The importance of removing air from the heating system

System cleansing is widely understood to improve efficiencies. When radiators and pipes are filled with sludge and corrosion the boiler has to work so much harder to reach set room temperature, which wastes a lot of energy. The prevailing wisdom is to fit a magnetic filter, which are great for protecting the boiler on an existing system, but they treat the problems of corrosion and not the cause. Corrosion is caused by air in the system, introduced when for example we ‘top up pressure’ (as we are all encouraged to do). A device about the size and cost of a magnetic filter called a dearator will remove air and prevent corrosion in the first instance.

The importance of a correctly sized boiler

It is common for boilers to be oversized ‘just in case’. Over-sizing however tends to be around 10kW greater than the heat requirement of the property. For example, a standard 3-bed period terrace with double glazing and loft insulation will have a heat requirement of around 6-8kW. Rule of thumb sizing would specify a 15-24kW boiler.

Over-sizing the boiler will lead to it ‘cycling’ on and off. It is the heating equivalent of being stuck in town centre traffic versus cruising along a motorway. Like your car, your boiler will burn more fuel and the components will be put under greater stress, accelerating wear and tear. It will also rarely operate in what is known as ‘condensing mode’ which is when can be 90% efficient. The best guidance we can give is as above: 1) get a boiler with a low minimum output (as per our tables); 2) reduce the maximum output down and 3) pair with a compensation control.