EngA C-TRAC2

A C-TRAC2.1 MANUAL
IOM-12 Page 1 March 1999 R1
A
C-TRAC2.1
COOLING, ECONOMIZER, HEAT RAMP CONTROL
If any errors or omissions are noted please contact Wade Pascoe at (403) 287-4775 or Fax (403) 287-
4799 or (403) 243-5059.
Any reference to C-TRAC or to C-TRAC2 in the following text applies to Model C-TRAC2.1. The Model 2.1 is
similar to previous versions with the following changes:
 “HD” terminal added (0-10 VDC heat output)
 “ED” terminal added (0-10 VDC economizer output)
 Removal of pot 6
I. APPLICATION
The C-TRAC is designed to control cooling and economizer functions on Engineered Air cooling units. It also
includes a heat output control signal.
II. SERVICE
To ensure warranty is honoured, only a qualified HVAC service person, who has received training on the C-
TRAC2.1, should be employed for service and troubleshooting. If information is required please contact the
nearest Engineered Air Office.
III. GENERAL
The C-TRAC2.1 is a discharge air temperature control that includes the option of connecting a reset control of
some type to electronically modify the discharge temperature set point.
The C-TRAC2.1 is a general purpose, multi-function controller. The C-TRAC2.1 performs the following
functions:
 Modulating heat output 8.5 VDC (from HT (+) and B () terminals)
 Modulating heat output 10 VDC (from HD (+) and B () terminals)
 Modulating economizer output (from R, B, W terminals) for 3 wire signal to series 90 damper actuators
 Modulating economizer output 10 VDC (from ED (+) and B () terminals) – 2 wire signal
 Switching for 5 stages of mechanical cooling
The C-TRAC2.1 always starts in heat mode. If cooling is required it switches to economizer to satisfy
demand. If this is not adequate to satisfy demand, it switches to mechanical cooling.
The heating output supplies a DC voltage signal to operate the Engineered Air heating controllers. (G-TRAC,
G-TRAC2, DJM2, DJT-2, H-TRAC, 109 interface, 3 way mixing valves for hot water or steam heating.)
The economizer has four choices of control thereby giving maximum operational flexibility.
The mechanical cooling switching has minimum run time, minimum off time, and inter-stage timing.
Each time the C-TRAC2.1 is first powered on the H and N terminals it begins its cycle in the heat mode. How
quickly the C-TRAC2.1 will react, depends on how far the temperature at the discharge sensor is from the
calculated set point. If the call is for cooling the C-TRAC2.1 will go to the economizer operation and try to
satisfy the cooling demand. If that is not possible then the C-TRAC2.1 will bring on the mechanical cooling if
the outdoor ambient is warm enough. This process could take as much as 20 minutes to switch from the
heating mode through the economizer mode to the mechanical cooling mode.