May 9, 2021

What is a Condensing Boiler?

Condensing boilers are a type of boiler that was designed to deliver a highly efficient way of heating for people’s homes.

What is a Condensing Boiler?

In 2005, it became law that all new gas boilers installed in domestic properties in the UK must be condensing. Keep reading to find out how a condensing boiler works and how you could benefit from replacing your old inefficient boiler with a new condensing combi.

If you are looking for the best condensing boilers, then we have a full article dedicated to this here which will help you chooses the best.

How Does a Condensing Boiler Work?

Condensing boilers run on gas or oil and are designed to improve energy efficiency. They use condensing technology to make better use of the heat they generate. Whereas in a non-condensing boiler, when gases are burned they are released via the flue into the atmosphere, with a condensing boiler, the hot gases are trapped and recycled back into the system via a heat exchanger. This heat is then used to heat either radiators or water.

Condensing Boilers vs Non-Condensing Boilers

Condensing boilers are significantly more efficient than non-condensing boilers, with the latest models being capable of reaching over 90% efficiency. Non-condensing boilers are only able to achieve between 70-80%. With such high efficiency percentages, condensing boilers are incredibly cost-effective for homeowners. According to the Energy Saving Trust, you could save up to £315 a year by replacing an old gas boiler with a new A-rated condensing boiler. At iHeat, we only install condensing combi boilers. Check out the most energy efficient boilers here.

Condensing boilers are not only great for saving money but they’re also far better for the environment. By burning less fuel, they also help to reduce a home’s carbon emissions, making them a friendlier option for the environment than non-condensing boilers.

Is a Condensing Boiler Safer than a Non-Condensing Boiler?

Condensing boilers take air in from the outside as opposed to taking air from the inside in the way non-condensing boilers do, reducing the risk of anything harmful being sucked into it. Condensing boilers also dispose of the condensed liquid via a pipe connected to the drainage system, lowering the risk of coming into contact with toxic substances.

Is a Condensing Boiler the Same as a Combi Boiler?

People often mistakenly think the two terms are interchangeable, however, they are in fact different. A combi boiler combines a water heating system and a central heating unit into a single body, removing the need for a separate water tank system.

A combi boiler can be a condensing boiler and all combi boilers being sold following 2005 will be condensing due to the introduction of the regulations regarding domestic boilers in April of that year.

The confusion surrounding the two terms is likely because combi boilers began to grow in popularity around the same time condensing boilers became mandatory.

Advantages of a Condensing Boiler

There are a number of advantages of a condensing boiler:

How Long Do Condensing Boilers Last?

The lifespan of a condensing boiler largely depends on the model, build quality and frequency of use. The average condensing combi boiler lasts between 10 - 15 years but with annual boiler services, your boiler could last even longer.

At iHeat, our boilers come with warranties between 7-10 years, so you can rest easy knowing your boiler will last you a long time.

How Much Does a Condensing Boiler Cost?

Again, the cost of a condensing boiler depends on a number of factors such as model, quality, size in kW and any additional features the boiler comes with e.g. digital display, smart technology etc…

When talking about the size of a boiler, we’re often referring to its size in kW output as opposed to its physical dimensions. Different properties require different sized boilers in order to meet their heating and hot water needs. Generally the higher the kW output, the more expensive the boiler. At iHeat, you can get a condensing combi boiler and installation for as little as £1595 or £10.32 a month, 9.9% APR.

What Size Condensing Boiler Do I Need?

The correct size of boiler for your home depends on your demand for hot water and the number of bedrooms, bathrooms and radiators you have. The general rule of thumb is the higher your demand for heat and hot water, the higher the output you’ll require.

The kW outputs are measured differently for each type of boiler, so you should choose the appropriate kW for the type you will be buying.

Combi Boilers

Output in kW Bedrooms Bathrooms Radiators
24-28 1-2 1 Up to 10
28-35 3-4 1-2 Up to 15
35-43 4+ 2+ Up to 20

System Boilers

System boilers heat your central heating system and produce hot water for a water storage cylinder, directly taking the water from the mains as opposed to using a feed and expansion tank like a regular boiler.

Output in kW Bedrooms Bathrooms Radiators
12-15 1-2 1 10
18-24 3-4 1-2 15
30+ 4+ 2+ 20

Regular Boilers

Regular boilers are also known as ‘conventional’ or ‘heat only’ boilers because they don’t provide domestic hot water on demand the same way combi boilers do. They instead store hot water in a cylinder until it needs to be delivered to a tap or shower. One advantage of this is that they can meet a high demand for hot water instantly, making them ideal for properties with multiple bathrooms, though when the water does run out, you'll have to wait for it to fill up again.

Output in kW Bedrooms Bathrooms Radiators
10-18 1-2 1 10
18-26 2-3 2-3 15
27-40 4+ 3+ 20
Cylinder Capacity (Litres) Bedrooms Bathrooms
120-150 1 1
180 2 1
210 3 2
250-300 4 2
300+ 4+ 2+

When Should I Replace My Boiler?

Boilers have an average lifespan of 10-15 years, so as your boiler approaches the end of its lifetime, you may notice a number of issues arising which will likely cost a lot to fix.

Here are some common signs your boiler needs to be replaced:

1. The Energy Efficiency Rating is Lower Than A

All boilers are rated based on their energy efficiency on a scale of A to G- A being the highest possible rating. A is a rating of 90% efficiency, and G is 70% efficiency. Older boiler models are likely to have low-efficiency ratings, meaning you’re spending much more than you need to on fuel bills. A new A-rated combi could save you up to £315 a year in fuel bills, saving you lots of money in the long run.

2. It Takes Too Long To Heat Up

Over time, your boiler will start to wear out, operating less effectively as it once used to. If you find yourself waiting an unusually long time for your home to heat up, this may be a sign your boiler needs replacing.

3. Requiring Repairs Too Often

It is normal for your boiler to require some kind of maintenance from time to time, however, if you find that you are calling out an engineer to check out and repair your boiler more often than you used to then it is time to get a new model installed instead. This will save you money in the long run and ensure that your home is safe for everyone inside.

4. The Cost of Running

Over time, you will likely notice some increases to your home’s energy bills, however if your fuel price is drastically rising, it is usually a sign your boiler is no longer running efficiently and is due for a replacement.

If you think it might be time to replace your old inefficient boiler, why not get a free, fixed quote on a brand new, A-rated condensing combi boiler installed by iHeat today. For more information and advice, check out our other helpful blogs.

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