Dedicated, Knowledgeable Team
Every survey and installation is carried out by Improveasy’s Gas Safe-registered engineers and electricians. You always know who’s coming to your home and who’s accountable for the work.
Heat-Only Boiler Installation
Up to 30% of UK households with conventional heating systems are still running on ageing or inefficient boilers, with much higher running costs than a modern equivalent.
At Improveasy, we install heat-only boilers for homeowners across the UK. We’re also a certified installer for British Gas, meaning we carry out boiler installations on their behalf. Our Gas Safe-registered engineers handle everything from survey to sign-off.
What is a Heat Only Boiler?
A heat-only boiler is a gas boiler that heats your central heating system and hot water by working with a separate hot water cylinder and cold-water tank. It differs from a combi boiler, as it doesn’t provide hot water on demand.
It’s part of a three-component system: the boiler, a hot water cylinder (often found in your airing cupboard), and one or two cold water storage tanks (often found in the loft). Because the hot water is stored, the system runs on an open-vented circuit rather than at mains pressure. It can sometimes supply multiple outlets simultaneously, without affecting flow rates.
This type of system is common in homes built before the 1990s. It is often the most practical and cost-effective replacement option when the existing pipework and cylinder are in good condition.
How Does a Heat-Only Boiler Work?
The system works in a continuous, simple cycle that keeps hot water available whenever you need it:
Mains cold water fills the tanks in the loft.
The cold water storage tank supplies the hot water cylinder with water.
The boiler warms the hot water through an internal coil in the cylinder.
A pump circulates the primary water through your radiators.
A feed and expansion tank in the loft maintains water levels in the radiator circuit and manages pressure as the system heats up.
Is a Heat-Only Boiler Right for Your Home?
Heat-only boilers are not the right fit for every property. If your home doesn’t have a cylinder or loft tanks, a combi boiler may be more appropriate. Our engineers can advise during a free survey.
Here’s how to tell if one suits you:
You have a hot water cylinder and a cold-water tank
If your home already has this traditional setup, a like-for-like replacement is usually the simplest, most cost-effective route. No major pipework changes are needed.
Your home has two or more bathrooms
Heat-only boilers with stored hot water can supply multiple outlets at once without a drop in temperature or pressure. This is something combi-boilers can sometimes struggle with.
You’re in an area with low water pressure
Because the system uses an open vented circuit rather than mains pressure, it can work reliably even where incoming water pressure is poor.
Your existing boiler is old or inefficient
A modern A-rated heat-only boiler is significantly more efficient than models from 10-15 years ago. Most homeowners see a noticeable reduction in energy after replacing an old conventional boiler.
You’re being referred by British Gas
If British Gas referred you to Improveasy as an able-to-pay customer, we’ll manage your installation from start to finish within their quality and compliance framework.
What Size Heat-Only Boiler Do I Need?
The right output depends on the number of radiators in your home and the size of your hot water cylinder, not just the number of bedrooms. Getting the sizing right matters: an oversized boiler can cycle on and off frequently, wasting energy and accelerating wear.
We calculate the required output during your survey, so your boiler is sized correctly for your home.
Property Size
Recommended Output
Typical Hot Water Cylinder
Smaller home (up to 10 radiators)
12-18 kW
Up to 120 litres
Mid-size home (10 – 15 radiators)
18-24 kW
120 – 150 litres
Larger home (15+ radiators)
24 kW plus
150+ litres
How our Installation Process Works
Every boiler installation is handled in-house by Improveasy Gas Safe-registered engineers. The process is designed to be low disruption and fully managed from first contact to final handover.
Select an option
1. From Home Survey
2. Boiler Selection
3. Installation
4. Commissioning and sign-off
5. Aftercare
From Home Survey
We visit your property, assess your existing system, check the cylinder and pipework, and confirm the right boiler specification for your home.
Boiler Selection
We recommend the right model and output based on your home’s size, hot water demand and budget. We install leading brands including Worcester Bosch, Valliant, and Ideal.
Installation
Our Gas Safe engineers carry out the full installation.
Commissioning and Sign-off
We test the full system and register your boiler for the manufacturer’s warranty.
Aftercare
We walk you through your new boiler before we leave, and our team is on hand if you have any questions after the work is done
Heat-Only Boiler Costs and Potential Savings
The cost of a heat-only boiler installation depends on the model, the output, and the complexity of your existing system. Below are the indicative ranges: your confirmed price is provided in writing following a free survey.
Installation type
Typical cost range
Estimated annual saving*
Standard replacement (like-for-like)
£2500 - £4000
Up to £350/year
Replacement with system upgrade
£4000 - £6000
Up to £500/year
British Gas referred installation
Confirmed by British Gas
Varies by property
*Savings estimates based on replacing a G-rated boiler with a modern A-rated unit in a typical semi-detached home. Based on data from the Energy Saving Trust.
Finance options are available for private installations, making it easier to spread the cost. Our team will walk you through all the payment options during your survey.
Referred by British Gas?
Improveasy is a certified delivery partner for British Gas. As one of the UK’s largest obligated energy suppliers, British Gas works with a select network of approved installers to carry out boiler installations for its customers. Improveasy ranks as one of these installers.
If you’ve been referred to us as an able-to-pay customer, the process is straightforward. We contact YOU to arrange a survey, confirm the right boiler for your home, and manage the full installation to British Gas’s quality and compliance standards. You deal directly with our engineers throughout.
What being a certified British Gas Installer means for you:
- Installation carried out to British Gas’s quality and compliance standards
- Full project management from survey to sign-off, no chasing between parties
- Gas Safe registered engineers on every job
- Building regulations certificate and boiler warranty registration included.
Why Homeowners Choose Improveasy
Choosing the right installer matters as much as choosing the right boiler. Here’s what sets us apart:
British Gas Certified
We install boilers on behalf of British Gas for customers who are able to pay, a status that reflects our compliance standards, installation quality, and reliability.
Accredited Across the Board
Gas Safe registered, MCS accredited, and TrustMark registered. We hold every certification required to install and commission your heating system to the highest standard.
6,000 Properties Upgraded
Since ECO4 launched, we’ve delivered over 6000 home energy improvement projects across the UK, more than half completed by our in-house team.
Whole Home Capability
Beyond boilers, we install air source heat pumps, solar, insulation measures, and deliver Warm Home Plan retrofit programmes. If your home needs more than just a new boiler, we can help with that too.
Contact us today
Get in touch to discover how our energy solutions can lower your bills and improve your home.
