HJ Cooper Mains Pressure Stainless Steel Coiled Cylinders


Discontinued range 2015-2017, superseded by Rinnai branded cylinders

This range of electric mains pressure hot water cylinders comes with a 10 year warranty on the inner cylinder, and is backed by Rinnai after sales service and support.

Coiled range consists of:

  • Thermosiphon single and twin coil 
  • Non-thermosiphon single coil 
  • Non-thermosiphon twin coil 

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Product Details

Thermosiphon single and twin coil
Twin coil for connection to a wetback fire and a glycol solar system. Single coil if connecting to a wetback fire and/or a potable solar system. The single coil cylinder has an extra eco connection that can be connected to an open loop (potable) solar system, or a hot water heat pump.

Non-thermosiphon single coil
For connection to a closed loop solar system. Coil design spirals down and then wraps back up and around itself creating a coil within a coil. It is located at the very bottom of the cylinder to allow for maxim heat to be transferred to the water in the cylinder.

Non-thermosiphon twin coil
The coil design is created for use with glycol solar systems and connection to indoor boiler systems with radiators for home heating.

All mains pressure coiled cylinders are suitable for:

  • indoor installations only
  • mains and low pressure systems
  • residential and light commercial heating applications

They are not suitable as a pool or spa heater, or for underfloor heating.

Thermosiphon single coil Connection to a wetback fire or open loop solar system
Thermosiphon twin coil Connection to a wetback fire and closed loop solar system
Non-thermosiphon single coil Connection to closed loop solar systems
Non-thermosiphon twin coil Connection to closed loop solar and boiler systems

Technical Specifications

  • Inner cylinder, duplex stainless steel
  • Outer casing, galvanised steel
  • Insulation, CFC free polyurethane foam compliant with NZ MEPS

Hot and cold connections ¾ " (20 mm)
Coil connections ¾ " (20 mm)

Wetback coil

Auxiliary coil 20 mm diameter
Coil length - 11 m (0.86 m2)
Coil kW rating - nominal 22 kW

Solar coil

20 mm diameter


Incoloy 825 alloy sheath element positioned at the bottom of the tank

  • 190 L: 2 kW or 3 kW (non-thermosiphon single coil only)
  • 250 L: 2 kW or 3 kW
  • 300 L: 2 kW or 3 kW

Twin element options available


Robert Shaw 30 A contact auto reset thermostat


Supplied, factory set to 850 kPa and 90 °C

Weights empty
Thermosiphon single coil 250 L 49 kg
Thermosiphon single coil 300 L 56 kg
Thermosiphon twin coil 250 L 55 kg
Thermosiphon twin coil 300 L 62 kg
Non-thermosiphon single coil 190 L 42 kg
Non-thermosiphon single coil 250 L 48 kg
Non-thermosiphon single coil 300 L 56 kg
Non-thermosiphon twin coil 250 L 56.5kg
Non-thermosiphon twin coil 300 L 66.5 kg
Superseded / last sold
  • Thermosiphon single and twin coil, superseded Sep 2017 by Rinnai branded cylinders
  • Non-thermosiphon single coil, as above
  • Non-thermosiphon twin coil, last sold Aug 2015