Integration with Building Management Systems (BEMS)
Most BMS systems control the various heating / cooling zones etc. by well tested and established methods, such as “weather compensation”, controlling 3 port mixing valves (Variable Temperature circuits). The building dynamics can also be taken into account by specifically controlling “optimisation” of comfort levels in the various zones etc, in the above cases the boiler/burner plant may be simply enabled/ disabled according to the required room temperatures or occupancy times. During these control functions, the burners/boilers are turned on or off irrespective of whether the burners are fully modulating, high/ low or at the correct operating temperature for the best thermal efficiency of the boiler plant.
In some cases the BMS may sequence the boilers according to load requirements, this is normally done via a common system flow or return temperature sensor determining a set point and P.I action to ”cascade” the boilers as and when required. The disadvantage of this type of sequencing is, unless you isolate the boiler hydraulics that are not currently firing, this will cause system hysteresis and temperature dilution of the required flow temperature set point.
The M2G is fully compatible and complementary to all types of BMS/BEMS systems. The M2G is interlocked by fail safe relays, that are connected in series to the burner/boiler control or stat circuit, the BMS is also connected into this circuit via volt free contacts.
The BMS system will give a “call for heat” or enable signal, the M2G will in turn check for boiler demand and the boiler memorised flow and return profile. The M2G adaptive algorithms will ensure that the best firing stage is established for the current load conditions and invoke a “save mode”. The M2G has been designed specifically to overcome and avoid unnecessary “dry cycling” of the boiler operation under low load conditions, such as for “standing losses” etc.
To further complement the operation of BMS with M2G, it is possible to interface the inputs/outputs of the unit, to volt free relays and in this way it would be possible for the BMS system to directly monitor the M2G operations if required.
Building Management Systems control various and well defined strategies for heating, cooling and lighting etc. In many cases the BMS will have a central control and a number of outstations connected to all the required elements of the building facilities.
Building Management System vs. M2G - expelling the myth
In the case of boiler house plant control, the BMS outstation may have direct control on the operation of boilers and pumps etc. To ensure that required comfort and occupancy times are maintained with the maximum fuel efficiency, the boiler/burners will be enabled or disabled, based on bespoke strategies that are written specifically to the customer’s building requirements and boiler plant design during the commissioning process.
The boilers are normally connected to the heating system via common flow and return headers; in this case the BMS will have temperature sensors installed to measure the combined common flow or return from all of the boilers.
The boiler set point temperature will be maintained by the boiler’s own thermostat or temperature control connected directly to the boiler flow pipe work. In most cases, the BMS will turn off or on the boiler/burner based on the combined header temperature set point. The BMS does not measure the direct flow and return temperatures of each individual boiler.
The M2G has two digital temperature sensors to measure and calculate the direct temperature profile of each boiler, thereby establishing if the boiler thermostat is making a false “call for heat” due to standing losses or thermostat inherent hysteresis. The M2G also measures the boiler thermostat’s status via the Opto isolator inputs; this will in turn activate bespoke algorithms and invoke “save” modes for both high and low firing stages of the burners.
The BMS does not:
Measure direct boiler flow/return temperature measurement on each boiler.
Measure the memorised temperature differential of each boiler.
Measure and check thermostat status for “call for heat” and set point “satisfied”.
Directly control the firing stages for high/ low burners.
Give “first firing” modes to ensure the boiler thermostat set point is always maintained.
The BMS can control the boilers and burners in the following ways, some of which are detrimental to the boiler plant:
The control circuit / stat of the boiler may be interrupted via the BMS relays; this will turn off the boiler/burner, irrespective of the burner firing position or direct boiler set point.
Modulating burners can be turned off at high fire, causing thermal shock to the boiler.
It is not untypical for the BMS to isolate the mains electrical supply to the boiler to turn off boiler. This can cause safety issues with the combustion safeguard control functions.
In summary, it is inaccurate to claim that a BMS is an alternative to the control features and benefits of M2G.
M2G is specifically designed to directly optimise and control boiler load and is designed to complement BMS and boiler controls.
Carbon Trust Approved
Approved by the Carbon Trust, it has been extensively researched and stringently tested to ensure that it delivers what it promises: significant savings on commercial fuel bills. In addition to the short term gain of reducing fuel consumption, it also helps to increase boiler life through reduced firing and more effective control with a ROI achievable within 6-24 months in most cases.