction could result in
the unit overheating and becoming hot to the touch,
which could result in minor or moderate injury, and/or
equipment damage.
Figure 30. CSTI adapter board: board-mounted
switches
Table 17. CSTI adapter board: switch functions
Switch
(L-R) SW1 SW2 SW3 SW4
Function Valve one
operation
logic
Valve two
operation
logic
Changeover
Function
Electric Heat /
Fan Proving
Function
UP position
(towards
terminal
strip)
Normally
Open Valve
Normally
Open Valve
Changeover
Function ON
Electric Heat /
Fan Proving
Function
DOWN
position
(towards
black relays)
Normally
Closed Valve
Normally
Closed Valve
Changeover
Function OFF
Electric Heat /
Fan Proving
Function
UNT-SVX07_-EN.book Page 66 Friday, April 27, 2012 9:40 AM