Astralpool Hurlcon Brass Plug for Hi-Limit Switches HX, JX, Viron, MX, HiNRG - also Jacuzzi

AstralPool / Hurlcon Threaded Brass Plug – 3/8" M4 with Hex Head

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