L.B. White HW120 Plus Therma Grow - Manual (Page 20)

Troubleshooting Instructions
READ THIS ENTIRE SECTION BEFORE BEGINNING TO
TROUBLESHOOT PROBLEMS.
The following troubleshooting guide provides systematic
procedures for isolating equipment problems. This guide is
intended for use by a QUALIFIED GAS HEATER SERVICE
PERSON. DO NOT ATTEMPT TO SERVICE THESE HEATERS
UNLESS YOU HAVE BEEN PROPERLY TRAINED.
TEST EQUIPMENT REQUIRED
The following pieces of test equipment will be required to
troubleshoot this system with minimal time and effort.
• Digital Multimeter - for measuring voltage and resistance.
• Low Pressure Gauge - for checking inlet and outlet
pressures at the gas control valve against dataplate rating.
INITIAL PREPARATION
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Visually inspect equipment for apparent damage.
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C h e c k a l l w i r i n g fo r l o o s e c o n n e c t i o n s a n d wo r n
insulation.
The ignition control module is self-diagnostic. The red light
located on the control will flash a specific pattern depending
upon the problem which is diagnosed. To use the flow charts, t
identify the problem by the light pattern of the L.E.D. (light
emitting code) diagnostic light. If the light is flashing, the flash
pattern will be followed by a pause and then a repeat of the
flash pattern until the problem is corrected. The light will only
be on when the selector switch is positioned to HEAT and the
thermostat or controller is calling for heat. The light will not be
on when the selector switch is positioned to VENT.
Heating Mode Problems Page
L.E.D. light is not on during a call for heat. . . . . . . . . . . . . . . 21
L.E.D. diagnostic light is flashing:
A. Rapid flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
B. Long flash ( 2 seconds on-2 seconds off) . . . 22
C. One time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
D. Two times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
E. Three times . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
F. Four times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
G.Five times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
H.Six times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Ventilation Mode Problems Page
A. Motor Does Not Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
B. Motor Hums, Does Not Run . . . . . . . . . . . . . . . . . . . . . . . 25
OP PERATION SEQUENCE:
-- Line voltage is sent to selector switch.
-- Selector switch is positioned to HEAT.
-- Line voltage is sent to transformer
-- Terminal at transformer branches off line voltage to . .
terminal L1 on ignition control.
-- Transformer reduces line voltage to 24 VAC.
-- 24 VAC is sent to thermostat.
-- Thermostat closes and returns 24 volts to terminal W on
ignition control.
-- Red light on ignition control is illuminated.
-- Ignition control sends flame sense current to flame sensor.
--
Ignition control module performs self safety check.
-- Internal components are tested.
-- Air proving circuit is tested
-- Control sends 24 VAC from terminal PSI to air . . .
proving switch.
-- Ignition control module begins ignition trial sequence.
-- Ignition control sends 115 volts from terminal IND to motor.
-- Motor starts.
-- Air proving switch closes and 24 volts are returned to
terminal PSO of ignition control.
-- Motor stops.
-- Ignition control module sends 115 volts to hot surface igniter.
-- Igniter reaches ignition temperature in 17 seconds.
-- Ignition control restarts the fan motor while sending 24 VAC
to air proving switch.
-- Switch closes and 24 volts returned back to control.
-- Ignition control send 24 volts from terminal GV to high limit
switch.
-- If limit switch contacts are closed, limit sends 24 volts
to gas control valve
-- Gas control valve opens
-- Ignition occurs.
-- Flame sense current is passed through burner flame back to
ignition control.
-- Igniter stays powered until ignition control proves flame sense
-- Igniter then shuts down.
-- Gas control valve stays open
-- Gas control valve cycles from first to second stage heat
based on thermostat setting
-- Room warms to desired temperature.
-- Thermostat is satisfied.
-- Heater shuts down.
-- Process starts again on a call for heat.
IGNITIO ON T TRIAL SEQUENCE:
-- First trial for ignition takes approximately 30 seconds
-- Two more ignition trials occur
-- Second trial immediatley follows if first trial failed.
-- If second trial fails
-- Ignition control starts a 15 minute waiting period
-- Allows the ignition interruption to pass
-- At end of 15 minutes
-- Ignition control attempts third and final ignition trial
-- If igntion control does not prove burner flame after third
trial, the control goes into safety lockout ( 3 flash)
-- Gas valve closes.
-- Hot surface igniter shuts down
-- Fan motor stops.
-- To retry for ignition, turn the heater off and then on.
WARNING
■
This heater can start at any time.
■
Troubleshooting this system may require operating the
unit with line voltage present and gas on. Use extreme
caution when working on the heater.
■
Failure to follow this warning may result in personal
injury or death.
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