Choosing the right boiler isn’t just about size or budget — it’s about what suits your home, lifestyle, and layout.

At EPM, we install and maintain hundreds of heating systems across Devon, and one of the most common questions we’re asked is:
Should I go for a combi boiler or stick with a heat-only system?

Here’s how they compare — and how to decide what’s right for your property.

What’s the Difference?

Combi Boiler

A combi (combination) boiler provides hot water and heating from one compact unit, without the need for a hot water cylinder or cold water tank.

• Heats water on demand

• Takes up less space

• Ideal for smaller homes and flats

• Common in newer builds and refurbishments

Heat-Only Boiler

Also known as a regular or conventional boiler, it works alongside a hot water cylinder (usually in the airing cupboard) and a separate cold water tank (usually in the loft).

• Better for homes with multiple bathrooms

• Can work with older radiators and pipework

• More suited to larger or traditional properties

5 Questions to Help You Decide

1. How Many Bathrooms Do You Have?

Combis work best for 1-bathroom homes.
If multiple people might be showering at once, a heat-only system with a stored hot water cylinder gives better performance.

2. What’s Your Water Pressure Like?

Combis need decent mains pressure.
Rural properties or older homes with low pressure may benefit from a system with stored hot water.

3. Do You Have Loft or Cylinder Space?

If you're doing a renovation and want to free up space, a combi removes the need for tanks and cylinders.

4. Are You Planning to Extend or Add Bathrooms?

Stored hot water offers more flexibility.
We often recommend a heat-only or system boiler for families planning to expand or future-proof.

5. How Old Is Your Current System?

If you’re replacing an old heat-only boiler, it might be easier (and cheaper) to install a like-for-like.
But if your layout allows, upgrading to a combi could simplify everything.

What About System Boilers?

System boilers sit between the two — they store hot water like a heat-only setup, but don’t require a cold water tank.
They’re a good option when combis aren’t quite enough, but you still want to save some space.

What Does It Cost?

In Devon, typical installations:

• Combi boiler (swap): £1,800–£2,500

• Heat-only boiler (swap): £1,600–£2,200

• Combi conversion (from heat-only): £2,500–£3,500

• System boiler: £2,000–£3,000

All costs include supply, installation, testing, and safe disposal of the old unit. We’ll always provide a clear estimate upfront.

Final Word from EPM

Still unsure which boiler fits your home best? That’s where we come in.
We’ll walk you through the options, explain what suits your property layout, and install it cleanly — with zero fuss and fast turnaround.