Do I need a system boiler for a 5 bedroom house?

If you’re living in a larger property, especially one with four or five bedrooms, choosing the right boiler can feel like trying to solve a puzzle with missing pieces. You want good water pressure, reliable heating, and something that won’t leave the whole household queuing for hot showers in the morning. One of the most common questions we hear is: “Do I actually need a system boiler for a 5-bedroom house?”

Let’s break it down properly.

Combi vs System: What’s the Real Difference?

Before you decide what’s best, it helps to understand how each type works.

Combi Boilers

A combi (or combination boiler) heats water directly from the mains whenever you turn on a tap. There’s no water tank and no cylinder taking up space. It’s neat, compact, and ideal for smaller homes or places where only one hot water outlet is used at a time.

Pros:

• No tank or cylinder, so it saves space
• Highly efficient for small to medium homes
• Hot water on demand

Cons:

• Struggles when multiple taps or showers are used at once
• Not ideal for properties with more than one bathroom

System Boilers

A system boiler stores hot water in a cylinder. The boiler itself still takes water from the mains, but the stored hot water means you can run several taps or showers at the same time without the pressure dropping.

Pros:

• Ideal for larger homes with multiple bathrooms
• Consistent flow rate even when several taps are running
• Works well with modern power showers and large bath fillers

Cons:

• Needs space for a hot water cylinder
• Once the stored hot water is used, you need to wait for it to reheat
• So, Is a System Boiler Right for a 5-Bedroom House?

In most cases: yes, a system boiler is the better choice for a 5-bedroom property, especially if you have multiple bathrooms or you’re planning an extension.

Here’s why:

1. High Hot Water Demand

A typical 5-bedroom home usually has at least two bathrooms, often three. Morning routines alone can put serious pressure on a combi. A system boiler with a large cylinder can supply several outlets at the same time without the dreaded cold-water surprise.

2. Better Flow Rates

Combis rely on your mains pressure. If you’re in an area with average or low pressure, you’ll instantly feel it—especially upstairs. System boilers can deliver stronger, more consistent flow, thanks to the stored hot water.

3. Future-Proofing

If you plan on adding an en-suite, a larger shower, or even smart heating zones, a system boiler gives you far more flexibility. Combis can be pushed to their limit quite quickly in a large home.

4. Energy Efficiency

While combis are efficient in smaller spaces, system boilers tend to run more smoothly in larger homes where heat demand is higher. Many modern cylinders are well-insulated too, so heat loss is minimal.

When Might a Combi Still Work?

There are a few rare exceptions. If your 5-bedroom house has:

• Only one bathroom
• Excellent mains water pressure
• No future plans for extra bathrooms

…then a high-output combi might be possible. But even then, you’d be right at the upper limit of what’s practical.

Recommended Boiler Size for a 5-Bedroom Home

For most households of this size, you’ll be looking at:

• System boiler: 30–40kW
• Cylinder: 200–300 litres (depending on the number of bathrooms)

This setup ensures strong performance even during peak times.

FAQ’s