Are Combi boilers best for showers?

Considering a Combi boiler but unsure if it will give you the type of shower you need? You’ve found the right article. A Combi boiler will deliver a consistent, high pressure, and hot flow of water to your shower, but there are other factors you need to consider to make sure that a Combi is the most suitable boiler type for your home. 

So whether you already have a Combi and have questions around how it works with your shower or you’re looking to upgrade your heating system, read on for everything you need to know about Combi boilers and showers.

What’s a Combi boiler?

Combi boilers are the most common type of boiler in new homes. They’re also a popular upgrade for homeowners replacing heating and hot water systems in older properties, too. At a glance, a Combi is a boiler system that heats water when you need it, rather than storing it in a water tank or cylinder. 

For a full explanation about how Combis work, head to our article: What is a Combi boiler?

How many showers can a Combi boiler power?

A Combi allows you to comfortably power one shower at a time. The boiler takes water straight from the mains to provide your shower with hot water and good pressure. Combis are more suited to smaller homes with a single bath or shower, rather than a property with multiple bathrooms and simultaneous demand for showers and baths. (If that’s your home, a System or Heat Only boiler is probably more suitable.)

Are Combi boilers good for showers? 

As a rule, yes - Combi boilers are ideal for powering a single shower. Before you arrange for your boiler to be installed, check that it’s compatible with your current shower. (No-one wants  a low-pressure shower!) 

If your shower won’t work with the Combi, then you may need to consider a new shower or choose a different type of boiler that also works in your home. For a quick and easy way to select the right boiler for you, use our boiler finder.

Do Combi boilers give good shower pressure? 

One of the biggest advantages of having a Combi is that it provides a high pressure supply of water with a generous flow. Combis take water straight from the mains, using its direct, high pressure to generate the water pressure that then comes out of your shower. They’re a highly efficient boiler, providing both hot water and central heating without the need for a water cylinder. With a Combi, you’ll save space and still get warmth and high-pressure water on demand.

What types of showers can I use with a Combi boiler?

Combi boilers work with a range of different shower models. From thermostatic mixer showers to digital and electric showers, Combi systems provide sufficient hot water without you ever running out of water. 

• Electric showers heat water instantly, pulling cold water from the mains and over an internal heating unit. The shower will be able to produce hot water regardless of whether the boiler is working or not. 

• Thermostatic mixer showers use a thermostat to regulate the water temperature, so you can set the level that you’d like the flow to come out at.

Can you have a power mixer shower with a combi boiler? 

In short, no. Power showers operate with an in-built pump that needs to be connected to a hot water cylinder, which Combis don’t use. If you have low water pressure and are wanting a power shower, you will need to rethink your home's heating and hot water system. 

Can a Combi run two showers or more? 

As a Combi heats water directly from the water mains to provide instant hot water, we wouldn’t recommend them to be used to power more than one shower at a time. Sending water to multiple outlets at a time weakens its pressure and could cause problems with your boiler, and potentially even lead to boiler breakdown. 

Use our Combi boiler size guide to understand the different power ratings of our Combi models and which is best suited to your household.

Why a Combi boiler isn’t the best for simultaneous showers 

In more detail, Combis have a relatively limited flow of hot water, so they’re not as ideal if you need hot, high-pressure water delivering to several showers, baths, or taps at a time. When you turn on a tap or shower with a Combi, the central heating momentarily switches off. This is not usually noticeable, even if you were to run a bath for 10 minutes. However, if you were to turn two or more hot taps on at the same time, you would notice a slight drop in temperature and pressure. 

If you have a large household and use a lot of hot water, you might find that having a heating system that uses a water cylinder or tank is more suitable. Generally, the bigger the household, the bigger the demand on the water supply, and the bigger the chance that multiple taps are turned on at once. 

If you heat a water cylinder up economically, it doesn’t necessarily cost you more to run. Hot water tanks that are used with System boilers can be fitted with an immersion heater, which means you can still get hot water if your boiler breaks. If a Combi stops working, then you won’t have access to hot water. 

We hope you don’t, but if you do find yourself in this situation, our ‘Why is my boiler not working?’ article is a helpful first port of call.

How to upgrade to a Combi boiler

To wrap up, Combi boilers are a great option for powering a shower in a smaller property. Whether you’re looking to upgrade your boiler, understand new boiler costs, or you’re ready to choose a new Combi today, we’ve got you covered. Our tips and articles page is full of advice like this, and our friendly team are always on hand to give you extra support: Get in touch.