Who's responsible for driving condensing boiler efficiency?
ErP is the driving force
ErP is seen as the driving force for boiler efficiency improvements. It will essentially force the sub 400kW boiler market to purchase condensing boilers. Good news on the surface. But what the directive fails to recognise is that condensing boilers only achieve these efficiencies if installed, set up and controlled in the most effective way. They need to be installed in a system where they are working in condensing mode (return temperatures need to be at less than 55°C for the boiler to actually start to condense). Otherwise they will only achieve marginally better efficiencies than a high efficiency non-condensing boiler.
Setting up boilers to achieve the efficiencies as stated on paper
Looking at cars, the EU's fuel efficiency and emission reduction standards as well as rising fuel costs for consumers pushed the manufacturers to produce more eco-friendly cars. This put the industry on a level playing field, much the same as the Energy-related Products Directive has done in our industry. But these environmentally friendly cars will only achieve the stated fuel economies and benefits if they are driven correctly and regularly maintained. The variable is us, the driver. In order to achieve the greatest fuel economy in a car, the driver adjusts the throttle and gears at the optimum time and adapts to the changing road conditions (uphill, downhill, weather conditions, etc.).
The same can be said about condensing boilers. They need to adapt to changing load conditions and external influences (weather, building occupancy, etc.). They don’t need to run flat out all the time. Stepping off the gas (modulating the boilers) will save fuel. However we don’t have to be the variable that adjusts the settings in a condensing boiler system due to the availability of intelligent controls such as weather compensation and boiler sequence controllers.
How can we improve heating system efficiency?
Many sites we see have their controls set to ‘on hand’. In other words, they are on manual control, requiring user intervention to change the way the system operates. If a sequence controller was installed, the condensing boilers could be controlled to modulate together to match the load. By firing the maximum number of boilers needed to match the load with each operating at or near its minimum modulation, each condensing boiler would be operating in its most efficient state, i.e. part-load. This maintains very high system operating efficiency and removes wastage of energy.
Add in weather compensation controls and the heating system can adjust accordingly to the outside temperatures to allow the condensing boilers to condense whenever suitable system conditions permit. All this with minimum human intervention, like a driver-assist car. A lot of this is about education and training on controls and control strategy. If commercial heating systems are installed and set up to the manufacturers recommendations, and the building owner or manager has an understanding of how the system operates, they can benefit from massive reductions in their energy use, gas bills and carbon emissions.
A Merley sequence controller installed with modular boilers in this district heating scheme helps to effectively manage the eight boiler modules and share the load in the most efficient way.
Keeping boilers efficient and reliable with regular maintenance and servicing
It’s not just about getting it right at the installation stage, just like cars have a yearly service and MOT, condensing boilers need the same.
Regular service and maintenance will help keep the commercial heating system and boiler working at its optimum efficiency and ensure it has a long life.
The system needs to be monitored to spot any spikes or changes. How many people keep an eye on the number of miles they are getting to the gallon or how much is being spent on fuel for the car? So why wouldn’t you do the same for your boiler? It is vital to keep a watchful eye on gas consumption of your building to notice a change in the way it is operating which could signify a leak or identify a need for change in the current control strategy. It will also enable you to demonstrate a return on investment if you are replacing old boilers in a heating system.
The industry needs to take control and go above and beyond the legislation to ensure we gain the real benefits that the Energy-related Products Directive is hoping to proliferate.