What is a Condensing Boiler?

In most cases, due to building regulations, new, gas and oil boilers must be condensing models. Therefore, if you are in the market for a new boiler, it is helpful to know exactly what a condensing boiler is and how it works. A condensing boiler gets its name from the modern technology it uses to operate. This technology means the boiler can convert water vapour into heat, allowing it to recover some of the heat that would have been lost. This increases the amount of usable heat they produce, which is why it is common for condensing boilers to have energy efficiency ratings of over 90%.

The sole difference between these two systems is that non-condensing boilers do not possess condensing technology, instead, heat escapes through the flue pipe. Not only is this inefficient process bad for the environment, but it also leads to expensive energy bills, because energy is being wasted.

Instead of working like non-condensing boilers, which release waste gases into the atmosphere, condensing boilers, have a Flue Gas Recovery System. This system includes two heat exchangers, which enables the boiler to make use of the heat, that would have otherwise been lost. Essentially, when the gas is burned, it is recycled back into the system, meaning that the heat can be used as central heating or hot water.

The main talking point surrounding condensing boilers, which pits them above non-condensing boilers, is their efficiency. An old, non-condensing boiler will continue to lose efficiency with age, whereas the condensing technology found in modern boilers, allows them to use energy more productively. The superior energy efficiency rating means that condensing boilers use less fuel to deliver the same level of heating, reducing a property’s carbon footprint and energy bills.

Condensing boilers do not need to be ventilated, which limits the amount of space they take up. This gives you more options when you are deciding where to have your boiler installed.

While non-condensing boilers take air onboard, condensing boilers are sealed systems. The only air they take in comes from outside, through the flue pipe. They also come with additional safety features, like pressure relief valves, which will turn the boiler off in the event of a fault.

Ranging from no heat or hot water to leaking, kettling, low boiler pressure and cold radiators, condensing boilers share similar problems to non-condensing boilers. However, there is one issue, that is unique to condensing boilers. To ensure they function properly, they need a condensate pipe, which allows for acidic water, produced during the condensing process, to be safely disposed of down a drain. Problems arise with the boiler when the condensate pipe becomes blocked or freezes over.

Luckily, there are several ways you can thaw a frozen condensate pipe yourself. You can do this, by pouring hot water over the frozen part of the condensate pipe, or by holding a microwaveable heating pack or warm cloth over the frozen area.