MP indoor stainless steel single standard coil for closed loop solar


For connection to closed loop solar systems

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


Hold 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

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


In all Rinnai cylinder instructions, we mandate the use of a drip tray. This is because all cylinders have the potential to leak water and cause extensive damage. Our instructions state: The Rinnai warranty does not cover any consequential loss from leaks to the cylinder, so it’s important a suitably drained drip tray/catch pan is fitted as per AS/NZ 3500.4:2015 5.4 and G12/AS1 6.11.3. Like-for-like replacements are a grey area as most installers will only replace the cylinder to the same configuration as the cylinder that is being replaced. In these instances, Rinnai still maintains that a drip tray should be fitted. This protects the homeowner and the building from any future problems should a leak occur. If a drip tray cannot be fitted, then look at other possible options such as: • Locating the cylinder outside • Using a continuous flow gas hot water heater
* As the world’s largest gas appliance manufacturer, Rinnai is widely regarded as the industry leader. * Rinnai products are known throughout the world for their superior quality, safety, technology and sophisticated control systems, all factories are ISO 9001 and/or ISO 14001 certified. * We have an established 40 year history in New Zealand. * Rinnai are happy to advise that we now have an IANZ accredited Test Lab for MEPS testing on Hot Water Cylinders. The lab uses the latest in test equipment and can test all type of Hot Water Cylinders for MEPS heat loss testing.
We realise there's a lot of information out there. Water heating is important and it's better to spend the time up front deciding on what you need and what's important. We have an experienced customer service team that can walk you through the process. For those more complicated projects we also have a free specification service. Give us a call: 0800 RINNAI (0800 746 624)
Installation costs are difficult to provide as every installation is different. Factors such as the length of pipe required, whether you have accessories fitted, how far away you live and choosing an internal or an external unit all influence the overall cost. If you’re interested in a Rinnai hot water heating solution, we highly recommend you contact a plumber/gas fitter who will be able to explain all the options to you.