Jandy Legacy LRZM, Installation And Operation Manual

Page 34

Legacy

™

 Model LRZM Pool/Spa Heater Installation and Operation Manual

2. 

Temperature Control 

- The Jandy Legacy 

controller is an electronic control which senses 

water temperature by means of a thermistor and 

controls heater operation to bring the water to the 

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 Legacy heater relies 

on a standing pilot to ignite the burners when the 

temperature control calls for heat. When lit the 

pilot receives a constant 

fl

 ow of gas from the gas 

valve. If the pilot extinguishes, the gas valve is 

automatically signalled to stop the 

fl

 ow 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 gener-

ator is a device, that when heated by the 

fl

 ame 

of the pilot, generates a small electrical voltage 

of approximately 750 millivolts. The voltage 

is placed across the temperature controller and 

safety circuit of the heater. If this current is 

broken at any time, the gas valve is immediately 

shut off and the heater stops 

fi

 ring. This voltage 

is also used to activate the gas valve's pilot coil 

which allows gas to 

fl

 ow 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 

fi

 lter 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 

fl

 ue or 

fl

 ame 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 check-

ing the pilot generator and control components of the 

heater one at a time and in the order they appear in the 

control circuit. 

NOTE

  Pump must be running during the 

troubleshooting procedure.

These procedures require a voltmeter with a 

minimum 0-1000 mVDC range. Figure 25 shows the 

pilot generator and control circuits, and where to take 

measurements. Location numbers and letters in circles 

have been added, and will be referenced in the follow-

ing sections.

As stated at the beginning of this manual, some 

of these procedures are hazardous. Only a quali

fi

 ed 

service technician should service the heater. 

During the trouble shooting procedure, the 

fi

 lter 

pump must be on, the pilot on the heater must be lit, 

the ON/OFF switch on the heater must be in the ON 

position and the control knob must be turned to the 

maximum setting so that there is a call for heat. We 

recommend turning the gas valve control knob to the 

"PILOT" position to prevent the main burners from 

fi

 ring throughout the procedure. Before starting the 

procedure, be sure that the pilot has been lit for at least 

2 minutes and that the pilot generator (thermopile) is 

positioned correctly within the 

fl

 ame of the pilot. 

The pilot generator also operates the pilot coil of 

the gas valve, allowing gas to 

fl

 ow to the pilot when 

the gas valve knob is released from the pilot light-

ing position (see Section 7.3 "Lighting and Shutdown 

Procedures"). If the pilot will not stay lit when the gas 

valve knob is released, check the pilot generator output 

as described in Section 10.4.2 and replace if necessary. 

If the pilot generator output is suf

fi

 cient, then check 

the gas valve as outlined in Section 10.4.1.

10.4.1 Gas Valve

The gas valve consists of two (2) separate 

internal operating valves. The main valve supplies 

gas to the main burners for heater operation. The pilot 

valve supplies gas to the pilot when the pilot generator 

activates the pilot coil.

If the pilot will not stay lit after following the 

lighting instructions in Section 7.3, check for the 

following:

• Pilot generator output

• Correct type of gas supplied

• Correct gas supply pressure

• Air in the gas line

• Pilot coil wire connections clean and tight

If the pilot will not stay lit after checking the 

items listed above, the pilot coil may be causing the 

fault. Replace the gas valve.