Dynamic Burner Management Unit
WHAT IS A DBMU?
The Dynamic Burner Management Unit (DBMU) is a unique patented and BRE certified technology that is installed between the thermostat and the burner valve. It alters the firing pattern of the boiler creating fewer but slightly longer burn periods. The overall effect is to reduce the amount of time the boiler is burning.
Typically, a DBMU will save in excess of 16% of fuel consumption however we often see 20% to 25% savings of heating fuel.
On average the units will pay for themselves within 5 to 18 months depending on consumption and in cases of high demands the units’ payback in a shorter period of time than this.
HOW DOES A DBMU WORK?
Fuel consumption is reduced by applying Isaac Newton’s Law of cooling. In layman terms heat gain is twice as fast as heat loss. Therefore, extending the cooling cycle of a boiler by 90% would drop the boiler temperature by around 3 degrees, which would then require a slightly longer burn cycle. This would be increased by around 10-20%.
The net result is that a heating and cooling cycle which would normally take 200 seconds, now takes 320 seconds. If you compare gas consumption over 24 hours, there is no loss in performance to the heating system (Newton’s Law of cooling shows us that) yet gas consumption is considerably reduced.
For example, 8 burns of 10 minutes in a 4-hour period will be typically reduced to 5 burns of 12.5 minutes, i.e. a 21% reduction.
The analogy is that of a car running a lot of short journeys compared with fewer longer journeys, which results in more efficient fuel consumption. The DBMU responds to the needs of the building and there is no variation in internal temperature when a unit is fitted.
IS MY BOILER SUITABLE?
The DBMU is designed to work with nearly all types of gas, oil or dual fuel boilers. The exception to this rule are
steam boilers, which are not suitable as they have no modulation. The DBMU is generally not suitable for wall hung or low water content boilers either, purely on the basis that the return on investment is too long to be financially viable. However, there are a number of newer boilers which are now wall hung to save on space in the plant room which are suitable. We would estimate that 98% of all floor standing boilers and those in excess of 40 kW will be suitable.
COULD INSTALLING A DBMU DAMAGE OR ADVERSELY AFFECT MY BOILER IN ANY WAY?
The DBMU does not alter the way in which your boiler functions, therefore will not damage your boiler in any way, nor will it adversely affect the performance of the boiler. We have never had an issue with units installed in over 10,000 installations.
HOW MUCH MAINTENANCE DO THEY REQUIRE?
None, they require no maintenance whatsoever. You can however, dust them if you want to keep your plant room looking clean and tidy.
CAN'T MY BUILDING MANAGEMENT SYSTEM (BMS) ALREADY DO THIS?
No. The BMS can tell a boiler when to turn on and turn off. It cannot however, alter the firing pattern of the boiler. The DBMU is a patented technology, so any BMS engineer advising you that they can do what the DBMU does is providing false information. We have had numerous instances where a BMS engineer has said that we would not be able to improve on the BMS performance, and every time we have improved on it.
The DBMU will not affect the operation of the Building Management System (BMS), nor will the BMS impact on the DBMU.
HOW CAN THE BMU PROVE ITS SAVINGS?
The DBMU has a short term protocol for identifying the savings being made. The unit runs for 50 cycles measuring the cooling and burning phase for each cycle and takes the average for the 50. It then drops out of circuit and measures the average extension to the cooling times over the 50 cycles.
It can then calculate the difference in the percentage of time the boiler is burning in a cycle and from that determine the savings. It is a test designed to demonstrate the impact of the unit, which aims to extend the cooling curve by the order of 90%. This causes the boiler to cool by up to 3 Degrees C, such that when it refires it burns slightly longer around 10%.
In essence the boiler shuts down for longer without impacting on the delivery of hot water. In addition savings of 16% were identified by the Building Research Establishment certificate CFP 348 on an average winter day of 10 Degrees C. They further identified that at a temp of 0 Degrees C savings of the order of 10% were being made, a significant impact.
As the test takes place over 1 cycle it is not necessary to adjust for all of the issues that arise from a ‘through the meter’ test such as temperature (Degree Days), footfall, night setback, frost stat., BMS changes and the many other things that can affect a long term test. The test is repeated regularly and the results will vary as they are dependent upon the load on the boiler at any one time so they can be very high under light load conditions, or in the single figures if under heavy load. However, each test, which is available on every unit we install, is held on a server which will give a summary of all the boiler savings since installation.
IS THIS NOT THE SAME AS AN ANTI DRY-CYCLING UNIT?
No. All boilers need to dry cycle to a degree to reduce moisture build up. Reducing dry cycling too much will damage your boiler. The DBMU does not alter the dry cycling pattern, it changes the firing pattern of the boiler and as such reduces fuel consumption.
The impact of DBMU Installations
We estimate that the DBMU's installed thus far are saving well over £50,000,000 a year in energy costs.
This equates to a saving of over 4.65 million tonnes of carbon per year.