Cylinder Replacements vs Combi Boilers: What’s Better for Your Home?

When upgrading your home’s heating system, one of the biggest decisions you’ll face is choosing between a cylinder-based system and a combi boiler. Each has its benefits, and the right choice depends on your home’s size, usage habits, and efficiency goals.

In this guide, we’ll break down the differences, help you understand the pros and cons of both, and offer guidance on which system might suit your property best.

What is a Combi Boiler?

A combi boiler (short for combination boiler) is an all-in-one unit that provides both heating and hot water on demand, without the need for a separate hot water cylinder.

Key Benefits of a Combi Boiler:

• Space Saving: Ideal for smaller homes or flats, as there’s no need for a hot water storage tank or cold water storage in the loft.

• Efficient Hot Water: Delivers hot water instantly and directly from the mains.

• Lower Installation Costs: Fewer components mean easier and cheaper installation.

Combi Boilers Work Best For:

• Homes with 1 bathroom

• Households with low to moderate hot water usage

• Properties with limited storage space

You can learn more about new combi boiler installations we offer here.

What is a Hot Water Cylinder System?

A traditional heating system uses a boiler to heat water, which is then stored in a cylinder for later use. These systems are often found in larger or older homes.

There are two main types:

• Vented Cylinders: Rely on gravity and a cold water tank in the loft.

• Unvented Cylinders: Connected directly to the mains, offering high pressure and better efficiency.

Why Replace Your Hot Water Cylinder?

Over time, cylinders can become inefficient, corrode, or fail to meet the hot water demand of a growing household. A cylinder replacement improves system reliability and hot water performance.

Cylinder Systems Are Best For:

• Homes with multiple bathrooms

• Households with higher hot water demands

• People who prefer baths or use multiple showers at once

They also work well when combined with renewable heating systems, such as solar thermal panels or air source heat pumps, making them ideal for energy-efficient homes in the long term.

Which is More Energy Efficient?

While combi boilers are often praised for their efficiency, the reality depends on usage.

• A combi boiler avoids standby heat loss (the heat lost from stored water in a cylinder).

• However, modern unvented cylinders are highly insulated and, when used correctly, can be just as efficient, especially when integrated with renewable energy sources.

If you're running multiple showers or have peak-time hot water demand, a cylinder system may actually be more efficient than an overworked combi boiler.

Installation and Running Costs

Combi Boiler Installation:

• Faster and generally cheaper to install

• Fewer parts, less disruption

• Lower upfront cost - starting from £1,850 including VAT with Jubo

Cylinder Replacement Cost:

• Higher upfront investment due to additional components (cylinder, pump, valves, etc.)

• Can be cost-effective for larger households

• More complex installation, especially when upgrading from vented to unvented

Need a quote? Request a boiler or cylinder quote in your area here.

What About Water Pressure?

• Combi boilers deliver water at mains pressure - great for powerful showers.

• However, in homes with poor mains pressure, a cylinder system with a booster pump may be more effective.

Don’t guess - it’s best to have your water pressure assessed by a qualified engineer.

The Verdict: Which Should You Choose?

If you live in a smaller home or flat with only one bathroom, a combi boiler is likely your best bet. It’s compact, efficient, and cost-effective to install. Since it heats water on demand, you won’t need to worry about space for a separate cylinder or cold water tank.

On the other hand, if your household has multiple bathrooms or higher hot water demands, such as running two showers at once or filling a bath while the washing machine is on, a cylinder system will serve you better. It stores a large volume of hot water, making it ideal for busy households and larger properties.

When it comes to energy efficiency, combi boilers tend to perform better for homes with moderate usage, as they avoid heat loss from stored water. However, modern unvented cylinders have come a long way in insulation and can be just as efficient, especially when used with renewable technologies like solar panels or air source heat pumps.

Still Unsure? Let Jubo Help

At Jubo Services, we specialise in both combi boiler installations and hot water cylinder replacements. Our qualified engineers are Gas Safe registered and can assess your property to recommend the most efficient and future-proof solution for your home.

From boiler upgrades to full central heating replacements, we offer end-to-end service tailored to your needs.

Ready to take the next step? Get in touch today for expert advice and a no-obligation quote.