Rinnai HD28E Demand Duo User Guide

: September 15, 2024
: Rinnai

Table of Contents

Rinnai HD28E Demand Duo
Product Specifications
Product Usage Instructions
FAQ
What is a Demand Duo?
Heart of the system
Demand Duo Standard Options
- Demand Duo using multiple HD’s
Solutions and Accessories
Selecting a Demand Duo System
What information do I need?
Specifications
Warranty Info
ABOUT COMPANY
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Rinnai HD28E Demand Duo

Product Specifications

Product Name: Demand Duo
Origin: Designed and made in Australia (HD water heaters manufactured in Japan)
Components: Heavy Duty Continuous Flow Water Heaters, storage tank, primary pump(s), controller
Efficiency: Non-Condensing (83% Thermal Efficiency) and Condensing (97% Thermal Efficiency)
Water Flow Rate Options: HD28E 28l/min, HD28I 28l/min, HD32E 32 L/Min, HD210E 32 L/Min, HD210i 32 L/Min

Product Usage Instructions

How Does It Work?
A Demand Duo system consists of one or more Heavy Duty water heaters, manifolded in parallel, along with a storage tank, primary pump(s), and a controller. The controller monitors the water temperature in the tank and activates the primary pump when the temperature drops below the set value. This triggers the Continuous Flow water heaters to heat water and return it to the tank.

Key Benefits:

Efficient heating system
Hydraulic separation between primary and secondary loops
Balances pressure between cold and hot water

Suitable Applications:
The Demand Duo system is ideal for centralised hot water systems in various settings, such as commercial buildings, hotels, and large residential complexes.

FAQ

What are the key benefits of the Demand Duo system?
The key benefits include efficient heating, hydraulic separation, and pressure balancing between cold and hot water.
What are the suitable applications for the Demand Duo system?
The Demand Duo system is suitable for use in commercial buildings, hotels, and large residential complexes where a centralised hot water system is required.

What is a Demand Duo?

A Rinnai Demand Duo is a combination of Heavy Duty Continuous Flow Water Heaters that maintain the temperature in a heavily insulated storage tank. The storage tank acts as a hydraulic separator between the primary and secondary loop of the Hot Water System whilst balancing the pressure between the cold and hot water.
Demand Duos are designed and made in Australia (HD water heaters manufactured in Japan) and backed by Rinnai’s global commitment to quality.

How does it work?

As a complete packaged storage hot water system a Demand Duo is made up of one or more HD water heaters Manifolded in parallel, primary pump(s), controller and a storage tank.
The inbuilt controller detects the temperature of the water in the tank and when it drops below the set value, the primary pump is activated. This flow in turn activates the Continuous Flow HD Water Heater(s) which returns heated water to the tank.
Packages are available in standard customisable form or as a complete engineered system mounted on a skid base. Both are supplied in modular form for ease of installation and transport. In a Single Lift scenario it will not be transported in modular form.

What are the key benefits?

A short period of high hot water flow rate
Various Heavy Duty Continuous Flow heater options available
444 Stainless Steel Storage Tanks with 250L and 315L storage volumes
Vitreous Enamel coated tanks with 270L, 330L and 440L storage volumes
Large plumbing connections on storage tanks to cater for high flow rates
Heat source can be located away from the tank to suit installation requirements per project
Modular construction for ease of installation and transport
Perfect for projects with a limited gas supply
External or internal units available
A single HD water heater Demand Duo (DD1) is a stand-alone appliance for ease of installation which is perfect for quick replacements
Single Lift option of the heat source, primary pump(s) and controller(s) for fast site installation
Dual Primary Pump(s) and Control System(s) available in back to back systems
Innovative controller with push button interface and LCD display

What are suitable applications?

Hotels and Motels
Apartment Blocks
Student Accommodation
Variety of other applications where a quick recovery rate is required
Shower Blocks
Commercial Kitchens
Commercial Laundries

Heart of the system

Our Heavy Duty Continuous Flow range of water heaters are specifically designed for commercial use with inbuilt intelligence and durability to stand the test of time in the harshest of commercial environments. With various efficiency and flow rate options available Rinnai can provide the perfect solution based on your application, whether internally or externally mounted. Generally, projects with very high energy costs would benefit from the use of our HD210 higher efficiency condensing technology as the increased capital expenditure is absorbed by the annual energy cost savings.

Heavy Duty Non Condensing (83% Thermal Efficiency)

Heavy Duty Condensing (97% Thermal Efficiency)

Demand Duo Standard Options

How are standard packages supplied?
Demand Duo is available in a wide variety of options to suit your budget. These various forms offer installation flexibility or a complete package resulting in no plumbing or installation work being required. From an integrated Demand Duo with one heater to multiple tanks with multiple heaters there is a solution that can easily be selected to streamline your project.

Integrated Demand Duo 1 gas storage option
Replacement of an existing gas storage heater is made simple with our Demand Duo 1 unit. Lightweight yet robust construction allows for easy transportation into those hard to get to places while offering many years of consistent hot water. Your choice of HD water heater can be integrated with either a vitreous enamel or Stainless steel storage tank offering flexibility of choice to suit all applications and water quality restrictions. The smallest unit available using
a Stainless Steel 250L tank and HD28 weighs in at approximately 100 kgs.

Demand Duo using multiple HD’s

If your project has a large hot water demand where high peak flow rates are expected then selecting a Demand Duo with multiple water heaters is ideal. A modular system using one or more storage tanks will cater for this hot water load. Installation is made easy with our three options under the Demand Duo range available – whether it’s a retrofit project or a complete package you’re looking for we have the solution.

