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Stephen Day

Gas Safe Engineer

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.

Expertise & Focus Areas

  • 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

What Temperature Should My Boiler Be Set At In Winter?

30th May, 2025 Guides

What Temperature Should My Boi...

Boilers and central heating systems play a crucial role in keeping homes warm during the c...

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Can a Boiler Lose Pressure Without a Leak?

30th May, 2025 Guides

Can a Boiler Lose Pressure Wit...

Boiler pressure refers to the force with which hot water moves through a central heating s...

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Top 5 Reasons Your Thermostat Isn’t Working Properly

30th May, 2025 Guides

Top 5 Reasons Your Thermostat...

Regular maintenance and checks of both the thermostat and the heating and cooling system c...

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What is a Low Loss Header?

30th May, 2025 Guides

What is a Low Loss Header?

A low loss header is an essential part of a heating system. It acts as a bridge between th...

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Does a Gas Boiler Use Electricity?

30th May, 2025 Guides

Does a Gas Boiler Use Electric...

Gas boilers primarily run on natural gas or liquefied petroleum gas (LPG) to heat homes. N...

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

30th May, 2025 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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Different Types of Radiators

30th May, 2025 Guides

Different Types of Radiators

Radiators come in various types and materials, offering different benefits. Choosing the r...

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S Plan Heating System

30th May, 2025 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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Header Tank Overflowing

30th May, 2025 Guides

Header Tank Overflowing

A header tank, also known as a feed and expansion tank, serves an important role in an ope...

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Egg Timer on Vaillant Boiler

30th May, 2025 Guides

Egg Timer on Vaillant Boiler

The egg timer symbol on a Vaillant boiler signifies the activation of the anti-cycling fun...

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Plumber and Heating Engineer - What's the Difference?

30th May, 2025 Guides

Plumber and Heating Engineer -...

When deciding whether to call a plumber or a heating engineer, it’s important to know what...

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Ideal Room Temperature

30th May, 2025 Guides

Ideal Room Temperature

Comfort in living spaces is crucial for wellbeing. The ideal room temperature can vary bas...

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