MP indoor SS single coil for closed loop solar Ø550mm



** Superseded Jul 2022, please order the the improved Ø560mm cylinders**

If you're keen on utilising solar energy then this hot water cylinder is for you. The coil design is created for use with closed loop solar systems. This is where the heat transfer fluid is circulated through the solar collector on the roof where it is heated by the sun. The heated transfer fluid then passes through the cylinder coil, which acts like a very large element to heat the water.

The unique coil spirals down and then wraps back up around itself creating a coil within a coil. It is located at the very bottom of the cylinder to allow for maximum heat to be transferred to the water in the cylinder.

The duplex stainless steel inner cylinder means it can be used is solar systems with high incoming water temperatures.

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Product Details

Suitable for:
- indoor installations only
- mains and low pressure systems
- connection to closed loop solar systems
- residential and light commercial water heating applications

No suitable as a pool or spa heater, or for underfloor heating.

Water quality
Rinnai cylinders are manufactured to suit most NZ council water supplies. However some supplies can have a detrimental effect on the cylinder, its operation and life expectancy.  Stainless steel cylinders are not suitable for bore or tank water.

Single coil lower element
For new builds and renovations connecting to a closed loop solar system, where the homeowner wants constant hot water, whether there is solar gain or not.

Single coil dual element
For new builds and renovations connecting to a closed loop solar system, where the homeowner wants faster recovery times, and to reduce the risk of running out of hot water regardless of solar gain. Cylinder will have higher running costs.

Single coil upper element
For new builds and renovations connecting to a closed loop solar system, where the homeowner relies heavily on solar gain. Upper element is only used to quickly heat water in the top of the cylinder.

Technical Specifications


10 years

IP rating




Single coil lower element codes
  • 190 L 2 kW - MS190550C20
  • 190 L 3 kW - MS190550C30
  • 250 L 2 kW - MS250550C20
  • 250 L 3 kW - MS250550C30
  • 300 L 2 kW - MS300550C20
  • 300 L 3 kW - MS300550C30
Single coil upper element codes
  • 250 L 2 kW - MS250550CU20
  • 250 L 3 kW - MS250550CU30
  • 300 L 2 kW - MS300550CU20
  • 300 L 3 kW - MS300550CU30
Single coil dual element codes
  • 250 L 2 kW - MS250550CD20
  • 250 L 3 kW - MS250550CD30
  • 300 L 2 kW - MS300550CD20
  • 300 L 3 kW - MS300550CD30

Inner, high grade duplex stainless steel
Outer, galvanised steel


CFC free polyurethane foam, compliant with NZ MEPS


Hot and cold connections ¾ " (20 mm)
TPR ½ " (15 mm)

  • Solar coil ¾ " 20 mm diameter
  • Length = 14 m (1.1 m2)
  • Maximum kW output 21.4 kW

Incoloy 825 alloy sheath element, options; 2 kW, 3 kW, 2 x 2 kW, and 2 x 3 kW


Robert Shaw 30 A contact auto-reset (red dial)


TPR supplied, 850 kPa, 99 °C, 10 kW

Pressure limiting valve

This cylinder MUST be installed with a 500 kPa or less pressure limiting valve and appropriate cold water expansion valve.

Model Empty Full
190 L 42 kg 232 kg
250 L 48 kg 298 kg
300 L 56 kg 356 kg

No cylinder wrap required. All Rinnai cylinders meet the NZ Minimum Energy Performance Standard (MEPS).

Market release

September 2017


Superseded Jul 2022 by the improved Ø560mm cylinders.

Common spares
  • Thermostat Robert Shaw red dial (ART solar) - 30015
  • Element MP SS 2 kW curved - 30002
  • Element MP SS 3 kW curved - 30004
  • TPR MP 850 kPa 15 mm - 30018