Guide to Choosing a Water Heater | Great Yarmouth Plumbers

If your boiler is on its last legs or your hot water is not what it used to be, choosing a replacement can feel overwhelming. There are different types of systems, different fuel options, and a wide range of prices. Getting the right setup for your home matters, because a water heating system that is too small will leave you running out of hot water, while one that is oversized will cost more to buy and run than it needs to.

This guide breaks down the main options available to UK homeowners, explains the pros and cons of each, and helps you work out which one is the best fit for your property and household. If you live in Gorleston-on-Sea or anywhere else in the Great Yarmouth area, we can help you make the right choice and handle the installation from start to finish.

Understanding the Main Types of Water Heating Systems

In the UK, there are three main types of system that provide hot water to your taps and radiators. Each works differently and suits different types of property.

1. Combi Boilers

A combination (combi) boiler is the most popular type of boiler in the UK. It heats water directly from the mains when you turn on a hot tap, so there is no need for a separate hot water cylinder or cold water tank in the loft.

How it works: Cold mains water passes through a heat exchanger inside the boiler and is heated instantly. When you turn the tap off, the boiler stops heating.

Best for:

Small to medium-sized homes (up to 3 bedrooms)
Households with 1 bathroom
Properties where space is limited (no cylinder or loft tank needed)
Flats and terraced houses

Advantages:

Compact, saves space
Hot water on demand, no waiting for a cylinder to heat up
Lower installation cost (fewer components)
No risk of the loft tank freezing in winter
More energy efficient than older gravity-fed systems

Disadvantages:

Water pressure and flow rate can drop if multiple taps are used at the same time
Not ideal for homes with more than one bathroom
No stored hot water, so if the boiler breaks down you have no hot water at all
Performance depends on the incoming mains water pressure

Typical cost: GBP 1,800 to GBP 3,500 installed, depending on the brand and output rating.

2. System Boilers

A system boiler works with a separate hot water cylinder (usually in an airing cupboard) but does not need a cold water tank in the loft. The boiler heats water and stores it in the cylinder, ready for when you need it.

How it works: The boiler heats water and sends it to an insulated cylinder where it is stored at temperature. When you open a hot tap, hot water flows from the cylinder. The boiler tops up the cylinder as needed.

Best for:

Medium to large homes (3+ bedrooms)
Households with 2 or more bathrooms
Properties where multiple taps or showers may run at the same time
Homes with higher hot water demand (families with children, for example)

Advantages:

Can supply hot water to multiple taps simultaneously without a drop in performance
Compatible with solar thermal panels (the cylinder can accept heat from solar collectors)
Good water pressure from the mains (no gravity-fed issues)
Stored hot water means you have a reserve even if the boiler is off

Disadvantages:

Needs space for a hot water cylinder
Takes time for the cylinder to reheat once the stored water has been used
Higher installation cost than a combi boiler
The cylinder loses some heat over time, even with good insulation

Typical cost: GBP 2,500 to GBP 4,500 installed, including the cylinder.

3. Regular (Conventional) Boilers with Vented Cylinders

Also called “heat-only” boilers, these work with both a hot water cylinder and a cold water tank in the loft. This is the traditional setup found in many older properties across Norfolk.

How it works: The cold water tank in the loft feeds water by gravity to the hot water cylinder. The boiler heats the water in the cylinder. Hot water pressure depends on the height of the tank above the taps (gravity pressure).

Best for:

Older properties that already have this type of system
Homes with low mains water pressure
Very large properties with high hot water demand

Advantages:

Compatible with existing pipework in older homes (can make replacement easier)
Can supply large volumes of hot water
Works well even with low mains pressure

Disadvantages:

Takes up the most space (boiler, cylinder, and loft tank)
Lower water pressure at taps compared to mains-fed systems
The loft tank can freeze in cold winters (a real risk in Norfolk)
Less energy efficient than modern combi or system setups
Often requires a pump for showers to get decent pressure

Typical cost: GBP 2,000 to GBP 4,000 installed.

Unvented Hot Water Cylinders

An unvented cylinder is a high-performance alternative to the traditional vented cylinder. It connects directly to the mains water supply, so it delivers hot water at mains pressure without needing a loft tank.

Unvented cylinders can be paired with a system boiler, a regular boiler, or even an immersion heater. They are also the standard choice for properties using heat pumps.

Advantages:

Excellent water pressure at every tap and shower
No cold water tank needed in the loft
Compatible with solar thermal panels
Suitable for larger properties with multiple bathrooms

Disadvantages:

Must be installed and serviced by a qualified G3-certified engineer
Higher purchase and installation cost
Needs adequate mains pressure to work properly (at least 1.5 bar)
Takes up more space than a combi boiler (though less than a conventional system with a loft tank)

Typical cost: GBP 1,200 to GBP 2,500 for the cylinder alone, plus installation.

