LAARS Mighty Therm IW (Sizes 500-1825) - Installation, Operation and Maintenance Instructions - Manual (Page 20)

LAARS Heating Systems
Page 20
Lower the front of the burner (to avoid damaging
pilot shield) then remove the burner tray.
Caution
Black carbon or green soot on a dirty heat
exchanger can, under certain conditions, be
ignited by a random spark or open flame. To
prevent this unlikely occurrence, dampen the
soot deposits with wet brush or fine water
spray before servicing or cleaning the heat
exchanger.
With a wire brush, remove soot and loose scale
from heat exchanger. Clean fallen debris from
bottom of heater. Make sure burner ports are
clear and pilot assembly is free of debris.
d.
Reassemble in reverse order:
Be sure the heat exchanger baffles are replaced.
8. The gas and electric controls installed on heaters
are engineered for both dependable operation
and long life, but the safety of this equipment
completely depends on their proper functioning.
It is strongly recommended that the basic items
be checked by a competent serviceman every
year and replaced when necessary. The basic
controls are:
a.
Water temperature controls.
b. Pilot safety system.
c. Automatic electric gas valve(s).
d. Flow sensing safety device.
9. Low water cutoffs should be inspected every six
(6) months, including flushing of float types.
NOTE: Warranty does not cover any damage
caused by lack of required maintenance or improper
operating practices.
10.
Both modulating and stage valve are adjusted at
the factory for minimum permissible rates and
should not be readjusted.
SECTION 5.
Troubleshooting and Analysis of
Service Problems
1. For proper service and problem diagnosis of the
heater and heater system, the following tools are
required:
a.
Gas pressure test kit with range from zero
to 14 W.C. Either a slack tub manometer or
an accurate gas pressure gauge is
acceptable with proper adapters which will
connect to the available fittings in the line
and on the gas valve.
b. Multi-meter with the following ranges:
0 to 500 volts A.C.
0 to 1000 ohms continuity.
c. Tube cleaning kit consisting of reamer,
stainless steel brush, speed handle and
handle extensions.
d. Heater thermometer (with 1/2" NPT well)
100-240°F.
2. In addition, the heater should be equipped with a
system pressure gauge with proper ranges for
heater operation.
I. HEATER WILL NOT FIRE.
Possible Cause What To Do
A. Electric power is off A. Check to see that main power
switch is “ON.” Use testing
device to trace power to
heater junction box.
B. Operating or safety control B. Turn off power. Use continuity
has opened circuit to electric across terminals of each
gas valve. operating and safety control
switch up to the electric gas
valve. Replace effective
control.
C. Pilot flame is out. C. Relight pilot per instruction.
D. Manual reset device has D. Follow instructions for start-
tripped. up. Reset Pilot safety and all
manual reset safety switches
and reset manual safety gas
valve.
E. No gas pressure to burners. E. Trace gas line to service
shutoff cock. If service cock is
open, trace gas line to meter.
If no pressure is present at
meter, call for public utility
service. If gas is present in
heater inlet, check pressures
in following sequence:
(1) downstream from pressure
regulator. (2) downstream
from electric gas valve.
Replace or adjust as
necessary.
F. Electric gas valve operator is F. Disconnect wiring harness at
burned out or shortened. gas valve terminals. Check
continuity to actuator coil. If
open circuit or short is
indicated, replace coil or
operator.