I say condensing, you say tomato. Condensing boilers, what it actually means, and what they actually do.
A condensing boiler or condenser boiler is a modern type of boiler designed to maximise efficiency by utilising “condensing” technology.
This means that the hot flue gases are recycled by the boiler and can be re-used for further water heating. Clever, huh?
This not only means less carbon dioxide is released into the atmosphere, but less energy is wasted.
This makes them far better for the environment and helps you to save money on your heating bills.
Less CO2,
less damage,
less bills.
At present, all new boilers are condensing boilers. In fact, this has been the case since 2005 when building regulations were amended that effectively banned the installation of non-condensing boilers. This was in response to growing concerns over increasing energy costs and carbon emissions.
In 2018, BoilerPlus legislation was established and all boilers are now required to have a minimum ErP (energy-related products) efficiency of 92% and all installations must have time and temperature controls fitted (if not already present and working).
Additionally, combi boilers require one of four additional requirements in order to be installed, these can include:
Load compensation - the ability of the flow temperature to be modulated based on the room temperature.
Weather compensation - the ability of the flow temperature to be modulated based on the outdoor temperature.
Smart controls - a control that enables optimisation and automation.
PFGHRD (Passive Flue Gas Heat Recovery Device).
How does a condensing boiler work?
In old non-condensing boilers, hot waste flue gases were released outside of the home, which itself wasted a substantial amount of heat and therefore money.
Modern green boilers are condensing boilers and utilise condensing technology to help reduce this heat loss and improve efficiency.
Condensing boilers recover this heat loss by “capturing” the heat from the flue gases, either via a secondary heat exchanger placed before the flue exit, or optimising flow and return temperatures in the main heat exchanger to allow flue gases to hit cooler pipework and transfer energy.
The result is the prevention of energy waste which means you are getting more heat for the same amount of money.
In either method, during the recovery process, the water vapour in the gasses is transformed from a vapour to a liquid, resulting in the process of condensation, hence why they are called “condensing boilers”.
The temperature of the flue gas can fall as much as 80℃ and the heat which would have been wasted in old non-condensing models can be reused.
During this process, as much as two litres of wastewater is generated each hour, which is removed from the boiler via the condensate pipe.
As a result of this heat recovery process, condensing boilers are much more efficient than old non-condensing boilers, resulting in reduced carbon emissions, energy waste and lower heating costs.
Condensing boilers vs non-condensing boilers
As mentioned, condensing boilers take advantage of condensing technology, while non-condensing boilers use a single heat exchanger and a considerable amount of the fuel they use is wasted via the flue gases.
This means that new boilers, all of which are condensing are at least 90% efficient, while non-condensing boilers are only able to achieve an efficiency rating between 70% and 80%.
Condensing = 90%+ efficient. Non-condensing = 70-80% efficient. You do the math.
This means that condensing boilers produce more heat for the same amount of money and so offer more value for money.
In addition, since they burn less fuel, they help reduce your home's carbon emissions, making condensing boilers much greener.
Advantages of condensing boilers
So what are the major advantages of condensing boilers? Here’s a breakdown:
Superior energy efficient
Modern condensing boilers are fitted with some type of heat recovery system that makes them much more efficient than non-condensing boilers.
Put simply, this means they produce more heat from the energy they burn and waste less energy during the process.
Non-condensing boilers could be less than 60% efficient
In fact, non-condensing boilers could be less than 60% efficient and rated as G under the ERP (Energy Related Products Directive) boiler rating system.
Reduce your energy bills
According to the Energy Saving Trust by replacing your old G-rated non-condensing boiler with a modern A-rated condensing boiler you could save as much as £300 a year.
If you combine that with a smart thermostat and thermostatic radiator valves you could save even more.
For illustration, by installing a Nest, you could save up to £75 and 330kg of carbon a year, as a consequence of its adaptable learning schedule.
Reduce Carbon Emissions
New A-rated boilers that are condensing have significantly lower carbon emissions than the non-condensing boilers of yesteryear.
In fact, by trading in your old boiler for a modern combi boiler (all of which are condensing) you could save as much as 1,220 kg of CO2 each year.
Condensing boilers vs combi boilers- read our guide.
Are condensing boilers the same as combi boilers?
Combi boilers and condensing boilers are all ultimately the same thing. In fact, all modern boilers are condensing whether that be a combi boiler, system or regular boiler.
The confusion likely occurred as it was around the same time that combi boilers started to grow in popularity that condensing boilers became mandatory in the UK.
You no longer need to be concerned about avoiding a non-condensing boiler, since Boiler Plus legislation prohibited their sale in the UK back in 2005.
Check out our condensing boiler vs combi boiler for the full rundown.
In the market for a new boiler? Read all about the best combi boilers.
How long do condensing boilers last?
Typically, a new boiler will last between 10 to 15 years, but it all depends on how well the boiler is maintained, the quality of the boiler and its usage.
In order to ensure your boiler lasts as long as possible and runs efficiently, you should get your boiler serviced annually by a registered Gas Safe Engineer.
Bear in mind, that the majority of warranties offered by the boiler manufacturer are valid on the condition that your boiler is serviced each year.
Learn all about the process of installing a new condensing boiler in our guide to combi boiler installation.
Are all new boilers condensing?
Since Boiler Plus legislation was established on the 1st of April 2005, all new boilers are condensing as that’s what the law stipulates.
Related reading:
What size condensing boiler do you need?
Boiler size is measured in kilowatts per hour and essentially the more radiators, bathrooms and hot water demand your home has, the larger the boiler ought to be.
For example, the average-sized 3-bedroom home would typically require a condensing boiler with a power output of 20-30 kW.
Want to know the kW you need for your home? Check out our "what size boiler do I need" guide. Alternatively, you can use our quick boiler finder tool, which will recommend the boiler that is most suitable for your home.
If you live in an average-sized home, see our guide on choosing the best boiler for a 3 bedroom house.
Best small condensing combi boilers:
#1: Viessmann Vitodens 100-W 26kW
#2: Worcester Bosch CDi Compact – 24kW / 30kW
Best large condensing combi boilers:
#1: Viessmann Vitodens 100-W 35kW
#2: Worcester CDi Classic 38kW
Best offensively large, powerful combi boilers:
#1: Worcester CDi Highflow 29kW / 30kW
#2: Viessmann 111-W 25kW / 32 kW
Looking for the best deal on a new, condensing boiler?
If so, get your new condensing combi boiler installed with Heatable, here’s why:
Gas Safe boiler installation within 24 hours
Thousands of happy customers – an average score of 4.9 on Trustpilot (that’s better than the market leader).
Price match guarantee – if you find a cheaper quote, we will match (must be like for like)
Multiple payment options - interest-free available
Up to 12-year warranty on selected boilers
Fixed price guarantee – no hidden costs
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Heat Happy.
