What's a condensing boiler and how does it work?

Do you keep hearing the term ‘condensing boiler’, but you’re not sure what it means? Well, you’ve come to the right place to find out!

This blog will explain everything you need to know about what a condensing boiler is, how it works and more.

What is a condensing boiler?

The name ‘condensing’ comes from the way that the boiler operates. Condensing boilers are designed to help improve energy efficiency and are found in most UK households today. Condensing boilers run on gas or oil. They are able to collect the gas generated by burning fuels and use it to heat the cold water entering the system, which helps to save money and reduces your carbon emissions.

Condensing boilers have now been made mandatory to have in UK households. This is because they are not only better for the environment, but they can also help to reduce your energy bills.

What’s the difference between a condensing and a non-condensing boiler?

Non-condensing boilers also referred to as an open vent boiler, typically takes air from inside the room, whereas condensing boilers are fully sealed to ensure heat insulation and take their air from outside. With the latest designs for combi boilers, being sealed reduces the risk of anything being sucked in side your boiler and breaking it.

One of the main differences between a condensing and a non-condensing boiler is the amount of useable heat that is produced.

Another difference is that non-condensing boilers only have one heat exchanger. Those who still have a non-condensing boiler in their homes can often see the waste gases being released from their flue, showing you just how much heat is actually being wasted.

Most condensing boilers have two heat exchangers to increase efficiency. If you would like more information on what a heat exchanger is, we cover this in another blog, so you can head over and read that blog once you’re done reading this.

How does a condensing boiler work?

Your boiler will either be using gas or oil as its primary fuel. This fuel will begin to burn once the boiler is ignited. As this fuel burns, it inputs the heat from the burner into a primary heat exchanger. Hot air travels through this heat exchanger and is held there for as long as possible to bump up the temperature. This heats up your radiators.

This heat also travels through a condensing area, which is a feature that other boilers don’t have. As the heat travels through the condensing areas, it causes droplets of water vapour, which are collected and disposed of via a drain.

Condensing boilers are designed to recover more heat before it is lost. You would expect the heat from an older boiler to reach above 200 degrees celsius, however, newer, condensing boilers, reduce this to around 55 degrees celsius.

How do I know if my boiler is condensing?

If you’re not quite sure what type of boiler you have installed in your home, or whether or not it’s a condensing or non-condensing boiler, there are a few things you can do to check.

Firstly, have a look at your boiler manual. That’s the easiest option.

However, if your boiler manual has gone walkies, then you can check the following:

Check to see when your boiler was installed.
If your boiler was installed after April 2005, then you have a condensing boiler. This is when the new regulations come into place. All boilers manufactured after this time will be condensing boilers.
Check your flue.
Your flue will be located outside of your home, coming out of an exterior wall or your roof. If your boiler has a metal flue, then it’s most likely a non-condensing boiler.
Check your drainpipe.
If you can see steam coming from your flue, and if you have a white plastic pipe leading to a drain, this means you have a condensing boiler.

Once you’ve done these checks, you should know if you have a condensing or non-condensing heating system.

If your boiler is non-condensing; then you may want to consider upgrading. This way you can relax and put your feet up in your warm home during the colder months knowing that your boiler is reliable and efficient.

Looking to buy a new boiler or upgrade to a new condensing boiler? Here at WarmZilla, we offer the Best Price Guarantee. If you find a cheaper boiler, we will beat it by £50!

What's the difference between a combi boiler and condensing boiler?

There are three main boiler types, which are all available as condensing boilers. These include combi boilers, system boilers and regular (heat only) boilers.

Side note: thanks to new laws, all combi boilers that have been manufactured after April 2005 are condensing boilers.

Combi boilers, or combination boilers as many call them, combine both the central heating elements and the water heater in one unit, so that there is no need for any additional hot or cold water tanks, as you would need with a system or regular boiler.

Combi boilers are fed with cold water directly from the mains, this water is then heating in the boiler unit itself and distributed to the radiators and taps around your home.

Combi boilers are ideal for smaller homes with limited space, that have a high demand for quick and instant hot water.

Now, although the two terms (combi and condensing) are sometimes used interchangeably, they are in fact different. However, you can get a condensing combi boiler with the addition of a Flue Gas Heat Recovery System fitted.

If you would like to know more about the best combi boilers to buy in 2021, the best combi boiler brands in 2021, or a more in-depth blog about how combi boilers work, click these links.

Pros & cons of a condensing boiler

Besides being significantly more efficient than a non-condensing boiler, condensing boiler hosts a whole load of other benefits such as:

Help you save money
Due to the energy and heat that is saved and recycled, condensing boilers can help you save money on your energy bills.
Wireless programming
Your thermostat can be controlled wirelessly. They automatically sense the air temperature and alter your heating as needed.
Space-savers
Condensing boilers are designed to be compact that they can be installed neatly inside your standard kitchen cupboard.
Carbon footprint
And, just to reiterate, they have the ability to reduce your carbon footprint thanks to their efficiency ratings of 90%.

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How much do condensing boilers cost?

The price of your condensing boiler can depend on the boiler model you choose, the property type and the property size.

