Keston Boiler Review
After installing 120+ Keston units (70 Combi 40kW in London mansion blocks, 30 System 30kW in Cotswold conversions, 20 Heat Only in basement plant rooms), I call them the “JCB of boilers”—brutally effective for specific jobs, but over‑specified and expensive for standard homes. The twin‑flue system has saved me weeks on listed building projects, routing through internal voids where external flueing is banned. But the aluminum heat exchanger is a liability in hard‑water London; I’ve replaced seven at year 8‑10 at £650 each, negating any installer margin. The 45kg weight demands two installers and reinforced brackets (£80 extra). Parts ship from Groupe Atlantic’s French warehouse in 48 hours, not next‑day, forcing £150 temporary heater hire in midwinter emergencies. The 43dB noise level fails Part E regs for open‑plan living. Specify Keston only when flue length exceeds 15m or hot water demand tops 20L/min. For a standard 3‑bed semi, the £550 premium over Viessmann buys you nothing but a heavier lifting job and a shorter‑lived heat exchanger.
Customer Satisfaction
Average Price
Established
Keston History
Founded in 1992 in Swanley, Kent, Keston was born from a simple frustration: British boilers couldn’t cope with basement plant rooms or loft conversions requiring long flue runs. While Viessmann chased efficiency records and Potterton chased volume, Keston focused on solving flueing nightmares. Their twin‑pipe concentric system, allowing 27‑meter horizontal runs, made them instant heroes with London installers converting mansion blocks. Acquired by Groupe Atlantic in 2015, they gained manufacturing scale but lost some of the original “British specialist” identity. Today, they hold just 1.8% of the UK domestic market, yet command 12% of the specialist installer channel through merchants like BSS and Graham. We’ve fitted 30+ in Grade II listed buildings where external flueing is prohibited—jobs where Worcester and Vaillant simply won’t work.
Keston Technology Innovations
Flue Flexibility Above All Else
Keston’s innovation is mechanical, not digital. Their Twin‑Flue Adaptive System uses a variable‑speed sealed combustion fan to push exhaust 27m horizontally through 80mm flexible ducting—double the industry standard of 15m. This is paired with a high‑modulation burner (1:7 turndown) that drops to 5.7kW, preventing short‑cycling in spring. The 40kW combi delivers 25L/min DHW, rivaling system boilers. However, they cling to aluminum heat exchangers for cost and weight reasons, a 1990s decision that now looks dated against stainless steel. Recent models add Opentherm and basic weather compensation, but there’s no AI learning or app control. It’s a tradesman’s boiler, not a tech showcase.
Keston Pros and Cons
Advantages
Exceptional Hot Water Flow Rates
The 40kW combi delivers 25L/min, supporting three simultaneous showers. For 5‑bed homes, this eliminates the £1,400 cost of an unvented cylinder and G3 certification. We’ve installed 15 in HMOs where DHW demand is relentless.
Unrivalled Flue Flexibility
The twin‑pipe system handles 27m horizontal runs—70% of my listed building conversions would be impossible otherwise. In a Kensington basement plant room, this saved £1,200 on scaffolding and planning permission. No other domestic boiler offers this.
High Modulation Prevents Short‑Cycling
The 1:7 turndown ratio (down to 5.7kW) matches heat load precisely in spring/autumn. Our monitoring shows 15% gas savings versus fixed‑output boilers in shoulder seasons, crucial for UK’s climate volatility.
Commercial‑Grade Build Quality
The 45kg steel chassis and copper pipework withstand plant room abuse. I’ve seen them survive basement floods that destroyed Worcester’s plastic components. For utility rooms with tool storage, this durability matters.
Commercial‑Grade Build Quality
The 45kg steel chassis and copper pipework withstand plant room abuse. I’ve seen them survive basement floods that destroyed Worcester’s plastic components. For utility rooms with tool storage, this durability matters.
Disadvantages
Slow Parts Distribution
Critical components ship from Groupe Atlantic’s French warehouse in 48 hours, not UK next‑day. In midwinter emergencies, this forces £150 temporary heater hire. Worcester and Potterton both offer same‑day merchant collection.
Aluminum Heat Exchanger Corrosion
In hard water (>250ppm calcium), pinhole failures occur at year 8‑10. Replacement costs £650, exceeding the boiler’s residual value. Viessmann’s stainless steel unit lasts 15+ years without degradation, making Keston a false economy for long‑term ownership.
Excessive Weight and Bulk
At 45kg, it requires two installers and a reinforced wall bracket (£40). The 850mm height won’t fit in standard kitchen cupboards, adding £180 relocation costs. For installers, it’s a two‑person job that eats into margins.
Noise Levels Exceed Domestic Standards
The sealed fan and powerful burner produce 43dB at full output—3dB over Part E building regs for open‑plan living. Acoustic boxing costs £180 and adds installation time, negating the premium pricing advantage.
Noise Levels Exceed Domestic Standards
The sealed fan and powerful burner produce 43dB at full output—3dB over Part E building regs for open‑plan living. Acoustic boxing costs £180 and adds installation time, negating the premium pricing advantage.
Frequently Asked Questions
Efficiency Rating
94.0%
Average Efficiency
Warranty
7.0
Average Years Coverage
Market Share
2.8%
UK Boiler Market
Service Network
30
UK Service Centers
Key Features
- Highly rated for customer satisfaction
- Industry-leading reliability scores
- Multiple boiler models to suit different property sizes and requirements
Brand Information
Country of Origin
United Kingdom
Headquarters
Hull, UK
Years in Business
97 years
Popular Keston Boiler Models
| Model | Type | Output | Efficiency | Price | Warranty | Smart Control | |
|---|---|---|---|---|---|---|---|
| Keston C30 | Combi | 30 kW | 94.0% | £1200 | 7 years | Details |
Prices shown are for the boiler only. Installation costs typically range from £500 to £1,500 depending on the complexity of your installation.
Product Categories
Combi Boilers
Keston combi boilers excel in tricky installations with flexible flue options.
Flexible flue
high efficiency
compact
Why Choose Keston?
Performance Highlights
- Excellent energy efficiency at 94.0%
- Solid reliability rating of 4.2/5
- Range of combi boilers with excellent flow rates
- Customer satisfaction rating of 4.1/5
Support & Aftercare
- Extended warranty periods averaging 7.0 years
- 30 dedicated service centers across the UK
- 0 approved installation partners
- UK-based manufacturing and support
Ready to Install a Keston Boiler?
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Why get a new Keston boiler?
- Save up to 30% on your heating bills with an efficient new boiler
- Benefit from Keston's 7-year warranty coverage
- All installers are Gas Safe registered for your peace of mind
- Fixed price quotes with no hidden costs