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Electric Water Heating

HJ Cooper by Rinnai enamel mains pressure hot water cylinders offer exceptional performance and reliability. With a range of slim diameters, they are an easy replacement option for your old electric hot water cylinder.

Peace of mind
Backed by Rinnai after sales support.

Energy Efficient

  • Curved element design ensures 98% of water is heated
  • No cylinder wraps required, all HJ Cooper cylinders meet NZ MEPS

MEPS = Minimum Energy Performance Standard


  • Large range of sizes (30-300 L), there's an electric hot water cylinder to suit 
  • Easy replacement, 488 mm and 590 mm diam. matches traditional NZ cylinder sizes
  • Auto reset thermostat option available for solar and hot water heat pump applications

Future proof your home

Eco inlet connection allows connection to an open loop hot water heat pump now or in the future—saving you up to 60% on your power bill.

Install as a low pressure system then connect, without replacing your cylinder, to the luxury of mains pressure when you are ready.

Suitable for:

  • Indoor installations
  • Mains and low pressure systems
  • Domestic water heating applications
  • Left or right hand plumbing connections 
  • Connection to open loop solar or hot water heat pump systems

Not suitable as a pool or spa heater.


Exceptional performance and reliability

Water quality

HJ Cooper water heaters are manufactured to suit most New Zealand council water supplies. However some water supplies can have a detrimental effect on the water heater, its operation and life expectancy.

Water supplies with a high level of calcium carbonate (hard water) can cause scaling on hot surfaces. We recommend a water temperature of no more than 65 °C to minimise scale build-up. Scale reducing or water softening devices should be considered in hard water areas. The unit is not guaranteed against damage due to scaling.