The Pros and Cons of a System Boiler

When you need to upgrade your boiler - whether it’s part of a planned renovation or because your current one has suddenly packed up, you’ll have a lot to think about. Choosing which boiler will replace your current one is not a decision to take lightly, as a new boiler is a long-term investment. As well as choosing a size and brand, you’ll also be considering which type of boiler best suits the needs of your family, and ticks the most boxes in terms of home suitability.


Here at Smart Gas Plumbing & Heating, we know how overwhelming the choice of boilers can be, so have written some guides to help you make sense of your options. In this post we look at system boilers, helping you weigh up their advantages and disadvantages so that you can make an informed decision. 

What is a system boiler?

A system boiler is a modern unit which works alongside a hot water cylinder. System boilers have the capacity to offer a large amount of hot water and can run to multiple hot water sources at once. This means that you can have a shower while someone else has a bath or uses hot water in the kitchen. For this reason, system boilers are often recommended for homes with more than one bathroom and for families who have a fairly high demand of hot water. System boilers do not require a separate hot water tank.

What are the pros of a system boiler?


Here are the main advantages to switching to a system boiler:


  • They work with a hot water cylinder that’s large enough to store plenty of hot water for when you need it.
  • You can programme your boiler to switch on at certain times to provide heat and hot water when you expect to need it.
  • If you have an en suite or extra bathroom, you can run a bath and shower at the same time while still maintaining pressure. 
  • System boilers can work with solar thermal systems so can potentially be energy-efficient.
  • They are a popular choice for those wanting to save on storage or considering a loft conversion, as they don’t need a cold water tank.


What are the cons of a system boiler?

Before you jump straight into your boiler purchase, you should also consider the disadvantages of different boiler types. Here are the main cons of a system boiler:


  • Although they don’t need a tank, you’ll still need to house a large hot water cylinder as well as the separate boiler unit, so a system boiler may not be suitable if your home is small.

  • There is a risk of water waste, from the boiler heating hot water for the time set and it not all being used.

  • If you forget to programme your hot water you’ll face a wait for a shower or bath as it does not heat it instantly.

  • Because of their separate components and size, system boilers are usually not the cheapest on the market.

Alternative boiler options

Your main alternatives to a system boiler are:


Regular boilers


These are also known as conventional or traditional boilers, and work similarly in many ways to a system boiler. They heat water manually or through a timer in the same way, and the hot water is also stored in a cylinder. The boiler unit and cylinder works alongside a cold water tank, usually housed in the loft space, which is the biggest difference between them and a system boiler. Regular boilers are also suitable for bigger homes with multiple bathrooms and occupants.  


Combi boilers


A combi boiler requires just the boiler unit itself, so it is a great space-saving solution. They heat water directly as you need it, so there is no need to programme your hot water through a timer. This can also make them very energy-efficient.

A combi boiler’s main disadvantage is that they can only send water to a single source. This means that you can’t run a shower at the same time as a hot water tap so don’t usually suit homes with more than one bathroom. 

Trusted boiler installation and advice in West Yorkshire


If you’re considering having a new boiler installed, let the friendly team at Smart Gas Plumbing & Heating help. We have expert boiler know-how and are Gas Safe registered. For safe, reliable and professional boiler installation services, you can count on us. We work in homes throughout Heckmondwike, Batley, Cleckheaton, Dewsbury and Mirfield, and are happy to offer advice on the best boiler for your needs. To find out more you call us on 07900417080, by email at info@smartgasheating.com or send us a message through our online contact form.