Combi vs Conventional Boilers: Pros and Cons
Comparing the pros and cons of Combi boilers and Conventional boilers will help you to find the most suitable boiler for your home.
Both of these boiler types have some great advantages, that we’ll take you through in this article, but the size of your home, along with your level of demand for heating and hot water, will ultimately be the most significant factor in your decision making.
What is a Combi Boiler?
Before we look at the advantages that Combi boilers have to offer, let’s find out how they work.
Combi boilers are the ultimate space-saver, everything they need is within the unit itself – unlike Conventional and System boilers which require external tanks and cylinders.
By drawing water straight from the mains, Combi boilers are able to provide instant hot water when you need it. So, there’s no need to wait for a hot water cylinder or tank to refill with hot water before you can use it. Instead, turn the hot water tap on and you’ll get hot water.
While this is a massive benefit of Combi boilers, it does have a drawback, as they’re unable to provide a strong supply of hot water to more than 1 tap at a time. So, if you have high demand for heating and hot water, then you might want to consider a Conventional or System boiler.
Combi boilers most commonly run on gas but are also available in oil, LPG or electric.
Combi Boiler Advantages
All Combi boilers installed across the UK need to have an efficiency rating of at least 92%. This means that only 8% of the fuel used by the boiler to generate hot water is wasted, making Combis highly efficient, which leads us onto the next benefit…
Will help to reduce energy bills
Thanks to being highly efficient, installing a Combi boiler will help to reduce your energy bills. Replacing a boiler with an efficiency of 70% with a modern condensing Combi boiler could help to lower your energy bills by £305.
Thanks to their compact size, Combi boilers can fit within a kitchen cupboard, out of sight and out of mind. Perfect for smaller homes that don’t have much space to spare.
As everything a Combi needs is within the unit, and there’s no need for any additional tanks or cylinders, they’re relatively quick and easy to install. Helping to save you time and money on the installation. Plus, they can be installed just about anywhere around a property.
Instant hot water
By storing hot water in a cylinder or tank, Conventional and System boilers are using up energy keeping it warm. Combi boilers provide hot water on demand which means that you’ll be saving energy and keeping those energy bills down. You also won’t run out of hot water.
What is a Conventional Boiler?
Conventional boilers have many names, you might also hear them referred to as Heat-Only, Regular or Traditional boilers. Conventional boilers are the oldest type of boiler on the market but they’ve really advanced over the years to be more reliable and efficient than ever.
Made up of several parts, Conventional boilers require a cold water storage tank in the loft, that fills with water from the mains. This water will travel down to a hot water cylinder, where it’s heated up, ready for when you need hot water.
Also in the loft is a feed and expansion tank, which helps to maintain the correct level of water in the system. This is vitally important because water expands as it’s heated.
In terms of central heating, cold water travels down from the storage tank thanks to gravity. The boiler then ignites and a heat exchanger will increase the temperature of the water and a pump will then get the water to the hot water storage tank. Once you increase the temperature on the thermostat, that hot water will circulate around the radiators.
Conventional Boiler Advantages
If you live in a larger home with a high demand for heating and hot water then you’ll want to consider installing a Conventional boiler. These are the advantages of a Conventional boiler:
Like-for-like boiler replacement is simpler
Replacing a Conventional boiler with a Combi is a complicated process that will require wholesale changes to your heating system. A like-for-like boiler replacement is much simpler, helping to save you time and money.
Can meet higher demands for heating and hot water
If you live in a large home with 2 or more bathrooms, then Conventional, along with System boilers, are the best choices to meet the higher demand for hot water. With the hot water being stored in a cylinder, whether you turn 2 or more taps on they’ll all receive hot water until the cylinder needs refilling.
Combi Boiler Disadvantages
After reading all the advantages of a Combi boiler, it could be easy to jump in and arrange to have one installed but it’s important to weigh out both the pros and cons before making your final decision.
Unsuitable for larger homes
Only being able to provide hot water to a single tap or shower at a time means that Combi boilers aren’t ideal for larger homes with more than 1 bathroom.
Won’t perform well in homes with weak water pressure
To ensure that the water out of your hot water taps is strong, there will need to be a suitable amount from the mains water supply. To increase the strength of the water flow in properties where the mains water pressure is weak, a pump could be installed.
Can’t be installed with old pipework
If you’re looking to replace an old Conventional boiler with a Combi then the existing heating system might not be able to handle the increased mains water pressure. It’s likely that the pipes and radiators will need to be replaced, adding to the installation costs. A like-for-like Combi replacement would be much cheaper.
Conventional Boiler Disadvantages
For homes with a large demand for heating and hot water, you will probably need to consider a Conventional or System boiler. Before going ahead with a Conventional boiler installation, it’s worth knowing the following downsides.
Need a lot of space around the property
With so many external parts, it goes without saying that Conventional boiler will take up a lot of space around your home. For this reason, they’re not the most suitable option for smaller homes that don’t have much space to spare.
No instant access to hot water
Rather than supplying instant hot water when you need it, like a Combi, Conventional boilers store the water in a cylinder which means that when it runs out, you’ll need to wait for it to fill up again.,
As the hot water is stored in a tank or cylinder, the longer it’s there the more heat it will end up losing. To combat this, you’ll need to make sure that it’s well insulated.
Installation could be lengthy and costly
Having to install various parts throughout the property will not only make installation longer but also increase the price.
What is a System Boiler?
As well as Combi and Conventional boilers, there’s a third type of unit that could be ideal for your home: the System boiler.
In terms of how the operate, System boilers are in between Combi and Conventional boilers. They take water from the mains, like a Combi boiler, but then store hot water in a hot water cylinder in the same way as a Conventional boiler, rather than sending it straight to the taps and showers.
|System Boiler Pros||System Boiler Cons|
|Quicker and simpler installation than a Conventional boiler||Take up more space than a Combi|
|Strong water pressure as the water comes from the mains||Hot water won’t be instant|
|Meet high demands for heating and hot water||Cylinder needs to be well insulated to keep the water supply warm|
|Don’t need to install a feed and expansion tank in the loft||The size of the cylinder will determine how much hot water is available at any one time|
Combi vs Conventional Boilers: Which Should You Install?
There are pros and cons to Combi boilers and Conventional boilers but finding the most suitable boiler for your home will come down to your demand for heating and hot water.
For smaller properties with 1 bathroom, a Combi boiler will help to save space, supply instant hot water and help to reduce your energy bills. Everything you could possibly want from a new boiler. However, install a Combi boiler into a larger property with several bathrooms and it will soon become apparent that it isn’t the most suitable unit.
For larger properties, you need a boiler that’s able to provide hot water to more than a single tap or shower at a time and that’s why it would be much more beneficial to install a Conventional boiler.