Astralpool Gas Heater Brass Plug - Hi Limit Locator - M4 16mm - ICI, Viron, HiNRG, HX, JX, MX

Astralpool Gas Heater Brass Plug - Hi Limit Locator - M4 16mm - ICI, Viron, HiNRG, HX, JX, MX

Astralpool / Hurlcon Gas Heater Threaded Brass Plug – 3/8" M4 with Hex Head. Used in HX, JX, MX, Viron, ICI, HiNRG gas heaters. High-limit switches screw into the top of these brass plugs in the heater manifold.

• Physically Stocked, unlike most "drop-shipping" websites.
• Shipped from VIC, NSW, WA, QLD

This genuine brass plug is used in Astralpool and Hurlcon gas heaters to accommodate high-limit (hi-limit) switches. The hi-limit sensor screws directly into this plug.

It is important to replace or repair these when leaking, and should be checked every 6-12 months. This can be one of the biggest causes of damage to gas heaters.

Suits: MX, HX, Viron, JX, ICI Heaters. Also suits Jacuzzi J-HN250C & J-HN400C heaters.

Common Issues:
These plugs can corrode over time due to poor water quality or if a small leak allows the 24V current from the hi-limit switch to create electrolytic corrosion. If the plug corrodes or leaks, it can lead to premature failure of the hi-limit switch.

Design Notes:

• Thread size: 3/8" M4
• Hex head for easy installation/removal
• Older versions had a 3/4" head and measured 13–16mm long
• Newer versions have a larger hex head and are 19–25mm long
• Fully interchangeable – just use extra thread tape and avoid overtightening
• Newer style is more robust and longer-lasting

Tip: See product photo for comparison between older and newer styles.

Installing:
Use Pink Thread Tape or a chemical-resistant thread sealant for Sealing threads. Care must be taken not to cause radial cracks in the header manifold around the female threaded area. <-- This is usually caused by over-tightening.

The red fibrous gaskets are no longer used. Use Teflon tape on the thread.

71053 old / 71060 new

Other High Limit (Hi Limit) Switches:

• 42-45C° Inlet Hi Limit (Hurlcon, Astralpool, Raypak, Pentair)
• 52-55C° Outlet Hi Limit (Hurlcon, Astralpool, Raypak, Pentair)
• 60C° Outlet Hi Limit AGS (Hurlcon, Astralpool, Raypak, Pentair)
• 70C° Outlet Hi Limit (Hurlcon, Astralpool HX/JX)
• 100C°
• 175C° Flue Temp Sensor (Hurlcon, Astralpool)
• Hurlcon / Astralpool HiLimit Locator Brass Threaded Plug

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