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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

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 - A Guide to the Range

20th May, 2026 Reviews

Viessmann Vitodens - A Guide t...

Viessmann is one of the best and most reliable boiler brands on the market with their adva...

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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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Viessmann Heat Pump - 2026 UK Guide

20th May, 2026 Reviews

Viessmann Heat Pump - 2026 UK...

Viessmann offers an impressive range of heat pumps in the UK for 2026, catering to various...

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Viessmann Combi Boiler Costs

20th May, 2026 Guides

Viessmann Combi Boiler Costs

Viessmann combi boilers are renowned for their efficiency and technological advancement.

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Vaillant PCB

20th May, 2026 Guides

Vaillant PCB

A Vaillant boiler Printed Circuit Board (PCB) is a vital part of a modern boiler system. I...

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Vaillant Boiler Flue Extension

20th May, 2026 Guides

Vaillant Boiler Flue Extension

This guide dives deep into what flue extensions are, why they are important, and how to in...

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Vaillant Ecotec Pro Review

20th May, 2026 Reviews

Vaillant Ecotec Pro Review

Vaillant's Ecotec Pro combi boiler series is renowned for providing efficient heating and...

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Vaillant EcoTEC Plus

20th May, 2026 Reviews

Vaillant EcoTEC Plus

Vaillant UK manufactures some of the finest boilers on the market, highly efficient and ec...

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