Writing on the BusinessGreen website, Stuart Turner of Hamworthy Heating looks beyond EU legislation on boiler efficiency to discuss how the real energy savings are to be achieved.
Who’s driving energy- efficiency improvements?
ErP [the Energy Related Products Directive] is seen as the driving force for energy-efficiency improvements. The criteria set out in the directive will essentially force the sub-400 kW boiler market to purchase energy-efficient condensing boilers. Good news on the surface. But what the directive fails to recognise is that boilers only achieve these efficiencies if installed, set up and controlled in the most effective way. In other words 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, so typically systems are designed with return temperatures of 30°C or they will only achieve marginally better efficiencies than a high-efficiency non-condensing boiler.”
Let’s compare it to the car industry. The EU’s fuel efficiency and emission reduction standards for new cars, as well as rising fuel costs for consumers, pushed car manufacturers to produce more eco-friendly cars. This put the industry on a level playing field, much the same as ErP will do in our industry. But these environmentally friendly cars will only achieve the stated fuel economies and benefits promised if they are driven correctly and regularly maintained. The variable is us, the driver. 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 boilers. They need to adapt to the 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 boiler system — intelligent controls such as weather compensation and boiler sequence controllers will do that for us.
A 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. This not only saves energy but also ensures even use of the boilers improving life expectancy.
But who’s behind the steering wheel?
Of the sites I have visited this year, more than half had their controls set to ‘on hand’. In other words they are on manual control, requiring user intervention to make changes to the way the system operates.
If a sequence controller was installed in these multiple boiler systems it would enable the boilers to 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 boiler would be operating in its most efficient state — i.e. part-load. This method of operation maintains very high system operating efficiency and prevents wastage of energy or overshooting.
If weather compensation controls are also installed, the system will provides the most comfortable conditions for the occupants of a building, adjusting according to the outside temperatures and allowing boilers to condense whenever suitable system conditions permit — and all this with no human intervention. It would be like driverless cars available to everyone at an affordable price; Google might be there, but the rest of the car industry isn’t ready for that yet!
A lot of this is about education and training on controls and control strategy. If heating systems are installed and set up to the manufacturer’s recommendations, and the building owner or manager has an understanding of how the system operates, massive reductions can be achieved in energy use, gas bills and carbon emissions.
It’s not just about getting it right at the installation stage; just as cars have a yearly service and MOT, boilers need the same.
We cannot fit and forget. Regular service and maintenance will help keep the heating system and boiler working at optimum efficiency and ensure long life. It will also help identify any issues before they result in failure or downtime.
In addition, 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 shouldn’t you do the same for your boiler?
It is vital to keep a watchful eye on the gas consumption of your building so as to be able 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.
In conclusion, the industry needs to take control and go above and beyond legislation to ensure we gain the real benefits that ErP is hoping to achieve.