What Type Of Shower Can You Have With A Combi Boiler?

Looking at upgrading or installing a new shower in your bathroom? Maybe it’s part of a larger bathroom renovation or simply replacing that old leaky shower for a luxurious rain shower spa experience. Whatever the reason, the type of shower you are able to have in your bathroom can depend on the type of boiler you have.

Combination boilers are by far the most popular type of boiler installed in the UK, with over 70% of homes choosing to install a combi boiler. However, not every type of shower will work with a combi boiler.

In this post, I’ll explain what types of showers work best with a combi boiler and which types you need to avoid. So you can narrow down your search for the perfect new shower to suit your combi boiler home.

Let’s get into it!

What Is A Combi Boiler?

First things first, let’s quickly look at what a combi boiler is, as well as some of its benefits.

Short for combination boiler, a combi boiler is different from other types of boilers because it only heats water when you need it instead of storing water after it has already warmed up. When you turn on the flow of water in your shower, cold water will be gradually pulled up through the boiler. Then, it will be heated as it passes through the boiler itself.

There are several main benefits that you will enjoy if you decide to go with a combi boiler. They include:

  • You will never run out of hot water because it will continuously be pulled through the combi boiler as you need it
  • They are typically more cost-effective and energy-efficient, as water is only heated when it is needed, rather than being heated and then stored in a tank
  • A combi boiler will not take up as much space because you don’t need to worry about having a hot water cylinder or a cold water tank, meaning that a combi boiler will work well even in smaller living spaces
  • You will have a lower risk of pipes freezing
  • Because you have fewer pipes, you will not incur as many maintenance bills
  • As you don’t need a hot water cylinder, they typically cost less to install
Combi boiler
Combi Boiler

The Types Of Shower That Work With A Combi Boiler

There are a few types of showers that will work well with a combi boiler. In short, any shower that has a valve that is compatible with the combi boiler will work well with this system.

Other factors considered good practice is to have a hot pipe that is 15mm in diameter, this will be compatible with most combi boilers. Also, to make sure the flow of warm water in your shower is uninterrupted, your combi boiler should be able to heat 10 to 15 L of water per minute. So check the output and performance of your combi boiler.

Below are the main types of shower that will work with a combi boiler:

Thermostatic Mixer Shower

A thermostatic mixer shower uses a thermostat to control the temperature of the water. You simply need to specify what temperature you would like your water to be. Then, your shower should take care of the rest.

The thermostatic valve should be able to compensate for any variations that could take place with the temperature of the shower. That way, you should enjoy a consistent flow of steady hot water for your shower. Even if someone else in the home begins to draw on the warm water supply, the valve in the shower should still be able to compensate for this without harming the pressure or temperature of the water in the shower.

A thermostatic mixer shower is usually the top recommended option for a combi boiler.

Standard Mixer Shower

A standard mixer shower will give you control over the exact mixture of hot and cold water you are using. For example, you can use two separate taps to control the flow of water. Or, you can use a standard handle to set the temperature exactly as you like it.

Your combi boiler will heat the hot water as you draw upon it. Then, you can control the ratio of cold to hot water to set your temperature. Unlike the aforementioned thermostatic mixer, a standard mixer can suffer from interrupted water pressure and changes in temperature.

This shower is easy to use and relatively inexpensive. 

Digital Shower

Many digital showers are specifically designed for use with a combi boiler. A digital shower is one of the more advanced showers available today. This shower comes with a digital thermostat on the shower unit itself. This means you can program your desired showering temperature with the touch of a button.

And, similar to thermostatic mixer showers, digital showers can respond to fluctuations in temperature and pressure. So you don’t freeze or get scolded when someone runs the taps in the kitchens at the same time as your shower.

Some digital showers even have preset options so you can store your own perfect temperature as well as colour-coded displays.

Advanced level of control, however, typically the most expensive type of shower.

Electric Shower

You can use an electric shower with a combi boiler, or any boiler for that matter. An electric shower will heat the water instantly. Cold water will be pulled from the main areas over a heating element on the inside of the shower unit itself. That way, an electric shower will produce hot water regardless of whether your boiler is working well.

As long as the electric shower is receiving electricity, you will enjoy hot water.

Doesn’t rely on your boiler and is generally the least expensive shower option.

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These are the main shower options that you can use with your combi boiler. The thermostatic mixer shower is usually the top choice to pair with a combi boiler because of the heat control and consistent flow.

Consider the benefits and drawbacks of each of these choices before you make a decision on which shower is best for your bathroom and combi boiler.

Which Type Of Shower Will Not Work With A Combi Boiler?

While many shower options work well with a combi boiler, there is one type that you should avoid, power showers.

Power shower pump will not work with a combi boiler
Pump For Power Shower

Power Shower

Power showers are designed to work with low-pressure boiler systems and therefore will not work with a combi boiler, which is a high-pressure system. They include a pump to help increase the water pressure. However, this can over pressurise a combi boiler system and become quite dangerous. This is why power showers are not recommended with combi boilers.

In general, any shower that requires water to be fed from a tank is not going to work with a combi boiler. Simply because a combi boiler does not come with a tank. Because a combi boiler is designed to produce a steady flow of water, you will not be able to combine a combi boiler with a power shower and its pump. This also means that you shouldn’t add a pump to an existing electric shower either if it’s supplied by a combi boiler.

If you would like to use a power shower, then you will need to have a gravity fed/water tank boiler system.

Final Thoughts…

There you have it. Everything you need to know about what type of shower you can have with a combi boiler.

While a thermostatic mixer shower is the recommended choice you have a few other options available. So, depending on your bathroom plumbing circumstances and budget, there’s the perfect shower option for your home with a combi boiler.


Michael R

Michael is a KBB designer from the UK. He's been designing and project managing new Kitchen, Bedroom and Bathroom installations for over eight years now, and before that, he was an electrician and part of a KBB fitting team. He created The Bathroom Blueprint in early 2020.