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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

When Should You Replace Radiators?

20th May, 2026 Advice

When Should You Replace Radiat...

While radiators are considered to be one of the most resilient things you have in your hom...

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What Type of Boiler Do I Have?

20th May, 2026 Advice

What Type of Boiler Do I Have?

Despite over 22 million UK homes having gas central heating, a great deal of homeowners ar...

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What is Central Heating Sludge?

20th May, 2026 Guides

What is Central Heating Sludge...

Sludge in a central heating system is a mix of dirt, rust, and limescale. Over time, these...

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What is Boiler Renting/Subscription?

20th May, 2026 Guides

What is Boiler Renting/Subscri...

Boiler renting, often regarded as a boiler subscription service, has emerged as a vital al...

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What is a Thermocouple?

20th May, 2026 Guides

What is a Thermocouple?

A thermocouple is a critical component in a boiler system. It acts as a safety device, ens...

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What is a Heat Exchanger?

20th May, 2026 Guides

What is a Heat Exchanger?

Heat exchangers are pivotal devices within a boiler system, playing a crucial role in tran...

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What is a CP12 Landlord Gas Safety Certificate?

20th May, 2026 Advice

What is a CP12 Landlord Gas Sa...

If you're a landlord, you may have heard of a CP12 - but what exactly is it? Let us explai...

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What is a Condensing Boiler?

20th May, 2026 Advice

What is a Condensing Boiler?

Condensing boilers are a type of boiler that was designed to deliver a highly efficient wa...

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What Is BTU in Air Conditioning? (And Why It Matters for UK Homes)

20th May, 2026 Guides

What Is BTU in Air Conditionin...

BTU is a measure of cooling power. It tells you how much heat an air conditioner can remov...

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Wall-mounted or floor-standing boiler?

20th May, 2026 Comparisons

Wall-mounted or floor-standing...

Choosing between a wall-mounted and a floor-standing boiler mostly depends on the type of...

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Vokera Boiler Flashing Green Light - How to Fix

20th May, 2026 Guides

Vokera Boiler Flashing Green L...

The green light is part of the boiler's diagnostic system; a flashing signal often points...

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Viessmann Vitodens 100-W Combi Boiler Review

20th May, 2026 Reviews

Viessmann Vitodens 100-W Combi...

This beast of a combi boiler is one of the most sought-after models from Viessmann

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