Astralpool IXI / Zodiac JXi 370 Heat Exchanger Assembly - R0589405
Astralpool IXI / Zodiac JXi 370 Heat Exchanger Assembly - R0589405 is temporarily out of stock and will ship as soon as it's available.
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Warranty Information
Warranty Information
Astralpool IXI / Zodiac JXi 370 Heat Exchanger Assembly - R0589405
Astralpool IXI / Zodiac JXi 370 Heat Exchanger Assembly - R0589405 is temporarily out of stock and will ship as soon as it's available.
Astralpool IXI / Zodiac JXi 370 Heat Exchanger Assembly - R0589405
This is the genuine Zodiac heat exchanger assembly, part number R0589405, for Astralpool IXI and Zodiac JXi gas pool and spa heaters. It suits the 370 size only (Astralpool IXI 370 and Zodiac JXi 370). On the parts diagrams it is item 11 on the combustion chamber diagram.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, WA, QLD
What This Part Does
Water flows through the heat exchanger, which surrounds the burner and transfers its heat to the water (Astralpool IXI manual, section 2.4). It is item 11 on the JXi / IXI combustion chamber diagram, and Zodiac lists a different assembly for each heater size: R0589405 for the 370 and R0589402 for the 200.
Water balance matters for heat exchanger life. The IXI manual warns that if pH rises above 7.8 without calcium hardness and total alkalinity properly maintained, calcium can coat the copper tubes inside the heat exchanger, restricting flow, reducing efficiency and possibly damaging the heater. If pH drops below 7.2, acidic water can dissolve copper tubing. Damage to the heat exchanger caused by improper water chemistry is not covered by the warranty.
The Rating Plate Rule (rev. IXJ-1.0)
Identify the part by the heater it came from:
- Find the rating plate. It is inside the heater, on the outside of the combustion chamber, and shows the model number, serial number and gas type. Zodiac's JXi manual says these are needed to identify the correct part.
- Check the badge. Astralpool IXI and Zodiac JXi heaters use the same part number for this part, so either badge is fine.
- Check the size. This part is for the 370 only. If the rating plate says 200, order R0589402 instead.
- Match the diagram. On the combustion chamber diagram this part is item 11. The diagrams are on our IXI / JXi parts page.
Worked Example
Say the rating plate reads Zodiac JXi 370. The 370 takes R0589405 and the 200 takes R0589402, so R0589405 is the part to order. An Astralpool IXI 370 takes the same R0589405.
Confirmed Compatibility
- Zodiac JXi: 370 only
- Astralpool IXI: 370 only
- Not for: the 200 size, which takes R0589402
Which Part Do I Need?
| What you have | What to order |
|---|---|
| Astralpool IXI 370 or Zodiac JXi 370 | This heat exchanger assembly, R0589405 |
| Astralpool IXI 200 or Zodiac JXi 200 | 200 Heat Exchanger Assembly R0589402 |
Part Numbers and Cross-References
- Zodiac / Astralpool part number: R0589405
- Barcode: 9317545024332
- Jandy / Zodiac USA: the US Jandy JXi parts list uses the same number, R0589405
- Diagram item: 11 on the combustion chamber diagram
Other Combustion Chamber Parts
- Item 3: Refractory Kit, Internal (R0590500)
- Item 4: Combustion Chamber Shelf, 200 only (R0590701)
- Item 5: Combustion Chamber Lid Kit (R0590800)
- Item 8: Igniter Kit (R0457502)
- Item 11: 200 Heat Exchanger Assembly (R0589402)
Fitting Notes From the Manual
A summary for the qualified technician doing the job. It does not replace the manufacturer's manual.
- The heater must be installed and serviced by a gas fitter licensed and qualified in pool equipment, in accordance with AS/NZS 5601.
- Before opening the heater, turn the controller off, turn off all electrical power to the heater and shut off the external gas supply valve.
- Test all gas connections for leaks with a soap solution. Never use an open flame to test for leaks.
- Verify proper operation after servicing. Don't use the heater if any part has been under water; have a qualified service technician inspect it first.
Frequently Asked Questions
Does it fit the Astralpool IXI as well as the Zodiac JXi?
Yes, in the 370 size. The Astralpool IXI 370 and the Zodiac JXi 370 use the same part number, R0589405.
Does it fit both the 200 and the 370?
No. R0589405 is for the 370 only. The 200 takes R0589402.
Is heat exchanger damage covered by warranty?
Not when it is caused by water chemistry. The IXI manual says damage to the heat exchanger caused by improper water chemistry is not covered by the warranty, so keep the pool water balanced.
Is this a genuine part?
Yes. Heater and Spa Parts is an authorised Fluidra (Astralpool and Zodiac) dealer and warranty agent, and this is the genuine R0589405.
Manufacturer Catalogues, Diagrams & Part Numbers
Need exploded views, spare part numbers, product numbers or diagrams? See the manufacturer catalogues: Zodiac Catalogue 2026 | Astralpool Catalogue 2026. The exploded diagrams for these heaters, with every IXI / JXi part we list, are on our Astralpool IXI / Zodiac JXi Gas Heater Parts page.
