Combi vs Heat-Only vs System Boiler: Which Is Right for You?
The secret to a warm, energy-efficient home is choosing the right boiler. Get it right, and you’ll enjoy reliable heating and hot water without paying eye-watering energy bills. Get it wrong, and you could face higher costs, poor efficiency and performance issues.
In this guide, we’ll cover the three main boiler types in a bit more detail: combi, heat only and system.
What is a combi boiler?
A combi boiler does exactly what it says on the tin. It provides a combination of central heating and hot water on demand from a single unit. This means you don’t need to create space for a separate hot water cylinder and cold-water tank.
It works by heating water directly from the mains as you turn on the tap, rather than storing it for later.
Pros
- Compact and space-saving
- Instant hot water
- Lower upfront installation costs
- Simple to maintain
Cons
- Struggles if multiple taps or showers are used at once
- Relies on mains water pressure
- No backup hot water
- Often not compatible with older heating systems
What is a heat-only boiler?
A heat-only boiler, sometimes called a conventional boiler, requires a hot water cylinder and a cold-water tank. It works by heating water from the tank and storing it in the cylinder for later use.
Pros
- Can supply hot water to several taps and showers simultaneously
- Able to handle high hot water demand
- Provides some hot water if the boiler breaks down
- Compatible with solar water heating systems
Cons
- Requires more space
- Need to wait for water to reheat once it’s run out
- Typically more complex and expensive to install
- Higher maintenance demands
What is a system boiler?
System boilers are a hybrid of combi and heat-only boilers. Like a combi, the main components are built into one single unit. However, like a heat-only, you’ll still need a separate hot water cylinder.
This makes system boilers a good option for medium to large homes with higher hot water demands but limited floor space.
Pros
- More compact than a heat-only boiler
- Built-in components mean an easier installation
- Provides consistent pressure (depending on mains supply)
- Compatible with modern heating systems
Cons
- Requires space for a hot water cylinder
- Hot water isn’t instant
- Slightly higher installation costs than a combi
- Not as compact as a combi
Key factors to consider
Now you know the pros and cons of each boiler, let’s run through a few important considerations:
- Household size and hot water demand – Combis work best for small properties with low hot water demands. Heat-only and system boilers are more suitable for larger properties with high hot water demands.
- Number of bathrooms and simultaneous use – If you have two or more bathrooms, you’ll be better off with a heat-only or system boiler.
- Available space – Combis are the most compact, heat only requires the most space and system sits somewhere in-between.
- Energy efficiency and running costs – Combis are the most energy efficient because they heat hot water on demand. Heat-only and system boilers are slightly less efficient because stored water cools over time.
- Future-proofing – If you’re considering adding solar panels or underfloor heating, a system or heat-only boiler is usually the better choice.
Contact us today for help choosing the right boiler
If you’re still not sure which boiler is right for your home, contact our friendly team on 07990755180. Our boiler installation specialists will run through your requirements and identify the best models, taking the guesswork out of choosing.
