The Jandy R0589405 Heat Exchange Assembly is the genuine OEM heat exchanger tube for Jandy JXi and JXiQ 400,000 BTU gas pool and spa heaters. It is the core component that transfers combustion heat from the burner into the water, and it is the single most common major-repair part on this heater family.

When This Is the Part You Need

A failing heat exchanger typically shows up as a heater that runs but produces little or no temperature rise, a persistent high-limit or flow-related lockout with no obvious blockage, visible corrosion or scale at the tube fittings, or a water leak from inside the heater cabinet rather than the plumbing unions. Because the exchanger sits at the center of the heat path, most other JXi 400 heating complaints trace back either to this part or to the igniter and gas valve.

Key Features

• Genuine Jandy OEM: factory tube assembly built to the exact specification of the original equipment.
• Restores full heat transfer: returns the heater to its rated 400,000 BTU output.
• Corrosion-resistant construction: built to withstand continuous exposure to chemically treated pool and spa water.
• Direct bolt-in replacement: matches the mounting and plumbing connections of the original exchanger.
• Covers the full JXi/JXiQ 400 lineup: one part serves the natural gas and propane variants across the model range.

Compatible Heaters

• Jandy JXi 400: JXi400NC, JXi400NK, JXi400NN, JXi400PC, JXi400PK, JXi400PN
• Jandy JXiQ 400 heaters

Specifications

• Part Number: R0589405
• Type: Heat exchange assembly / heat exchanger tube replacement
• BTU Rating: 400,000 BTU
• Approximate Shipping Weight: 43 lb
• Brand: Jandy / Zodiac (Genuine OEM)

Frequently Asked Questions

Does this include the burner, igniter or gas valve?

No. This is the heat exchange assembly only. If your heater is failing to ignite rather than failing to transfer heat, check the igniter and gas valve first — those are separate parts.

How do I know if the heat exchanger is the problem?

The classic sign is a heater that fires normally, runs through a full cycle, and still produces little or no water temperature rise, often alongside a high-limit trip or a leak from inside the cabinet. A qualified technician can confirm with a visual inspection for corrosion, scaling, or a cracked tube.

Will this fit my JXi 400?

It fits the JXi400 and JXiQ400 model range listed above. Match the model and serial number on your heater's rating plate against your equipment manual before ordering, or send it to us and we will confirm the fit.

Who should install it?

A qualified pool professional or licensed gas technician. The heater must be isolated at the breaker and the gas and water supply shut off before the cabinet is opened, and the plumbing unions must be reconnected and pressure-tested correctly to avoid leaks.

California Proposition 65 Warning: This product can expose you to chemicals known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.