Waterpik Technologies LG - Manual (Page 31)

Model LG Pool and Spa Heater Page 29
FLUE COLLECTOR
HEAT EXCHANGER
COMBUSTION CHAMBER
BURNER
BURNER TRAY SHELF
VENT TOP
EXHAUST
AIR
FLOW
Figure 23. Atmospheric Combustion System
desired temperature. The desired temperature is
set by rotating a knob on the face of the control
panel. To achieve accurate water temperatures,
the pool/spa water must be monitored with an
accurate pool thermometer.
3. Pilot/Pilot Ignition
The LG heater relies on a standing pilot to ignite
the burners when the temperature control calls
for heat. When lit the pilot receives a constant
flow of gas from the gas valve. If the pilot
exstinguishes, the gas valve is automatically
signalled to stop the flow of gas to the pilot and
the burners to prevent a gas build up in the
heater. Igniting the pilot is achieved by means of
a piezo spark igniter mounted on the inner front
panel of the controls compartment of the heater.
4. Pilot Generator (Thermopile) - The pilot
generator is a device, that when heated by the
flame of the pilot, generates a small electrical
voltage of approximately 750 millivolts. The
voltage is placed across the temperature control-
ler and safety circuit of the heater. If this current
is broken at any time, the gas valve is immedi-
ately shut off and the heater stops firing. This
voltage is also used to activate the gas valve's
pilot coil which allows gas to flow to the pilot
after the gas valve knob is released.
5. Limit Switches - Two limit switches prevent
excessive water temperature - one within the heat
exchanger and one for water leaving the heater.
If either senses excessive temperature, burner
operation is interrupted.
6. Water Pressure Switch - This control senses
whether or not water is available to the heater by
measuring back pressure inside of the heat
exchanger. If the pool water pump fails or the
water filter is blocked, the pressure switch
prevents operation of the burner.
7. Fusible Link - This is a single-use switch which
detects abnormal temperature in the component
vestibule. It is a fusible link which is held to the
inner panel just above the burner tray by a sheet
metal bracket. Excessive temperature in the
component compartment, possibly due to a
blocked flue or flame roll-out, will cause the link
to fail. This opens the safety circuit which shuts
off the gas valve and shuts the heater down.
10.4 Electrical Troubleshooting
This section describes procedures for checking
the pilot generator and control components of the
heater one at a time and in the order they appear in the
control circuit.