Gas Boiler Types Explained

One of the most frequent questions we receive at WarmZilla HQ is, “What type of gas boiler do I have?” quickly followed by, “What type of boiler do I need?”

Identifying what type of boiler is currently installed in your home is simple. However, choosing the right boiler for your home depends on multiple factors, which include:

• Efficiency of the boiler,
• Number of bathrooms you have,
• Radiator count in the home,
• Insulation quality,
• And flow rate.

Before we select your home’s new boiler type, let’s discuss how to identify your current system.

How To Identify Your Boiler Type

Identifying your home’s boiler is an easy task that everyone can do. For those unsure where to start, let’s begin at step 1.

Step 1: Locate Your Boiler

There are several locations where boilers will most likely be installed:

• In the kitchen
• Utility room
• Inside an airing cupboard
• In a garage
• Or in your property’s loft/attic

Once you’ve located the boiler, it’s time to do some checks.

Step 2: Check For Hot Water Cylinder

Usually, a hot water cylinder is a large, insulated tank that stores hot water. A generalisation about hot water cylinders is they typically live in an airing cupboard.

If you have a hot water cylinder, you likely have a system or a regular (conventional) boiler. Also, if you’ve found an additional tank, it is a clear sign you don’t have a combination boiler.

Step 3: Is There A Cold Water Storage Tank?

A cold water storage tank, usually a cylindrical container made of galvanised metal, is generally located in a loft or attic.

The only type of boiler that requires a cold water tank is a regular boiler. Also, they are usually more common in large older homes.

Step 4: Check The Boiler Size And Display

A dead giveaway to what type of boiler you own is it says so on the unit itself. If you’ve not found a hot water cylinder or cold water storage tank in your search, you most likely have a combi boiler.

Combi boilers also heat water on demand. If you run the hot water tap and find it hot immediately, you have a combi boiler.

If you are unsure, refer to your boiler’s manual or Google the unit’s model number.

Now that you know how to identify what type of boiler you own, let’s talk about the different types.

Different Types Of Boilers

In the UK, there are three common boilers installed in homes, which are:

• Combination (Combi) boiler
• System boiler
• And regular boiler

Each one has its unique advantages and disadvantages. Let’s start with the UK’s most popular type of boiler:

Combi Boilers

Combi boilers are the most compact type of boiler on the market. In 2023, 80% of UK households will have combi boilers.

Combi boilers get their name because they provide heating and hot water directly from the mains, eliminating the need for separate water tanks or cylinders.

Advantages:

• Space-saving: No need for external tanks or cylinders.
• Energy efficiency: Hot water is delivered on demand, reducing energy waste. The facility must also achieve an efficiency rating above 92%.
• Cost-effective: Lower installation and maintenance costs due to fewer components.

Disadvantages:

• Water Pressure: Dependent on mains pressure; simultaneous use of multiple taps can affect performance.
• Not Ideal for Large Homes: They may struggle to supply multiple bathrooms simultaneously.

All boilers must use condensing technology to achieve at least 92% efficiency. This technology recycles exhaust heat to increase temperature.

System Boilers

System Boilers require a hot water storage cylinder but no cold water tank, as they draw water directly from the mains. They are suitable for homes with higher hot water demands.

Advantages:

• Consistent Hot Water: Can supply multiple outlets simultaneously without pressure loss.
• Space-Efficient: No need for a loft-based cold water tank.
• Fast Installation: Many components are built into the boiler, simplifying installation.

Disadvantages:

• Requires Space for Cylinder: The hot water cylinder needs an airing cupboard or similar space.
• Hot Water Storage: Limited by the cylinder’s capacity, it requires reheating time once depleted.

Regular Boilers

Regular Boilers, also known as conventional or heat-only boilers, use a hot water cylinder and a cold water storage tank, typically located in the loft. They are suitable for homes with traditional heating systems.

Advantages:

• High Demand Capability: Can supply hot water to multiple bathrooms simultaneously.
• Compatibility: Works well with older radiator systems that might not handle high pressure.

Disadvantages:

• Space Requirements: Needs space for both a hot water cylinder and a cold water tank.
• Complex Installation: More components mean a more complicated and potentially costly installation.

Now that we’ve gone through the pros and cons of different types of boilers, which type is best for your home?

Which Type of Boiler Do You Need for Your Home?

Choosing the correct boiler type means you’ll have a unit that offers efficient heating, optimal hot water supply, and long-term energy savings.

The ideal boiler for your home depends on several key factors, including the following:

Property Size and Layout

The size and design of your home play a significant role in selecting the right boiler type.

A combi boiler is the best option if you live in a smaller property or apartment. It provides hot water on demand and doesn’t require additional storage tanks, making it perfect for compact spaces.

If you live in a home with three or more people who might need hot water simultaneously, a system boiler with a separate hot water cylinder may be a better choice.

A regular boiler is perfect for larger homes with high heating and hot water demands, especially those with multiple bathrooms.

Number of Radiators

The number of radiators in your home will directly affect the heating power required from your boiler and the type of boiler that is best for you.

A boiler’s power output is measured in kilowatts (kW). The higher the kW rating, the more heat it can provide.

As mentioned, the number of radiators will determine how many kWs your boiler should possess. As a generalisation:

• Up to 10 Radiators: A combi boiler (24–30 kW) is suitable.
• 10–15 Radiators: A combi or system boiler (30–35 kW) works well.
• 15+ Radiators: A system or regular boiler (35 kW+) is recommended for consistent heating across larger spaces.

Combi boilers work best in homes with fewer radiators, while system or regular boilers are better for high-volume heating properties.

Number of Bathrooms

A significant factor when selecting a type of boiler is your hot water demand. Generally, as a guideline:

• One Bathroom: A combi boiler (24–30 kW) is ideal, providing instant hot water without a storage cylinder.
• Two Bathrooms: A larger combi boiler (30–35 kW) or a system boiler is recommended.
• Three or More Bathrooms: Using a system or regular boiler with a hot water cylinder is best to ensure a sufficient hot water supply for multiple people

If you need a cheat sheet, you can review the table below:

However, if you’ve read the content above and are unsure what boiler is in your home, we can still help.

Still Unsure? Let Us Help!

Choosing the correct boiler can feel overwhelming. After all, there’s a lot at stake.

But WarmZilla has made it easy. Our quick and hassle-free online survey will help you find the perfect boiler based on your home size, number of radiators, and hot water needs.

If you need further clarification, speak with one of our call centre professionals.