Rheem heavy duty 275

Rinnai Demand Duo 1 One Commercial Heavy Duty Gas Hot Water System

Replacement for the Rheem Heavy Duty 275 Litre Gas Hot Water System

The perfect solution for your new or replacement storage hot water needs.

If your existing gas storage heater has failed, the Rinnai Demand Duo 1 is the simple, fast, high efficiency hot water solution. Available in natural gas or LPG versions with internal or external options, all with a 250 litre Stainless Steel storage tank, there is a model to suit your exact requirements. The Rinnai Demand Duo 1 is lightweight yet robust in construction, allowing for easy transportation into those hard to get at places. With warranties of up to 10 years the Rinnai Demand Duo 1 offers peace of mind, and years of consistent performance.

Features & Benefits:

• Australian made Stainless Steel storage tank – 444 Grade

• Lightweight construction for ease of handling

• Robust, high quality design

• 1010 litre first hour delivery @ 50 Degree C temperature rise (DD1 200 250)

• Over 83%*thermal efficiency offering, lower running costs with significant energy savings

• High efficiency means reduced gas bills and carbon footprint compared to other generic gas storage water heaters

• Modular yet integrated design means individual components can be replaced as necessary, no need to replace the whole system

• The Rinnai Flue Adaptor (DD1FADAPT) is available for simple, trouble free replacement for internal installations

• Innovative on-board thermostat with LCD display with multiple set temperatures from 65° to 80°

Posted by Shannon C in Hot Water Systems

Rinnai Gas Hot Water Mains Pressure Tank System Addon. Booster or Supercharger

Rinnai Infinity Domestic or Commercial Gas Mains Pressure Hot Water System Tank Addition

Turn your Rinnai B26 or Infinity 26 which is a 15 litre per minute hot water system at 50-55 degrees into a FULL FLOW – Mains Pressure 780 Litres in the first hour*  mains pressure hot water system that can supply hot water to as many taps as you wish based on the storage tank size you select and your current pipe sizing. This is close to a Rheem Heavy Duty 275 Litre and the Rinnai Demand Duo Commercial Hot Water Systems costing around $6900 just for the hot water unit.

*(small 50 litre storage tank. 80 litre extra $200, 125 litre tank extra $400. Larger tank options and Multiple Rinnai Infinity 26 connected together for larger hot water requirements) Case Study below.

Hot Water System Tank Addition

This system addon is only $1990 Incl GST Installed and Supplied.

Tank recovery 3.5 minutes.

System is made up with a Rinnai/ Rheem Storage Tank and a Grundfos or Davey Hot Water Circulating Pump. Manifold is suit the individual installation

A Rinnai 26 or Builders B 26 can support 2 showers at the same time.  They increase the water temperature 20 degrees at a rate of 26 litres per minute. They need to reduce the water flow so they can produce 50-60 degree temperatures at the tap.  The reduced flow rate is dependent on the cold water supply temperature.  If the cold water temperature is 15 degrees at a 26 litre per minute flow rate the water will be only 35-40 degrees(20-25 degree increase at 26 litres per minute).  The Rinnai 26 or b26 reduces the flow rate down to say about 15-18 litres per minute so as to achieve the desired temperature of 50-60 degrees.

Where the Rinnai Mains Pressure Tank System comes into it’s own is that the same flow rate and pressure you get from the cold water tap you will have with the hot water tap also.  The beauty here is that the Rinnai heats up the water in the tank at a very rapid rate and at a excellent 6.1 energy rating.


Say you have a small holding or hot water storage tank of 50 litres set at 53 degrees.  4 showers running using 9 litres per minute or 24 litres per minute at 40 degrees at the shower. Cold water temperature of 15 degrees and a Rinnai flow rate at a set 53 degrees at the tank but 50 degrees at the tap outlet(heat loss). One Rinnai 26 or Builders B26 supporting the small 50 litre tank will last for 9 minute with the taps running constantly. It will hold above 40 degrees for 30 minutes. It will also fully recover in 3.5 minutes to 53 degrees or in 16 minutes with only 2 showers being used.

Case Study.

We installed this system in Manly which has 21 one bedroom apartments. 21 Kitchens and bathrooms. The tank size is 250 litres and only one Rinnai 26 needed. They wanted a second Rinnai Infinity 26 installed only as a back up.  This system has been working with out a problem for 5 years now.

Posted by Shannon C in Hot Water Systems