What are the pros and cons of a combi boiler?
If you are considering having a combi boiler installed, there are many benefits to this kind of heating system, but some disadvantages too.
Combi boilers (combination boilers) have quickly become one of the most popular types of boilers in the UK thanks to their ability to heat water on demand without the need for a hot water tank. Their name refers to the fact that they can provide both heating and hot water for your home when required.
Summary of topics:
Whether you want to replace your current boiler with a combi or are simply trying to understand what your options are, it’s important to know the pros and cons of a combi boiler system. Each home and family are different, and you probably have your own needs and hot water demands, so whether a combi will work for you will depend on what these are, as well as the size of your home and the number of radiators it has. You can use the pros and cons below to help you decide whether you should change your boiler for a combi system.
Pros of a combi boiler
Below, you can find the top six advantages of a combi boiler:
Very efficient
Compact
Instant hot water that’s always available
Easy to install
Save money on your bills (compared to an old conventional boiler)
No cold water tank.
Read on to find more information about each bullet point.
Very efficient
It’s thought that as much as 77% of your total annual gas use goes towards heating your home. The rest (23%) is used for hot water and to power your other gas appliances (such as fires, hob, oven, etc).
This means that having an energy efficient boiler is extremely important. All new combi boilers that are installed in the UK need to be condensing and will have an efficiency rating of 90 to 94 per cent, so you’ll have a warmer home for less energy.
Compact
Whereas conventional heating systems require a hot water cylinder, and are generally larger in size, combi boilers can be more compact and they don’t require an external water tank. Their smaller size makes them perfect for small spaces, such as lofts, utility rooms or even kitchen cupboards. Some combi boiler systems do allow for a separate hot water tank, which is ideal for use in larger homes or properties with a high demand for hot water.
Instant hot water when you need it
No one wants to run out of hot water and be left in a cold shower, shampoo still in your hair. However, if you have a conventional boiler system, this is a distinct possibility, as it heats as much water as the hot water tank is able to store. Once the tank is full, it is able to keep the water warm for quite a few hours, but the boiler won’t heat any more until the programme comes back on. When the hot water is used up, it won’t be replaced instantly.
A combi boiler system means you never have to run out of hot water again. The need for a tank is removed, and instead the boiler simply heats water as and when you need it. So when you turn on a hot tap or a shower, the boiler will provide enough hot water until you turn the tap off again, meaning you’ll never be left in a cold shower with a headful of shampoo.
Easy to install
Combi boilers generally have fewer external parts than a conventional boiler, including a water tank, so it often makes them easier and cheaper to install. There’s a chance that fewer pipes need to be run to the boiler, meaning reduced disruption in your home too.
Save money on your bills
As previously mentioned, combi boilers are extremely efficient. This means that you’ll be using less gas each month, and therefore could save money on your energy bills.
No cold water tank
Not only do conventional boilers have a hot water cylinder to store the heated water, they may also have a cold feed tank. This is generally located in the loft. The cold tank is filled with water from the mains which supplies the cylinder. As a combi boiler takes in water directly from the mains when it’s needed, there’s no requirement for a cold water tank, saving even more space in your home.
Cons of a combi boiler
While combi boilers have a lot of benefits, there are still some things that they aren’t able to do as well as a conventional system. Some cons of a combi boiler include:
They need good mains pressure
They don’t have an immersion heater
They don’t work with power showers
They don’t let you use multiple showers or taps at the same time (although other combi possibilities are available as mentioned earlier in the article).
They need good mains pressure
Many conventional systems rely on gravity to work effectively. This is why the tank must be located as high up as possible (generally in the loft). However, a combi boiler takes its water directly from the mains. This is fine if your mains supply has good pressure, but if the pressure is poor, you’ll notice a difference in the pressure of your showers and taps, too. Before having a combi boiler installed, it’s a good idea to check your mains pressure. Although check with the installer for ways around this, for example booster pumps.
They don’t have an immersion heater
Unlike conventional boiler systems, combi boilers don’t have an immersion heater. This means that, if your boiler was to break down, there is no backup system so you would be left completely without heating or hot water until the boiler is repaired.
They don’t work with power showers
Many homes in the UK now have power showers that provide more pressure and therefore a nicer showering experience. Their separate pumps are able to push the water through the system at a faster rate. As a combi boiler uses mains pressure, it’s tricky to install a power shower alongside it.
They don’t let you use multiple showers or taps at the same time
This is one reason why larger homes still make use of a conventional boiler system - they allow you to run multiple showers or taps at the same time without a reduction in pressure or fluctuations in temperature.
A combi boiler, however, generally won’t be able to efficiently run multiple showers or taps simultaneously. This may not be the case if you also have a hot water tank installed alongside your combi boiler, which can be a good solution to the problem. Alternatively, some combi boilers, like the Vitodens 111, have a small tank located internally that may also alleviate the problem.
