Troubleshooting Guide - L.B. White Therma Grow HW120 Owner's Manual And Instructions

22
Therma Grow™ Greenhouse Heaters

Troubleshooting Guide

READ THIS ENTIRE SECTION
BEFORE BEGINNING TO
TROUBLESHOOT PROBLEMS.
WARNING
Electrical Shock and Burn Hazard
n This heater can start at any time.
n Troubleshooting this system may require
operating the unit with line voltage present and
gas on. Use extreme caution when working on
the heater.
n Failure to follow this warning may result in
personal injury or death.
The following troubleshooting guide provides sys-
tematic 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
n Visually inspect equipment for apparent damage.
n Check all wiring for loose connections and worn
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, to 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. For PLUS models, 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.
Owner's Manual • Therma Grow™
Heating Mode Problems
L.E.D. light is not on during a call for heat ...... 24
L.E.D. diagnostic light is flashing:
A. Rapid flash ............................................. 25
B. Long flash
(2 seconds on-2 seconds off) .......
C. One time................................................. 25
D. Two times ............................................... 26
E. Three times ............................................ 27
F. Four times ............................................... 28
G.Five times................................................ 28
H.Six times.................................................. 28
PLUS MODEL
Ventilation Mode Problems
A. Motor Does Not Run .................................. 28
B. Motor Hums, Does Not Run ....................... 28
OPERATION SEQUENCE:
-- Line voltage is sent to selector switch.
-- Selector switch is positioned to HEAT.
-- Line voltage is sent to motor relay and 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 contacts close on call for heat 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 relay.
-- Motor relay closes.
-- Line voltage is sent 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 is returned back to control.
-- Ignition control sends 24 volts from terminal GV to high
limit switch.
-- If limit switch contacts are closed, limit sends 24 volts
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