Astralpool Hurlcon Astralpool MX Gas Heater Spare Parts - MX125 thru MX400 - Choose From List
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Don't Guess - Ask Us!
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Delivery and Shipping Info*
Delivery and Shipping Info*
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Astralpool & Hurlcon MX Gas Heater Parts. Most parts are for models built 2000 thru to 2014. Build date should be in Sticker inside heater. Labeled as Hurlcon or Astralpool MX 125 / MX 150 / MX 200 / MX 250 / MX 300 / MX 350 / MX 400 / MX 500
The parts listed below are the only parts available, as these heaters are discontinued. We have listed the closest replacements below.
Recommended Replacement for discontinued MX Heaters:
- MX 125 / MX 150: Astralpool HX 120
- MX 200-250: Raypak 200 or Astral IXI 200 / Zodiax JXI 200
- MX 300: Raypak 280 or Astral IXI 200 / Zodiax JXI 200
- MX 400: Raypak 350, Raypak 430, Astral IXI 370 / Zodiax JXI 370
Spare Parts Below
Diagram 1:
- 1-18: Metal Panel Parts - No Longer Available
- 19. Complete Heat Exchangers - No Longer Available
- 20. Transformer
- 21. 70280 - Thermostat PCB
- 22-24: Metal Panel Parts - No Longer Available
- 25. Pressure Switch
- 26. Honeywell Smart Gas Valve - No Longer Available
- 27. Pilot Gas Tube (doesn't suit MX 500) - No Longer Available
- 28. Burner Rail - No Longer Available
- 29. Pilot HSI Smart Valve Assembly
- 30. Burner Tube - No Longer Available
- 31. Base Assembly - No Longer Available
Diagram 2:
- 1-2: Not pictured - No Longer Available
- 3. Return Header Manifold
- 4-6: Bolts & Baffle - No Longer Available
- 7. Complete Heat Exchangers - No Longer Available
- 8-9. In/Out Header Manifold - No Longer Available
- 10, 11, 12, 13: Bypass Assembly Parts
- 14, 15, 16: Barrel Union Plumbing Parts
- 17. Thermostat Brass Well
- 18. Inlet Hi-Limit 45° / Outlet Hi-Limit 52°
- 19. Bracket Retainer - No Longer Available
- 20. Tube Seal Gasket O-rings
- 21. Brass Plug for High-Limit
Not Shown in Diagram:
- 21a. Temperature Sensor / Thermistor
- Flue Kit: No Longer Available
Please Don't Order From This Page. Use The Links Above.
Manufacturer Catalogues, Diagrams & Part Numbers
Need exploded views, spare part numbers, product numbers, diagrams, or more product information? See the manufacturer catalogues: AstralPool Catalogue 2026 | Zodiac Catalogue 2026
In plumbing, named sizes are not the actual measurements. A pipe called “50mm” or “2"” does not measure 50 mm across. Instead, it follows nominal sizing, an internationally-standardised naming system.
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 |
These are nominal sizes and are designed to fit matching fittings — not to measure exactly 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 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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