Demand Duo

The tried and tested Demand Duo, that has widely become accepted as the go-to product for centralised hot water systems, is supplied in a modular form being split into 3 major components.
1. Storage Tank(s)
2. Primary activation pump(s) and required fittings
3. Heat source (using the HD water heaters of your choice) with integrated intelligent controller
The heat source is bundled in modules for ease of transportation to the installation site which is ideal for those upgrade projects to replace existing outdated hot water plants.
When working in a tight space, particularly an internal plant room, the flexibility of this Demand Duo system will allow a solution to be designed that could even be installed in stages to minimise interruption to hot water supply.

Demand Duo Plus

As a relatively new addition to the range the Demand Duo Plus is also supplied in modules but in a slightly different format being split into 2 major components reducing on-site installation time.
1. Storage Tank(s)
2. Heat source (using the HD
  Water Heaters of your choice) with integrated intelligent controller and primary activation pump
The heat source is also bundled in modules for ease of transportation but with additional features to save valuable assembly time. The primary activation pump(s) is pre-mounted and appropriately plumbed, including insulation, with the added inclusion of electrical GPO’s for the water heaters and the intelligent controller.

Demand Duo Pro

The Demand Duo Pro is the ultimate hot water package that removes all the worry of assembling modules on site effectively removing all on-site installation time. It is uniquely designed to be sited in position with minimal fuss as all plumbing, insulation and electrical work is provided.
The complete package is engineered to suit your project requirements and mounted on a suitably robust skid base. All you need to do is connect your pipework, plug it in to an electrical outlet and away you go!

Solutions and Accessories

Rinnai can offer a customised solution with a high focus on your core deliverables. The aesthetic appearance of developments is paramount. We can tailor solutions to suit your business, bespoke systems can be constructed to suit specific requirements including (but not limited to) lower frame size, precise wall mounting application or different size pipework. Rinnai’s Commercial Hot Water Solutions match minimum height requirements, are modular and compact, and can be easily integrated into the building, with easy access for future serviceability. To compliment this, we have an extensive range of accessories.

Accessories

315L Horizontal Storage Tank with 32mm plumbing connections
Single circulation pumps for reticulation systems
Dual circulation pumps for reticulation systems with intelligent controller packed with features
Building Management System (BMS) integration
Common flueing for internal installations
Centralised Warm Water Management Valve
Legionella control devices
Heat exchange systems offering flexibility in design of pressure zones or water quality management
Remote monitoring systems to manage your hot water plants from anywhere at anytime
Non-modular packages with engineered frame and lifting points for easy hoisting and placement on site

Tradewinds Cairns | QLD Riley Crystalbrook Resort

Crystalbrook Collection embarked on developing its first five-star hotel, Riley, A Crystalbrook Collection Resort. Located at the northern end of Cairns iconic waterfront Esplanade, the resort features 311 rooms and suites, three restaurants and bars, an expansive lagoon pool and private beach, the Eléme Day Spa and much more.
Rinnai provided two Demand Duo Systems using high efficiency condensing Heavy Duty Water Heaters split over 2 plants. One of which was specifically designed on a low frame to suit the stringent design constraints.

Skye Suites | NSW

A striking new 25-storey high rise, with 73 suites for guests it was designed by the Tokyo-born Sydney architect Koichi Takada. At street level, Arc presents as a handsome 19th-century warehouse, its red-brick columns holding up elegant arches. Twin towers above are topped with arched ribs that look from a distance like white armadillo shells.
Rinnai provided a complex mixture of four Demand Duo systems using Heavy Duty Water Heaters. Common flue was a key feature to minimise the aesthetic impact on the building’s exterior which is often the case with multiple flue terminals.

City West Police Complex | VIC

In a prime location on Spencer Street in Melbourne’s CBD the brief for this brand new state of the art police station was quite specific – construct to exacting security standards but with a 5 star green energy rating.
The internal hot water plant was very specific with two sources of preheated water (to save on fuel costs) and a maximum allowable water temperature to be circulated around the building. Using our Warm Water valve as the basis Rinnai was able to design and construct a complex safety and preheat blending valve system.

Selecting a Demand Duo System

What information do I need?

The following information is required to select a Demand Duo System:
- Delivery temperature required. The available temperatures are 65°C – 82°C in 1°C increments
- Volume of hot water used per event (i.e. people having a shower)
- Number of times this event occurs (i.e. 6 uses of each shower head per hour)
- Internal or external installation (i.e. whether a flue system is required)
A Demand Duo is selected based on the volume of water used per event multiplied by the number of events that occur. This is calculated over a set period of time which is usually one hour.
With our predetermined sizing criteria its never been easier to determine the first hour hot water demand and select the appropriate system.

Apartments

bedroom unit = 45 litres in the first hour
bedroom unit = 75 litres in the first hour
bedroom unit = 105 litres in the first hour

Amenities

Each shower outlet = 27 litres per shower with a maximum of 6 showers per hour
Note: For constant usage showers (sporting clubs as an example) a Rinnai Manifold Pack would be a better option.

Hotel

1 bed in a 1-3 star Hotel = 22 litres in the first hour
1 bed in a 4-5 star Hotel = 35 litres in the first hour
Note: This allows for showers, meals and laundry

Example:
An apartment block in Melbourne consisting of 40 apartments with 2 bedrooms and 10 apartments with 1 bedroom requires hot water at a delivery temperature of 65°C:

Calculate the hot water demand for the 2 bedroom apartments = 40 x 75 litres = 3000 litres
Calculate the hot water demand for the 1 bedroom apartments = 10 x 45 litres = 450 litres
Once you have arrived at the total first hour requirement, 3450 litres in this instance you can select your system
Determine which HD heat source you wish to employ and refer to the tables below to select a system. Using a HD28 external in this example the resulting selection is DD4 28 250

Non condensing HD28 external/internal

Non condensing HD32 external

Condensing HD210 external/internal