Table of Contents
Advertisement
Page 36
Legacy
If the main burners will not light after follow-
ing the lighting instructions in Section 7.3, check the
voltage reading between the PP terminal on the gas
valve (test point 1) and the TH terminal on the gas
valve (test point 17). If the meter shows less than
220mVDC then there is a problem with the pilot
generator, the sensors in the safety loop or the control
panel. Follow the trouble shooting procedure as
outlined in sections 10.4.2 through 10.4.7.
If the meter shows more than 220mVDC at test
point 17, then check for the following:
• Correct type of gas supplied
• Correct gas supply pressure
• Correct gas manifold pressure
• Correct orifi ce size
• Air in the gas line
If the main burners will not stay lit after checking
the items listed above, the gas valve may be causing
the fault. Replace the gas valve.
10.4.2 Pilot Generator
The pilot generator generates a 700-750mVDC
signal when heated by the pilot fl ame. When the pilot
generator is connected to the heater's control compo-
nents, there will be some voltage drop in the circuit so
that the measured voltage will be less than 750mVDC.
But the measured voltage should never be below
500mVDC when the ON/OFF switch is in the "OFF"
position or 220mVDC when the ON/OFF switch is in
the "ON" position.
With the pilot generator connected to the gas
valve and the ON/OFF switch in the OFF position,
place the red lead of the voltmeter on the PP terminal
(test point 1) of the gas valve. Place the black lead
of the meter on the PP/TH terminal (test point 2) of
the gas valve. The meter should show a minimum of
500mVDC. If the meter show less than 500mV, check
for partial shorts, loose or corroded connections or
partially broken wires between the pilot generator and
the gas valve.
If the wires and connections are sound, check the
pilot generator output. You will need alligator clips
to do this. Disconnect the pilot generator from the
gas valve. The pilot will go out. Light the pilot while
pressing down on the gas valve control knob. Continue
holding the knob for at least one minute. Immediately
measure the voltage between the two wires of the pilot
generator. If the meter does not show at least 700mV,
replace the pilot generator.
10.4.3 Fusible Link
Check the voltage going to the safety circuit. Be
sure that the pilot generator is correctly wired to the
gas valve, the pilot is lit and the control knob on the
gas valve is in the "PILOT" position. Leave the red
voltmeter lead in place at test point 1. Touch the black
Model LRZM Pool/Spa Heater Installation and Operation Manual
™
lead of the meter to the terminal of the fusible link
where the white wire from the gas valve is connected
(test point 3).
If no voltage is detected at test point 3, the wire
between the gas valve and the fusible link is broken.
Replace the wire.
If there is a minimum of 220mV at test point 3,
move the black meter lead to the other terminal of the
fusible link (test point 4).
If no voltage is detected at test point 4, the
fusible link has failed. This indicates higher than
normal temperatures in the component compartment
(vestibule). Normal component compartment tempera-
ture is well below 300
F. The fusible link is designed
o
to fail at temperatures above 305°F. Excessive temper-
ature might be due to a blocked fl ue or heat exchanger.
Clean the heat exchanger and clear the fl ue and vent
of any restrictions. Sometimes the fusible link fails
due to fl ame roll-out. Flame roll-out may be caused
by delayed ignition or downdrafting in windy areas.
Thoroughly investigate the causes for fl ame roll-out
and correct the problem when replacing the fusible
link.
10.4.4 Fireman Switch and External
Interlocks
Check the voltage going to the external device.
Touch the black lead of the meter to the fi reman switch
terminal strip where the white wire from the fusible
link is connected (test point 5). The meter should read
at least 220mV. If the voltage is less than 220mV, there
may be a bad connection or wire between the fusible
link and the terminal strip. The wire may need to be
replaced. If voltage of 220mV or more is detected at
test point 5, move the black lead of the meter to the
fi reman switch terminal strip connection where the
white wire from the high limit is connected (test point
6). The meter should read at least 220mV. If there is no
voltage, the time clock switch or other external inter-
lock may be mis-adjusted, mis-connected or defective.
Correct this external problem.
10.4.5 Limit Switches
Since the limit switches are not easily accessible,
you can check the voltage going into the component
after the limit switches in the circuit. If voltage is
detected there, then the limit switches are closed and
are operational.
Check the voltage going to the water pressure
switch. Leave the red voltmeter lead in place at test
point 1. Touch the black lead of the meter to the termi-
nal of the water pressure switch where the white wire
is connected (test point 11).
If the voltage is less than 220mV, there may be
a bad connection, a partial short or a faulty sensor. If
there is no voltage, one of the limit switches is open.
This is normally due to excessive water tempera-
Advertisement
Table of Contents
Troubleshooting
