[Local Govt News (February) Heating Controls - Cleaner, Greener, Cheaper]
During the past few years domestic boiler controls have improved significantly in their ability to efficiently manage the provision of heating and hot water. In fact Buderus estimate the difference between the traditional on/off operation and room temperature modulation can be over 5%. This can result in considerably lower emissions and fuel consumption, and ultimately means tenants and home owners getting more heat for their money every year. For example the use of best practice controls on an old existing gas boiler which previously had no controls at all can save around 18%. This is recognised as VAT charged on controls is currently only at 5% to encourage the uptake of energy saving measures.
All too often it is the initial outlay cost of the heating system which determines the purchasing decision rather than whole life costs. As a result, the efficiencies of a SEDBUK A rated boiler are not optimised if it is to be installed with less sophisticated controls. Therfore what may seem like a cost saving initially can, over the life of the heating system, turn into false economy when fuel consumption and servicing costs are taken into account.
Buderus controls are designed to maximise the efficiencies built into their boilers, which are all SEDBUK A rated. Using controls designed to work in harmony with the boiler technology ensures maximum efficiency.
Room temperature modulation for instance, is a relatively new innovation for the UK which further improves efficiency. With a standard modulating boiler using on/off controls, burner output is modulated or automatically adjusted, according to the temperature of the return water. Buderus room temperature modulation controls measure the specific room temperature every few seconds and relay this information via radio frequency back to the boiler. This process is faster and more efficient, as small temperature fluctuations are immediately detected and so less gas is used to restore the temperature to the desired level. This in turn means that the temperature differential between flow and return is more favourable and so the boiler can remain in condensing mode for longer. Comfort levels are also improved as the controls help to smooth out the fluctuations from above and below the temperature set points.
The more ‘intelligent’ the controls, the more the boiler can modulate to operate with additional efficiency. Simple on/off controls require the boiler to come into operation as soon as the temperature falls to a minimum setting and the burner to fire until the upper temperature setting is achieved. This means that the boiler has to come into operation frequently throughout the time-programmed period. Figure A illustrates the temperature fluctuation and firing cycle for a simple on/off boiler.
Flow temperature modulation smoothes out the peaks and troughs of temperature and also reduces burner output gradually as return water flow temperature nears its set level. However flow temperature modulation still involves repeated burner firing as can be seen on Figure B.
Room temperature modulation is one of the latest developments in UK heating technology, providing a much more consistent temperature and a more controlled level of burner operation (see Figure C).
Room temperature modulation offers higher comfort levels because the difference between the required temperature and the actual room temperature is reduced to a minimum. The difference between water flow temperature and room temperature is also lower with a result that there are fewer ‘layers’ of heat within the room and therefore a more consistent and comfortable environment.
It’s easy to presume that the sophisticated technology make these types of control over-complicated and confusing. However they do not have to be. The Buderus ModuLink is a combined single or twin channel timer with built in thermostat which is wireless, enabling the user to simply increase or decrease room temperature from the comfort of their armchair or anywhere else in fact as a controller can be taken into whichever room is occupied at the time and operates up to 30 metres away from the boiler.
Being wireless it is very easy to fit for the installer as it does not require any hard wiring, so there is minimum disruption to the tenant or home owner. The receiver operates on extra low voltage and is connected to the boiler by just two wires, eliminating the need for Part P registered electrical installation.
It should also be remembered that, however efficient the system design, regular maintenance is vitally important to retain optimum operating efficiency and, when installing a replacement boiler to an existing system, cleaning, flushing and inhibiting is essential to bring the whole system up to its most efficient from the start.
The continual drive towards lower energy usage targets will inevitably mean that Building Regulations will almost certainly demand further efficiency in heating systems. With condensing boilers already achieving around 90% efficiency, improvements in control systems offer an opportunity to optimise heating system efficiencies and at the same time reducing CO2 and NOx emissions.
Controls hold the key to maximising and even increasing this efficiency.