It is important to consider what size boiler you need for your home, as the most expensive models with bigger kW outputs may not be the most suitable for your home. They could be oversized and too powerful, meaning that energy and money will be wasted. If you are unsure what kW boiler you need for your home, we have a blog that covers this.

When it comes to how much a new condensing boiler could save you regarding your energy bills, replacing your old non-condensing boilers with a condensing boiler and improving your heating controls could save you as much as £300 a year!

Are condensing boilers safe and reliable?

Manufactures and done extensive safety checks to ensure that condensing boilers are fit for purpose, so you can be assured that your condensing boiler is safe and reliable.

As a matter of fact, condensing boilers are known for being safer for your home as they are sealed for heat insulations, this means that there is no risk of anything being sucked into the boiler itself. There is also no risk of being exposed to any toxic substances or gases as everything is disposed of through your flue or drainage system.

A myth about condensing boilers is that they may not be as reliable as other boiler types – this certainly isn’t true. All components these days are just as reliable as standard boilers, perhaps even more so. They’re also fully efficient at all times of operation.

How long do condensing boilers last?

How long your condensing boilers last will depend on numerous factors such as its build quality, the boiler model itself and the usage. It is also important that you get your boiler serviced annually. In most cases, your boiler warranty will become void if you do not carry out the correct annual servicing on your boiler.

It is important to ensure that your boiler should be serviced by a registered Gas Safe heating engineer.

Top 3 best condensing boilers on the market

Viessmann Vitodens 200-W

The Viessmann Vitodens 200-W is available as a combi, system and regular boiler.

With an efficiency rating of up to 98%, the Vitoden 200-W is known to be one of, if not the best condensing boilers in the UK. They are built with high-quality internal components, innovative engineering solutions, and weather compensation technology which takes into account the outside temperature and adjusts the temperature inside.

Having been awarded Which? Best Buy status every year since 2018, the Vitodens 200-W also comes highly recommended by the Which? Trusted Traders heating engineers and domestic customers.

Key Features

Up to 98% of the fuel used is converted into heat
Quiet operation thanks to low fan speed
Compact dimensions, only 450 mm wide
Easy to operate Vitotronic control unit with 5-inch colour touchscreen
Control via app and internet (with optional Vitoconnect 100 WLAN adaptor)
Energy efficiency class: A
Optionally available as combi (type BK2B) or system boiler (type B2HB)
System boiler: Cascade with up to six boilers up to 594 kW possible
Environmentally responsible MatriX cylinder burner
Optional remote fault notifications for Viessmann Trained Installers

Worcester Bosch Greenstar 8000 Style

The Worcester Bosch Greenstar 8000 Style is available as both a combi and a system boiler.

Whilst looks aren’t everything, this boiler is the best looking of the bunch, so if your boiler is in a visible area then this big iPad-looking boiler is the one for you. Described by Worcester as the ‘Beautiful Beast’ it certainly lives up to its name. It’s by far the best-looking boiler out there and it’s the most powerful wall-hung boiler on the market.

It’s available in a high-gloss white or black finish and it features a full-colour touchscreen display, making it easier to see and it offers full explanations of any errors without the need to decode the error message in the handbook.

It has all the same great features as the Life range, just with a little added spice. Engineers like it because it’s easy to fit, customers like it because it’s powerful and it looks good and we like it because of all the previous reasons and despite it being fairly early in its lifespan, it’s been a reliable boiler so far and Worcester boilers, in general, are the most reliable.

With an efficiency rating of 94%, we can see why so many people rave about the Worcester Bosch 8000 Style boilers. They are slightly more expensive than other boilers on the market but at worth every penny.

Worcester Bosch have been scored an overall brand score of 79% in the Which? Best Buy 2020 survey and have 4.6 stars out of 5 with over 24k reviews. When looking at these ratings, you know you’re dealing with a well-loved boiler brand.

Key Features

Improved LCD display for ease of use
Easy integration with smart controls
Very quiet boiler
Award-winning customer service
Established brand leaders
10-year guarantee (when purchased through WarmZilla)
A design-led approach makes it the best looking boiler on the market
Intelligent Filling System can regain the correct pressure if it drops for any reason
Compatibility with wireless controls

ATAG iC Economiser Plus

This ATAG boiler is also available as a combi, system and regular boiler.

Although ATAG is a lesser-known brand in the UK, they have been designing and manufacturing boilers for almost 70 years.

With 4.9 stars out of 5 on Trustpilot and over 3.8k reviews, it is clear that customers are satisfied with their ATAG boilers.

The ATAG iC Economiser Plus combi boilers have an efficiency of 94% which is largely down to the quality of components used within the boiler. One of the most important components within this boiler is the iCon heat exchanger, which is made from high-grade stainless steel and has been developed to maintain 98% of its original efficiency levels throughout its lifetime. In addition to the quality of this component, other components within the boiler are made from high-quality stainless steel and brass, as opposed to the plastic components utilised within lesser boilers.

Similarly to the Vitodens 200-W, the ATAG iC Economiser Plus combi boilers also have built-in weather compensation technology, meaning that your boiler can adjust its temperature based on the temperature outside. It is also compatible with Wi-Fi capabilities and can be controlled remotely using a smartphone or tablet.