Astralpool Hurlcon Gas Heater & Halo Temperature Sensor - Thermistor - HX JX MX Viron ICI HiNRG Halo
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Delivery and Shipping Info*
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Astralpool Hurlcon Gas Heater & Halo Temperature Sensor - Therm...
Genuine AstralPool / Hurlcon temperature sensor lead, also known as a thermistor lead, for most AstralPool and Hurlcon gas pool and spa heaters with a digital thermostat. Also used in Astralpool Halo temperature sensor kits.
This replacement sensor is commonly used to correct incorrect water temperature readings, sensor-related thermostat faults, and F0 / FO temperature sensor errors on many post-2001 Hurlcon and AstralPool heaters.
HASP carries more pool and spa parts in physical stock than anyone. Shipping from VIC, NSW, QLD and WA.
Part Details
- Part type: Temperature sensor lead / thermistor lead
- Manufacturer: AstralPool / Hurlcon
- Part number: 70276
- Length: ~1.5m
- Commonly called: Temp sensor, temperature sensor, thermistor, sensor lead
- Replaces: Older black, red and yellow wired temperature sensor leads on compatible digital thermostat heaters
Compatible AstralPool & Hurlcon Heaters
This sensor suits many post-2001 digital thermostat AstralPool and Hurlcon gas heaters & Halo controllers, including the following model families:
- HX Series: HX 70, HX 120, HX 150
- WX / Wilton Series: WX 70, WX 75, WX 120
- MX Series: MX 125, MX 150, MX 200, MX 250, MX 300, MX 350, MX 400, MX 500
- JX Wall-Mount Series: JX 130, JX 160
- Viron & Viron eVo Series: Viron 250, Viron 350, Viron 450
- HiNRG Series: HiNRG 175, HiNRG 250, HiNRG 400
- ICI Series: ICI 200, ICI 400
- Hurlcon Boilers: HB 200, HB 250, HB 300, HB 400, HB 500
- Jacuzzi gas heaters: J-HN250C, J-HN400C
- Halo Chlorinator Control Systems
Viron Heat Exchanger Sensor Note
On some Viron heaters, this sensor is also used as the heat exchanger temperature sensor. Check your existing sensor location and wiring before ordering.
F0 / FO Error & Fault Diagnosis
- A failed or wet temperature sensor can cause an F0 / FO fault.
- It may also cause incorrect or unstable displayed water temperature readings.
- The heater’s displayed temperature is based on water passing through the heater, so the pump must be operating correctly for the temperature reading to be meaningful.
- If the fault returns after replacing the sensor, check the brass well, wiring, thermostat PCB and overall heater condition.
Important Brass Well Information
Temperature sensors often fail because water has leaked into the brass sensor well. If the old sensor is swollen, corroded, difficult to remove, or the well has water inside it, the brass well should also be replaced.
Some newer replacement sensors can be slightly larger than earlier sensor leads. If the sensor does not fit correctly into the old well, replace the brass well rather than forcing the sensor.
Related Heater Parts
Check Before Ordering
- This part is for compatible digital thermostat heaters.
- Older analogue thermostat heaters may use different parts.
- Confirm your heater model, sensor style and wiring before ordering.
- For help identifying the correct part, send photos of your heater, control panel, existing sensor and brass well to info@hasp.com.au.
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
Interactive Parts Diagrams
Find this part on our interactive heater parts diagrams — each one opens the full exploded view and parts list:
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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