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Stephen Day

Gas Safe Engineer at iHeat

Stephen Day is a Gas Safe registered and FGAS certified engineer with over 20 years of hands-on experience in the heating, cooling, and renewable energy industry, specialising in boiler installations, air conditioning, and heat pump systems.

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About Stephen Day

Stephen Day is a Gas Safe registered and FGAS certified engineer with over 20 years of hands-on experience in the heating, cooling and renewable energy industry.

Throughout his career, Stephen has designed, installed and maintained thousands of systems across homes and businesses in the UK. His background on the tools, combined with his directorship role at iHeat, gives him a rare understanding of both the technical and operational sides of the industry.

He has helped to secure Which? Trusted Trader accreditation all with a focus on delivering great service and long-term value for customers. He also writes for the iHeat blog, sharing practical advice and explaining heating topics in plain, helpful language.

Stephen continues to stay up to date with the latest heating technologies, building regulations and low-carbon innovations.

Gas Safe ID: 5910722

Expertise

  • Boiler systems and installation
  • Heat pumps and hybrid heating systems
  • Gas safety and compliance
  • System design
  • Renewable and low-carbon technologies
  • Technical training


Articles by Stephen Day are reviewed by iHeat’s technical team for accuracy and reliability.

Stephen Day's latest articles

Vaillant Comfort Mode (and Flashing C on a Vaillant Boiler)

20th May, 2026 Guides

Vaillant Comfort Mode (and Fla...

Vaillant Comfort Mode is a feature available on Vaillant boilers designed to provide a con...

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Vaillant Combi Boilers

20th May, 2026 Guides

Vaillant Combi Boilers

At iHeat We’ve joined forces with Vaillant UK to become the first online company to instal...

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Vaillant Combi Boiler Costs

20th May, 2026 Guides

Vaillant Combi Boiler Costs

As Vaillant continues to innovate, integrating smart technology and improving energy perfo...

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Vaillant Boiler Red Light

20th May, 2026 Guides

Vaillant Boiler Red Light

Understanding what the red light and associated fault codes mean is vital for boiler owner...

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Vaillant Boiler Parts 2026

20th May, 2026 Guides

Vaillant Boiler Parts 2026

Vaillant boilers use a variety of parts to ensure efficient operation. This section looks...

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Vaillant Boiler Not Working, No Fault Code

20th May, 2026 Guides

Vaillant Boiler Not Working, N...

Boiler error codes provide essential diagnostics for homeowners and engineers alike, signa...

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Vaillant Boiler No Hot Water

20th May, 2026 Guides

Vaillant Boiler No Hot Water

Understanding why a Vaillant boiler fails to provide hot water entails recognising the sig...

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Understanding Boiler kW (Kilowatts) & How To Measure

20th May, 2026 Guides

Understanding Boiler kW (Kilow...

When it comes to choosing a boiler for your home, understanding the concept of kilowatts (...

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Underfloor Heating with a Combi Boiler

20th May, 2026 Guides

Underfloor Heating with a Comb...

Integrating underfloor heating with existing combi boilers can be a practical option for m...

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Why Is My Shower Cold & Not Getting Hot?

20th May, 2026 Advice

Why Is My Shower Cold & Not Ge...

There’s nothing worse than expecting to have a nice warm shower… only to discover your wat...

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Shower Going Hot and Cold - Combi Boiler

20th May, 2026 Guides

Shower Going Hot and Cold - Co...

Within homes across the UK, the combination boiler, commonly known as a combi boiler, serv...

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S Plan Heating System

20th May, 2026 Guides

S Plan Heating System

An S-Plan heating system is a type of central heating system that provides efficient contr...

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