L.B. White COMBO-MCS - Manual (Page 19)

READ THIS ENTIRE SECTION BEFORE
BEGINNING TO TROUBLESHOOT PROBLEMS.
The troubleshooting flow charts on the following pages
provide systematic procedures for isolating problems. The
char ts are intended for use by a QUALIFIED SERVICE
PERSON. D
DO NOT SER VIC E UNLESS Y OU HAV E BEEN
PROPERLY TRAINED.
Components should be replaced only after each step has
been completed.
Use the green LED on the programmable controller for
assistance in troubleshooting if problems occur. A blink
pattern of 1 second ON, 1 second OFF indicates normal
operation.
The troubleshooting flow charts pertain to forced air, and
radiant heaters, (spark and manual ignition). Unless
otherwise noted, the troubleshooting is the same for all
heaters, regardless if forced air or radiant.
TEST EQUIPMENT REQUIRED
• Digital Multimeter - for measuring AC and DC voltage and
resistance.
INITIAL PREPARATION
■
Check all internal wiring for loose connections and
worn/damaged insulation.
Problems Page
Green LED on controller is steady ON . . . . . . . . . . . . . .20
Green LED on controller is OFF. No display at touch
pad, indicator lights are out, heaters do not operate . .20
Green LED on controller is blinking 0.5 seconds ON,
0.5 seconds OFF. Red sensor failure light is on . . . . .21
Forced air or spark ignition heaters do not start, but
zone light is ON. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Zone 1 forced air or Zone 2 radiant heaters do not
start. Zone 1 or 2 LED os OFF, but touch pad is
functional . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Heaters start and operate properly, but zone
LED is off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Heaters in zone start, but heat output does not
change is response to SmartBox
™
setting . . . . . . . . . .22
SmartBox
™
Zone 1 (forced air) does not operate
concurrently with room controller . . . . . . . . . . . . . . . .22
Sequence of Operation
a. 120 VAC is supplied to SmartBox™.
b. Call for heat occurs from building controller.
c. Building controller closes heating contacts
enabling SmartBox™ operation for forced air heater
operation.
d. 120 VAC is sent to both transformers and to both
relays.
e. Upper transformer reduces 120 VAC to 24 VAC which
is sent to the programmable controller and radiant
heat signal conditioner.
-- Green LED on blinks 1 second ON, 1 second
Off (Normal operation)
f. Lower transformer reduces the 120 VAC to 24VAC
and sends it to the forced air signal conditioners.
g. Programmable controller sends 24 VAC to both
relays.
-- 24 VAC is used to close the relay coil.
-- Relays send out 120 VAC for power supply to
heaters.
-- Forced air or spark ig gnition radiant
heaters only
-- Heaters start the ignition cycle
h. Programmable controller sends out 4-20 mA signal to
the signal conditioners.
i. Signal conditioners use the 4-20 mA signal to change
the received 24VAC into 0-15 VDC output (forced air)
and 0-24 VDC (radiant).
-- Forced air signal conditioner sends the 0-15
VDC to the forced air heater’s variable rate
gas control
-- Radiant signal conditioner sends the 0-24
VDC to the proportional solenoid valve.
j. Ignition of gas occurs at a specific rate.
-- Room warms to desired temperature.
k. Building controller and SmartBox™ work
simultaneously to monitor temperature until heat
demand is satisfied.
Troubleshooting Instructions
WARNING
Electrical Shock Hazard
■
Troubleshooting this system may require operating the
unit with line voltage present. Use extreme caution
when working on the
SmartBox™.
■
Failure to follow this warning may result in personal
injury or death.
19