MicroMetl ECD-SRT SA Series - Checkout and Troubleshooting

11
Fig. 20 - Meter Location for Checkout and
Troubleshooting
M20612
N1
P1
T1
N
2V
2V
2V
B
A
SR
SO
AQ
C
D
Free
Cool
10V
EXH
DCV
EXH
Set
10V
DCV
Max
10V
DCV
Set
Min
Pos
Open
P
T
AQ1
SO+
SR+
1
2
DC VOLTMETER
620 OHM RESISTOR
W7212
+
S
+
C7400
1
2
INSERT DC VOLTMETER BETWEEN AQ AND AQ1 FOR
CHECKOUT AND TROUBLESHOOTING.
JUMPER USED FOR SINGLE ENTHALPY CONTROL.
Checkout Procedure
Step
Proper Response
1. CHECKOUT PREPARATION FOR ECONOMIZING ONLY
All LED are off; Exhaust Fan contacts are open.
Disconnect power at TR and TR1.
Disconnect devices at P and P1.
Jumper P to P1 (defaults to on board MIN POS potentiometer).
Place 5.6K ohm resistor across T and T1 (Blue sleeve- provides input to
economizer that the MAT is between 50-55F)
Jumper TR to 1 (call for cooling from the thermostat).
W7212 only jumper TR to N (places economizer in occupied mode).
.
If connected, remove C7400 Enthalpy Sensor from terminals S
O
and +.
Connect 1.2K ohm, from 4074EJM Checkout Resistor kit, (purple sleeve)
across terminals S
O
and + (makes OA enthalpy high).
Place 620 ohm resistor (white sleeve) across S
R
and +
(makes return enthalpy lower than OA).
Set MIN POS and DCV MAX potentiometers fully CCW.
Turn DCV setpoint potentiometer mid position
(this sets the DCV ventilation at approximately 1000 ppm).
Turn exhaust potentiometer to mid position (motor will be
apporximately 50% open when the exhaust fan contacts make).
Set enthalpy potentiometer to D.
Apply power (24 Vac) to terminals TR and TR1.
Table 7. Checkout for Economizer
CHECKOUT AND
TROUBLESHOOTING
Checkout requires a 9V battery, 620 ohm, 1.2K ohm,
5.6K ohm, and 6.8K ohm resistors. Use table 7 and Fig. 20 for
checkout.
!
CAUTION
Equipment Damage Hazard.
Excessive force can damage potentiometer
controls.
Use a small screwdriver when adjusting enthalpy
changeover and minimum damper position controls