Back Boilers Vs. Combi Boilers – 4 Useful Facts

Many older British homes have back boilers, mainly those built between the ‘60s and ‘80s. These older systems require a lot of maintenance, and while they’re generally reliable, you will eventually need to replace it. The question is whether or not you should go with a new back boiler or upgrade to a newer design like a combi boiler.

In the back boiler versus combi boiler debates, there are many factors you need to consider aside from cost, and you should also know the strengths and limitations of each boiler type so you can make the right decision. Let’s take a look at a few facts about combi and back boilers to help you make your choice.

Energy Efficiency

Back Boilers Vs. Combi Boilers - 4 Useful Facts

You should never buy a boiler based on the equipment cost alone. It’s also important that you take the total cost of ownership into account, which includes energy costs. In the back boilers versus combi boilers debate, combi boilers win hands down.

A back boiler maxes out at just below 80% efficiency. Modern combi boilers can approach 100%, which makes them the most efficient types of boilers on the market. This is why replacing a back boiler with combi boilers can pay off in a few years through reduced energy costs, especially if you rely on a hot water system to both heat your home and deliver hot water.


Boiler installation

A new boiler installation may be the best choice if you’re facing a series of costly emergency repairs as the unit approaches its end of life. However, the current system design affects which boilers are a direct replacement or the changes you may need to make to your home to make a new boiler work.

Follow these installation tips by Boiler Central to make that process as smooth as possible. They run down the basics of boiler installation and what you should avoid when installing one. They also explain what type of boilers work better for certain applications, and the limitations of different types of boilers as well.

For example, you may not be able to use modern dishwashers or washing machines with high water pressure that comes from traditional back boilers. Furthermore, you may not want to replace the existing boiler with a small, simple tankless hot water heater, if it can’t provide hot water to more than one room of the house.

Combi boilers are a good choice for replacing back boilers since they require less space and are easy to install. However, they will not be able to heat massive amounts of water as a back boiler could. In this case, something like a system boiler could be a happy compromise.


Combination boilers combine the central heating boiler with a hot water heater in a single compact unit. This eliminates the separate hot and cold-water tanks in back boilers. It may free up space in your home or just eliminate the need to vent fumes through the fireplace.

Combi boilers are a good choice for small homes or flat, too. Switching to a combi boiler could free up space in your water cupboard or current utility room. A lot of people also choose to go for a combi boiler for their country houses as they will usually have less space to work with.

Hot Water Supply versus Demand

Hot water supply

The greatest drawback of combi boilers is their ability to provide hot water for simultaneous use. Traditional boilers fire up twice a day, heating up the water whether you need it or not. While this has the disadvantage of not being energy efficient, it also means that you have a reserve of hot water that can be delivered to multiple taps in the home.

However, combi boilers may not be able to meet your needs if you have two people taking hot showers at the same time. A system boiler may be a better choice in that case. However, combi boilers can meet modest, intermittent demand for hot water.

You should also know that having a tank is not always a benefit when it comes to the water supply. Having a tank also means that your hot water can run out. On the other hand, a combi boiler can do a better job of meeting demand if you’re constantly using some hot water through the day for showers, laundry, and dishes, but do each separately. As a traditional boiler only fires up twice a day, you’ll have to wait for hot water if you use up the current supply. Not only that, but there’s also the possibility to install more than one combi boiler to deal with the simultaneous use issue.

If you are looking to replace a back boiler, combi boilers are probably the best choice. However, you need to take a variety of factors into account in order to select the best boiler for your household’s needs.

There are many factors to consider aside from cost when looking at back boilers Vs combi boilers, like the strengths and limitations of each boiler type.

Leave a comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Previous Post Next Post