Condensing vs Non Condensing Boiler (2024 Guide)

When choosing the right boiler for your home, the debate between condensing and noncondensing boilers can be confusing. The main difference is in their energy efficiency: condensing boilers can be as efficient as 99%, while non-condensing boilers can, at best, be only 75 % efficient. The unit cost difference is so pronounced that switching to a condensing boiler can save you £310 a year on your gas bills and reduce your carbon footprint.

Ready to make the switch? Here are the primary differences so you can choose the best option for your home.

What is the difference between a condensing and a non-condensing boiler?

The only difference, however, is the energy efficiency. The Condensing boilers are far more energy efficient Boilers. On the Other hand, Non-condensing boilers(inefficient Boilers), with less than 75% efficiency, induce a large amount of heat and energy to be wasted while it is functioning in operation, which greatly reduces the system efficiency of the system.

What Is a Condensing Boiler?

Condensing boilers are the newer, energy-saving option. These include a more sophisticated radiator, which captures heat from the combustion gases that would be wasted in older systems. This means that economy boilers can have an efficiency rating of up to 99%, meaning they are incredibly energy efficient.

Condensing boilers are designed to recycle waste heat, one of their main features. As the gases cool down in the boiler, the vapor condenses and releases additional heat to pre-heat the cold water entering the system. This method minimizes the amount of energy that is wasted and saves you valuable dollar signs on gas expenses.

Condensing boilers are also more environmentally friendly and have energy savings. They generate less carbon emissions, thereby decreasing your overall carbon footprint.

What are the different types of condensing boilers?

Combi Boilers
All-in-one units that provide heating and hot water on demand are ideal for smaller homes with limited space.
System Boilers
Work with a separate hot water cylinder, perfect for larger homes or those with higher hot water needs.
Regular Boilers (Conventional Boilers)
Traditional systems can be upgraded to condensing by adding a heat exchanger suitable for homes with existing tanks.
Combi-System Boilers
A hybrid of combi and system boilers, offering both on-demand heating and hot water with a separate cylinder for larger homes.

What Is a Non-Condensing Boiler?

Non-condensing boilers, on the other hand, are older technology. These boilers rely on a single heat exchanger and release significant heat through the flue. This means non-condensing boilers can only achieve about 78% efficiency, wasting around 22% of the heat they generate.

Because they don’t recycle waste heat, these boilers aren’t as efficient and can drive up your heating bills. They tend to emit higher carbon dioxide levels, contributing to a larger carbon footprint. Choosing a Condensing vs Non-Condensing Boiler impacts your energy bills and your home’s carbon footprint.

Differences between Condensing vs Non-Condensing Boilers

Feature	Condensing Boilers	Non-Condensing Boilers
Other Names	High-efficiency boilers	Traditional boilers / Old Inneficient / Conventional boilers
Size	Compact, lightweight	Bulky, heavy
Installation	Wall-mounted, requires a drain	Floor-standing, no drainage required
Venting	PVC, CPVC, PP, SS, or type BH venting material	Uses chimney or conventional flue
Efficiency (AFUE)	Up to 99%	Up to 78%
Annual Energy Savings	Can save up to £310 per year on energy bills	Higher energy costs, less efficient
Carbon Emissions	Lower emissions, around 5.2 tonnes CO2 per year	Higher emissions, around 7.95 tonnes CO2 per year
Heat Recovery	Recycles exhaust gas to preheat incoming water	Heat is lost through the flue, no gas recycling
Maintenance	Requires annual servicing for optimal efficiency	Requires annual servicing, but generally simpler
Lifespan	Typically 12-15 years with proper maintenance	Typically 10-12 years, may need more frequent repairs
Installation Cost	Higher upfront cost but cheaper in the long run	Lower initial cost, but more expensive to operate
Energy Use	Efficient use of energy, less wasted heat	Wastes around 22% of heat through flue
Ideal Use	Best for energy-conscious homeowners seeking savings	Suitable for homes with older heating systems, lower upfront costs

When Should You Replace Your Non-Condensing Boiler?

If your boiler was installed before 2005, it’s likely a non-condensing boiler. These models waste more energy and contribute to higher energy bills. If you’re still using a non-condensing boiler, upgrading to a condensing model is not just a smart move but is also required by law if you’re replacing the unit.

You can explore how to qualify for a Government free boiler scheme to make the switch more affordable.

Condensing boilers typically offer a 10-15-year lifespan, so if your current boiler is approaching this age, it’s a good idea to start looking for an upgrade. The savings on your energy bills will quickly make up for the initial installation cost.

If your boiler is approaching the end of its lifespan, check out our guide on How Often Should You Replace Your Boiler?

What Are the Advantages of Condensing Boilers?

Higher Energy Efficiency
Condensing boilers capture and reuse heat from exhaust gases, reaching up to 99% efficiency. This means they use less fuel than non-condensing models, which helps reduce heating costs.
Lower Energy Bills
With their high efficiency, condensing boilers can save you up to £310 per year on energy bills, making them a cost-effective long-term choice.
Reduced Carbon Emissions
By using less fuel, condensing boilers produce fewer carbon emissions. This makes them a greener option, contributing to a smaller environmental footprint.
Compact Design
Many condensing boilers are wall-mounted and compact, saving valuable space in your home compared to bulkier traditional models.
Long-Term Savings
While they may have a higher upfront cost, the energy savings and lower operating expenses can make condensing boilers more affordable in the long run.

Switching to a condensing boiler offers financial and environmental benefits, making it an excellent choice for energy-conscious homeowners.

Conclusion

Condensing vs Non-Condensing Boiler: Money-saving Guide for Homeowners Condensing boilers recover excess heat from the combustion gases that flow through the system, making them significantly more efficient and requiring less energy to operate, leading to considerable savings over a non-condensing type in the medium-to-long term.

Condensing boilers are the way forward for a whole host of reasons – they cause less impact on the environment and, as a result, become much cheaper in terms of energy in the long run despite a higher installation cost. Switching to a condensing model is a great investment,t too, and a legal requirement in the UK if you’re replacing your old boiler.