Why choose a Dualstream system?
The Dualstream System
The Dualstream systems by GAH Heating Products have been developed as an advanced solution for domestic hot and cold water installations. A Dualstream system will increase the water volume and maintain the mains pressure to both the hot and cold supplies, even when more than one outlet is in use at the same time. Dualstream has been designed to function on the minimum standard for domestic water supply as provided by local water authorities - which is 1 Bar at 9 litres per minute. GAH offer full technical assistance and design service to enable the optimum Dualstream system to be configured to overcome situations where poor mains supply and pressure are considered a problem.
How the Dualstream system works
The system mainly comprises:- an unvented direct or indirect cylinder, an accumulator (cold water storage vessel), a combination valve and an expansion relief valve. The accumulator has an internal controlled butyl diaphragm, incoming cold water is stored within this diaphragm at mains pressure. The air space between the diaphragm and the accumulator case is pressurised, this balances the supply and maintains pressure to the unvented hot water cylinder and cold outlets. When hot and cold water outlets are turned on the stored water from the accumulator supplements water from the incoming main, this results in consistent pressure and flow to all taps, showers and baths even when outlets are used simultaneously. Pressure will be sustained for as long as the accumulator is holding suffficient volume of water.
The code number refers to the cylinder sizes TDD 200-125 (Model code TDD = Direct), 200 litre accumulator followed by 125 litre hot water cylinder.
Storage Capacity (litres)
inlet/outlet size (inches)
Coil Surface (m² )
Coil Rating (kW)
Reheat Time ( T=50° C)
Dimensions in mm
Weight full (kg)
It is essential that you make the correct choice of water cylinder for your needs.
Fitting a larger cylinder than is needed leads to a waste of energy as more heat is used to raise the temperature of a volume of water than should actually be needed. This obviously results in higher bills than necessary, wasting money and contributing to the destruction of the environment.
The installation of a cylinder too small for the task, as well as wasting energy, would be extremely frustrating for the members of the household, as the hot water would run out after only a short period of use, perhaps enough for a single bath or shower, and would take a considerable amount of time to reheat, until when only cold water would be available.
To help you avoid these pitfalls, we've provided an easy-to-use hot water cylinder size calculator. All you have to do is answer a few simple questions and the calculator will provide you with the approximate size of cylinder you should be looking at.
Once you know the size you need, click on the link which will take you directly to our online shopping site where you can browse through our huge range of cylinders at amazing prices! You're certain to find exactly what you're looking for.
Note: Although every attempt has been made to ensure accuracy, these calculations are for guidance only and Hot-Water-Cylinders.com accept no responsibility for any results provided.
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