M1G direct fired hot water control technology

  • Typically reduces energy costs and carbon emissions by 10%
  • Payback typically under 2 years
  • Compatible with all standard Direct Fired Hot Water Heaters
  • 5 year warranty
  • Sabien provides the project management, installation and commissioning at no additional cost
  • Integrates with all Building Management Systems


M1G is a patented intelligent controller specifically designed for all standard Direct Fired Hot Water Heaters. M1G can be retro-fitted to individual Hot Water Heater and seamlessly integrates with existing controls and building management systems (BMS). M1G does not alter the temperature of the stored water and the set point of the Water Heater is unchanged.

Real Time Monitoring and control - instant cost savings

M1G detects when a Water Heater has a real demand to meet or whether it is short cycling (see below for explanation of short cycling). It does this by taking temperature measurements - every second - of the hot water supply (Secondary Circuit, i.e. the hot water leaving the water heater to the taps or point of use), and the cold water supply to the water heater. This data is analysed every 10 seconds.

A gradual decrease in temperature of the hot water supply is recognised by the M1G as ‘standing losses’ and the water heater is prevented from firing unnecessarily i.e. ‘short cycling’. If there is a sharp decrease, i.e. the temperature of the hot water supply falls rapidly, the M1G instantly recognises this as a real demand for hot water and allows the water heater to fire.   


Illustration of a M1G installation


What is short cycling?

Whatever the size and age of the Direct Fired Hot Water Heater, heat will be lost through the heater’s casing and secondary pumped circuit i.e. hot water supply. This is known as ‘standing losses’.

Furthermore, the majority of Direct Fired Hot Water Heaters use single stage firing with an input heating capacity that is far in excess of what is normally required to cope with the current “standing losses”.

Direct Fired Hot Water Heaters fire to heat the water to 55-60oC . Once the temperature has been reached, this is detected by the Hot Water Heater’s thermostat and the Water Heater stops firing.

With the Water Heater now in standby, heat is lost from the heater and secondary circuits so that the stored water temperature cools due to standing losses. As this cooling occurs the Water Heater re-fires to restore the water temperature, even if there is no genuine demand for hot water. This sequence of events can be repeated many times during the course of a day. This unnecessary firing is ‘short cycling’ and it increases an organisation’s energy costs and carbon emissions significantly.  

  • The minimum firing capacity (kW) of the heater exceeds the amount of heat lost.
  • As consequence the heater reaches temperature very quickly and cools down slowly.
  • This is short cycling –which occurs repeatedly to waste energy and money.


The good news is Short Cycling can now be eradicated with M1G

The table below summarises the results of measurement and verification projects within client estates. The projects were completed across different sectors, applications and varying kW rating of Heaters



For more information or a product demonstration please contact us on 0800 082 18 182 Or email reduceco2@sabien-tech.co.uk