Find your new energy-efficient system boiler
A new system boiler from British Gas could improve your home's energy efficiency - and lower your gas bill by up to 22%.
How to get your system boiler quote
Just book a home visit with one of our experts. We'll give you a quote that covers everything you need for installing your new system boiler, including moving it to a new location and any pipework.
Most popular option
Online quote
Get an instant estimate for a new system boiler in minutes. Just answer a few questions about your home and we’ll do the rest.
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Rather speak to an expert face-to-face? Book a free, in-person visit and they’ll find the right one for your home and budget.
What is a system boiler and how do they work?
What is a system boiler?
Like conventional boilers, system boilers need a hot water cylinder. However, unlike conventional boilers, they don’t need a cold water tank, and components like pumps and valves that are separate in conventional boilers are built-in with a system boiler. You might also hear system boilers being called ‘closed vent’ or ‘system sealed’ boilers.
How do system boilers work?
System boilers work in the same way as conventional boilers, it’s just the components are slightly different. Think of them as the modern upgrade to a conventional boiler.
- Cold water from the mains water supply enters the system boiler
- It passes over a heat exchanger, which heats up the water
- Once it reaches the temperature you’ve set on your thermostat, a pump moves the warm water to your radiators
- The hot water stored in the cylinder stays there until it’s needed
- When you turn on your taps or showers, the hot water is pushed out from the cylinder.
What is the difference between system and heat only boilers?
System boilers work in a similar way to conventional or heat-only boilers, except a conventional boiler needs a cold water tank. Heat only boilers can maintain the water pressure using a feed and expansion tank, whereas a system boiler relies on the mains pressure – so if you live in a low water pressure area, then a system boiler may not be right for you.
Are system boilers expensive to run?
If you have a regular routine for using hot water and know how much you’ll need and when, then a system boiler set to your schedule may actually be more cost-effective than other types of boilers. That’s because you’re paying to heat up only the water you need, and then not wasting it.
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Advantages |
Disadvantages |
|---|---|
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Space saving – as many of the components are integrated, |
Pressure problems – as with combi boilers functionality |
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Less worry – there are no components in the attic, so you |
No instant availability – hot water needs to be heated up in advance |
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Quicker install – there are fewer pieces to fit, so it can be |
A limited supply of hot water – once it’s gone, you’ll need to wait while it heats more |
Choose how you want to pay for your new boiler
A range of loan options 2
Up to 3 years interest free (0% APR or up to 10 year 9.9% APR 3) all available at £0 deposit – subject to status.
Or pay in full
Pay just 10% today and the rest after installation.
Why choose British Gas to install a new system boiler for your home
Our A-rated energy efficient boilers can save up to 22% on your gas bills 1.
- A range of loan options 2 (up to 3 years interest free 0% APR or up to 10 year 9.9% APR 3) all available at £0 deposit – subject to status
- 5-year British Gas warranty - with all parts and labour included 4
- Gas Safe certified installation by a Which? Trusted Trader
- System water treatment and system cleanse included
- Waste collection, recycle or disposal included
- Carbon Monoxide Detector and Room Thermostat included
We stock the best new system boiler brands
At British Gas, we partner with top system boiler brands, including Vaillant, Worcester and many more. And we’ll give you impartial advice to help find the best system boiler for your home.
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Frequently Asked Questions
Are system boilers efficient?
All the system boilers we sell at British Gas are A-rated for efficiency. And in general, system boilers are known to have an efficiency rating of 94%, which makes them great for using the majority of its fuel and turning it into heat and hot water for your home, without wasting too much energy.
Do system boilers have a pump?
Yes, it’s what sends hot water around your home. There’s a water pump within system boilers and when you turn the boiler on, the pump quickly delivers hot water to your radiators and taps.
Additional information
Savings based on an electricity price of 24.5 p/kWh and a gas price of 6.29 p/kWh, calculated from a weighted average of projected, current and recent energy price caps. The estimate applies to a semi-detached, gas-heated home upgrading from a D-rated boiler to a new A-rated boiler (with a programmer, room thermostat and thermostatic radiator controls (TRVs)). Actual savings will vary depending on the size and thermal performance of your home.
British Gas acts as a credit broker, not the lender and offers products from a panel of lenders. Payment options are subject to change without notice. British Gas is a trading name of British Gas New Heating Limited (No. 06723244), an appointed representative of British Gas Services Limited (No. 03141243) which is authorised and regulated by the Financial Conduct Authority (Financial Services Register No. 490568). Both companies registered in England and Wales. Registered office: Millstream, Maidenhead Road, Windsor, Berkshire SL4 5GD. Availability of credit depends on status and credit checks. Terms and Exclusions apply.
Representative example for 120 month order: Cash price: £2,503 | Deposit: £0 | Loan amount: £2,503 | Loan period: 10 years | Monthly repayment: £32.36 | Total amount payable: £3,883.20 | APR: 9.9%.
An annual boiler service is needed to keep your warranty valid. Boiler warranties range depending on the model.