Choose the right boiler
for your London home.
A plain-English guide to boiler types, leading manufacturers, warranties and costs — so you can make an informed decision with confidence, not guesswork.
Gas Safe registered · Brand-accredited installers · Fixed-price quotes
Buying a boiler shouldn’t feel like a gamble.
Most homeowners replace a boiler once every 10–15 years — so it’s no surprise the process feels unfamiliar. The jargon is dense, the brands all claim to be the best, and the price range is wide enough to make anyone nervous.
This guide cuts through the noise. We compare the three boiler types, profile the leading manufacturers sold in the UK, and explain the factors that actually matter — output, warranty, efficiency, parts availability and installation quality — so you can choose with confidence.
RARE has installed and serviced every major brand across Central London for over a decade. This is the same advice we give our own clients.
Three boiler types, explained.
The type of boiler you need is determined by your home’s size, hot water demand and existing system — not by brand preference.
Combi Boiler
Compact, all-in-one — no cylinders or tanks
Typical installed price
£1,800 – £3,500
System Boiler
Stored hot water with a pressurised cylinder
Typical installed price
£2,000 – £4,000
Regular (Heat-only) Boiler
Traditional system with a cold water tank in the loft
Typical installed price
£1,700 – £3,200
Boiler types compared.
| Feature | Combi | System | Regular |
|---|---|---|---|
| Hot water | On demand, unlimited | Stored in cylinder | Stored in cylinder |
| Simultaneous showers | 1 only | 2–3 comfortably | 2–3 with right cylinder |
| Space needed | Minimal (cupboard) | Cylinder cupboard | Loft tank + cylinder |
| Water pressure | Mains-dependent | Strong (mains-fed) | Gravity-fed (lower) |
| Install cost | £1,800–£3,500 | £2,000–£4,000 | £1,700–£3,200 |
| Best for | 1–2 bed flats | 2–3 bath homes | Older gravity systems |
Leading boiler manufacturers.
Not all boilers are created equal. Here’s an honest assessment of the brands we install and service across London.
Vaillant
Germany
Engineered reliability and quiet operation
- Exceptionally quiet operation
- Strong warranty (up to 10 years)
- Excellent aftercare and parts availability
- ecoTEC range is a London favourite
Popular models
ecoTEC 832, ecoTEC 835, ecoTEC Plus
Ideal for
Homeowners who value quiet, reliable performance and strong manufacturer support.
Viessmann
Germany
Cutting-edge efficiency and stainless-steel heat exchangers
- Inox stainless-steel heat exchanger — very durable
- Excellent efficiency ratings
- Smart-ready with ViCare app integration
- Vitodens range is compact and well-built
Popular models
Vitodens 100-W, Vitodens 200-W
Ideal for
Efficiency-focused homeowners who want long-term durability and smart controls.
ATAG
Netherlands
Premium build quality with the longest warranty in class
- Up to 14-year warranty on heat exchanger
- Heavy-duty stainless-steel construction
- Excellent energy efficiency
- Designed for long service life
Popular models
iR24, iC Economiser
Ideal for
Homeowners who want maximum warranty security and premium build quality.
Worcester Bosch
United Kingdom
Britain’s best-known boiler brand — strong local support
- Widely recognised and trusted in the UK
- Excellent parts availability nationwide
- Strong Worcester Bosch accredited installer network
- Good mid-range value
Popular models
Greenstar 4000, Greenstar 8000
Ideal for
Homeowners who want a familiar brand with easy access to parts and service.
Baxi
United Kingdom
Affordable, reliable and straightforward
- Competitive pricing
- Compact designs for tight spaces
- Decent warranty options
- Widely supported by UK engineers
Popular models
800-series, Baxi 600
Ideal for
Value-conscious homeowners who want a reliable, no-frills boiler.
Ideal
United Kingdom
Value-oriented with good warranty support
- Affordable pricing
- Good warranty terms on select models
- Compact and easy to service
- Widely available parts
Popular models
Logic Max, Logic+
Ideal for
Cost-conscious homeowners seeking a balance of price and warranty.