Which System Is Right for Your Home?

The best choice depends on your property and your household’s needs. Here is a simple guide:

Your Situation	Recommended System
1-2 bedroom flat or small house, 1 bathroom	Combi boiler
2-3 bedroom house, 1 bathroom, limited space	Combi boiler
3-4 bedroom house, 2+ bathrooms	System boiler with unvented cylinder
Large house, high hot water demand	System boiler with large unvented cylinder
Older property, existing conventional system, budget upgrade	Regular boiler (like-for-like replacement)
Property with solar panels or heat pump	System boiler or heat pump with unvented cylinder

Things to Consider for Norfolk Properties

Properties in Great Yarmouth and the surrounding area have some specific considerations:

Mains water pressure: Water pressure varies across Norfolk. Some areas have excellent pressure, while others (particularly rural villages) can have lower pressure. If your mains pressure is below 1 bar, a combi boiler or unvented cylinder may not perform well without a booster pump.
Property age: Many homes in the Great Yarmouth borough were built before 1960 and still have their original pipework layout. Switching from a conventional system to a combi can involve significant pipework changes. Sometimes a like-for-like boiler swap is more practical and cost-effective.
Hard water: Norfolk has moderately hard water in many areas. Hard water causes limescale build-up inside boilers and cylinders, which reduces efficiency over time. Consider a scale reducer or water softener to protect your investment.

What About Energy Efficiency?

All new boilers sold in the UK must be condensing boilers, which means they recover heat from the flue gases that older boilers wasted. A modern condensing boiler is typically 90 to 94 percent efficient, compared to 60 to 80 percent for older non-condensing models.

If your current boiler is more than 12 to 15 years old, replacing it with a modern condensing boiler could reduce your gas bills significantly. The Energy Saving Trust estimates that replacing an old G-rated boiler with a new A-rated condensing boiler could save you up to GBP 580 per year on heating bills, though actual savings depend on your home and usage.

Heat Pumps: The Future?

Air source heat pumps are becoming more common in the UK, supported by government grants through the Boiler Upgrade Scheme (which offers GBP 7,500 towards the cost). A heat pump extracts heat from the outside air and uses it to heat water.

Heat pumps work best with underfloor heating or oversized radiators, and they need an unvented hot water cylinder. They are most efficient in well-insulated properties. If your home has solid walls, poor insulation, and small radiators, a heat pump may not be the best option without other improvements first.

We are happy to discuss whether a heat pump would suit your property. It is not the right answer for every home, but for some properties it can be an excellent long-term investment.

How to Choose the Right Size

Boiler output is measured in kilowatts (kW). The right size depends on the number of radiators and bathrooms in your home:

24-27 kW combi: Suitable for small homes with up to 10 radiators and 1 bathroom
28-34 kW combi: Suitable for medium homes with 10-15 radiators and 1-2 bathrooms
35+ kW combi: Suitable for larger homes with 15+ radiators and 2 bathrooms (though a system boiler may be better at this point)
System boilers: Typically 12-25 kW, paired with an appropriately sized cylinder (120-300 litres depending on demand)

Oversizing a boiler wastes energy and money. Undersizing means you will not have enough heat or hot water. A qualified plumber or heating engineer should carry out a heat loss calculation to determine the right size for your property.

What to Look for in an Installer

When choosing someone to install your new water heater or boiler, make sure they are:

Gas Safe registered (for gas boiler installations, this is a legal requirement)
G3 qualified (for unvented hot water cylinder installations)
Experienced with the type of system you are having installed
Willing to provide a written quote with a full breakdown of costs
Offering a warranty on both the product and the installation work

Be wary of quotes that seem unusually cheap. A boiler installation involves gas work, water connections, electrical connections, and often modifications to your flue and pipework. Cutting corners on any of these can be dangerous.

Ready to Discuss Your Options?

Choosing a new water heater is a big decision, and there is no one-size-fits-all answer. The best system for your home depends on the size of your property, how many people live there, your existing pipework, and your budget.

At Great Yarmouth Plumbers, we install all types of boilers and hot water systems. We will visit your property, assess your needs, and give you an honest recommendation with a clear, fixed-price quote. No pressure, no upselling.

Call us on 01493 334000 or send us a message to arrange a free consultation. We cover Great Yarmouth, Gorleston-on-Sea, and all surrounding areas across Norfolk. You can also learn more about our water heater services to see how we can help.