Before ordering: confirm this part is correct for your equipment. Use the catalogues above, seek professional assistance, or contact us with photos of your existing part, model details, serial numbers and any labels. As with all products, this must be diagnosed and fitted by a qualified and experienced person.
Common search terms: Astralpool IXI 370 Heat Exchanger Assembly, Zodiac JXi 370 Heat Exchanger Assembly, R0589405, IXI 370 heat exchanger assembly, JXi 370 heat exchanger assembly, Jandy R0589405, IXI gas heater parts, JXi heater parts, WWDG SpaPro.
To the layperson, plumbing sizes and their names can be confusing due to the nominal sizes and naming conventions used.
This is not something we made up. Plumbers and manufacturers have used nominal (meaning ‘by name only’) sizing for decades.
Simply put, in plumbing, named sizes are often not the actual measurements of the pipe, fitting, or part. A PVC pipe called “50mm” or “2"” does not measure 50 mm anywhere. Instead, it follows nominal sizing, an internationally-standardised naming system.
Almost all fittings we use in the pool & spa industry use “pressure PVC” pipe & fittings. Do not confuse with “DWV” or other pipe & fittings and their names and sizes.
Use the Outside Diameter (OD) to check your pipe against fittings. Below is a quick reference for common spa & pool pipe sizes:
| Imperial Name | Metric Name | Pipe Diameter (OD) |
|---|---|---|
| 1/2" | 15mm | ~21.2–21.5 mm |
| 3/4" | 20mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 mm |
| 2.5" | 65 mm | ~75.2–75.5 mm |
To reiterate, these are nominal sizes and are designed to fit matching fittings — not to measure what their name suggests. These are based on PVC Pressure Pipe AS/NZ 1477 Dimensions1.
- º Internal diameters vary slightly by manufacturer and class.
- 1 Not all pool/spa fittings match these dimensions exactly. Some do not follow Australian or international standards. Chinese spas may use proprietary fittings.
Understanding Plumbing Sizes & Nominal Measurements
Plumbing sizes can be confusing. PVC and many other pipe systems use nominal sizes—the size is a name, not the exact measured dimension. This convention is used across most pool and spa systems and other plumbing areas so that pipes and fittings remain compatible.
Why pipe sizes don’t match the measurements
The Nominal Pipe Size (NPS) system standardises pipe dimensions so that pipes, fittings, valves, and accessories interoperate.
Plumbers work with these nominal names every day, but DIYers can be tripped up if they try to match by a tape-measure alone.
How to Measure Pipe Correctly
-
Pipe size is identified by:
- The pipe’s Outside Diameter (OD).
- The fitting’s Inside Diameter (ID) (socket opening).
- Pipe Class / Schedule (e.g., Class 9, 12, 18 or Sch 40) relates to wall thickness and therefore the Internal Diameter (ID) and pressure rating.
- The outside diameter of a fitting is not useful (wall thickness varies by manufacturer).
Hose & Tube Dimensions
Common flexible hose sizes used in pool/spa systems (approximate IDs).
| Imperial Name | Metric Name | Inside Diameter (ID) |
|---|---|---|
| 3/8" | 9–10 mm | ~9 mm |
| 3/4" | 19 mm | ~19 mm |
BSP – British Standard Pipe Thread Sizes
BSP thread names are also nominal. The thread OD will not equal the nominal name.
| BSP Thread Size Naming | Outside Diameter (mm / inch) | TPI |
|---|---|---|
| 1/16" BSP | 7.7 mm / 0.304" | 28 |
| 1/8" BSP | 9.7 mm / 0.383" | 28 |
| 1/4" BSP | 13.16 mm / 0.518" | 19 |
| 3/8" BSP | 16.66 mm / 0.656" | 19 |
| 1/2" BSP / 15 mm | 20.99 mm / 0.825" | 14 |
| 5/8" BSP | 22.99 mm / 0.902" | 14 |
| 3/4" BSP / 20 mm | 26.44 mm / 1.041" | 14 |
| 7/8" BSP | 30.20 mm / 1.189" | 14 |
| 1" BSP / 25 mm | 33.25 mm / 1.309" | 11 |
| 1-1/4" BSP | 41.91 mm / 1.650" | 11 |
| 1-1/2" BSP / 40 mm | 47.80 mm / 1.882" | 11 |
| 2" BSP / 50 mm | 59.61 mm / 2.347" | 11 |
| 2-1/4" BSP | 65.71 mm / 2.587" | 11 |
| 2-1/2" BSP | 75.18 mm / 2.960" | 11 |
| 3" BSP | 87.88 mm / 3.460" | 11 |
| 4" BSP | 113.03 mm / 4.450" | 11 |
| 5" BSP | 138.43 mm / 5.450" | 11 |
| 6" BSP | 163.83 mm / 6.450" | 11 |
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R0589405