Six things to get right.
The brand matters less than these fundamentals. Get these right and any quality boiler will serve you well for a decade or more.
Correct output (kW) for your home
An oversized boiler short-cycles and wastes energy; an undersized one can’t meet demand. A Gas Safe engineer sizes the boiler to your radiators, pipe runs and hot water needs — not a rule of thumb.
Warranty length and terms
Premium brands offer 7–14 year warranties, but only if the boiler is installed by an accredited installer and serviced annually. Check the small print — some warranties require registration within 30 days.
Efficiency rating
All modern boilers are A-rated (>90% efficient), but some reach 94–98%. Higher efficiency means lower gas bills — typically £200–£400/year savings versus a boiler over 12 years old.
Parts availability and serviceability
A boiler is only as good as the engineer who can fix it. Choose a brand with strong UK parts availability so you’re not left waiting weeks for a component in winter.
Installation quality
A premium boiler installed poorly will underperform a mid-range boiler installed well. Always use a Gas Safe registered, brand-accredited installer who cleans and commissions the system properly.
Total cost of ownership
The sticker price is only part of the picture. Factor in annual servicing, likely repair costs after year 7, efficiency savings, and warranty coverage over a 10–15 year lifespan.
What a premium boiler install costs in London.
Transparent, fixed-price ranges for a fully-managed RARE installation. All prices exclude VAT and materials unless stated — no hidden charges, no surprises.
Combi Boiler
No cylinder — instant hot water
£3,200–£4,200
installed, exc. VAT
- Supply & installation
- System flush & magnetic filter
- Gas Safety certificate
- Smart thermostat included
System Boiler
With hot water cylinder
£4,800–£6,000
installed, exc. VAT
- Supply & installation
- Cylinder supply & fit
- Power flush pre-install
- Full commissioning
Regular Boiler
Traditional gravity system
£4,200–£5,400
installed, exc. VAT
- Supply & installation
- Tank & cylinder install
- System upgrade included
- Building Regs approval
Brand premiums
Premium European brands command higher pricing due to efficiency, warranty and longevity:
ATAG
14-yr heat exchanger warranty
+£1,100
Viessmann
Stainless-steel Inox heat exchanger
+£900
Vaillant
Up to 10-yr warranty
+£600
Worcester Bosch
Strong UK parts network
+£400
Ideal / Glow-worm
Good value, reliable
Baseline
Optional add-ons
Common additions to a standard installation:
System power flush
£650
Magnetic filter (Fernox TF1)
£220
Smart thermostat (Heatmiser / Tado)
£380
New flue route / extension
£480
Gas Safety Certificate (CP12)
£150
Building Regulations sign-off
£200–£400
All prices exclude VAT (20%) and materials unless stated. Members receive 10% off standard rates.
Every install includes Gas Safe certification, warranty registration and a 12-month workmanship guarantee.
Want a tailored estimate? Use our boiler calculator →
Boiler buying — complete topic guide
Combi Boiler Installation
For flats & smaller homes
System Boiler Installation
For larger homes & plant rooms
Hot Water Cylinder Installation
Megaflo, OSO & unvented cylinders
Boiler Installation Costs
Full London pricing guide
Combi vs System Boiler
Which type is right for your home?
Vaillant vs Viessmann
Brand comparison
Boiler Replacement Guide
Repair vs replace explained
Get a Boiler Quote
Fixed price in 3 steps
Heat Loss Calculator
Size your boiler correctly
Boiler Servicing
Annual Gas Safe service
Boiler buying FAQs.
Still unsure? Call us on 020 7458 4949 — we’ll give you honest advice with no pressure to buy.
020 7458 4949Boiler installation calculator.
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Reviewed by RARE Plumbing London Engineering Team
Gas Safe Registered Heating Engineers · Reviewed 28 August 2026