Jandy JXI Heaters

Jandy LXI Heaters is the prior model that shares much in common and may also have helpful information.

Sequence of Operation

The control system reads the temperature of the water
Start-up process begins if the temperature is below the set point
Blower starts, then adequate airflow is confirmed by the air pressure switch
After airflow is confirmed, the ignition sequence begins
After a 15-second purge, the igniter gets power
After approximately 40 seconds of igniter heat up, power is sent to the gas valve
The gas valve remains open for 5 seconds while the Ignition Control is looking for flame rectification
As long as flame is sensed at the burner, operation continues until the temperature of the water entering the heater reaches the temperature control setting.

The JXI heater does not have a pilot light. It is equipped with an ignition device which automatically lights the burner. DO NOT try to light the burners by hand.

Repairs

Workbook JXi Pool&Spa Heater is a training manual for pool repairmen.

BP Electronics or Industrial Electronic Repair has repaired Jandy heater boards. Check with them if your board needs replacement.^[1]

JXI Igniters

Silicon Carbide Hot Surface Ignitors are very fragile. That is why they come packed in thick foam packaging. After removing be sure not to bump, scrape or jar the black crystalline part of the ignitor. Also be sure not to touch or contaminate the black crystalline surface with your hands ( it can cause it to fail very similar to a halogen bulb that has been touched with your hands). Although these are not the only reasons for a hot surface ignitor to fail, they are basic precautions that need to be adhered to.

After installing check the resistance of the ignitor with a multimeter. A new ignitor should read approximately 40-90 ohms.^[2]

Jandy changed the igniter style a while back as the ones they originally used broke too easily. The old one was like a spiral design.

The new style is more of a solid looking piece.^[3]

Flame Rectification Failure

Does the heater briefly ignite and you get a puff of heat and then shuts down? If so you may have have a flame sensing problem. Heater Flame Sensing describes what may be happening and ways to fix it.

JXI High Limit Sensors

The JXI heaters have two high limit sensors, 135F and 150F, on the bottom rear of one side of the header assembly and the other on the upper front of the other side of the header assembly.^[4]

The sensors are simple switches that should be closed when the heater is off. Test the sensor using a multimeter and if it tests open then it needs replacement.

The sensors come as a set of two in a kit. If one fails the manual says to replace both. The 150F is the one with the smaller threads and will only fit that port.

Replacing Leaking Heat Exchanger in Jandy JXI Heater

Jandy JXI400N - Trouble Air describes how a member diagnosed the problems in his Jandy JXI400 heater, discovered the heat exchanger was leaking, and replaced the heat exchanger.

To check if the heat exchanger is leaking remove the ignitor and look into the burner can. If you see any water then you have a leak.