Central Heating & Boilers

Hertfordshire’s largest independent central heating installer

Since 1993 Gas Mark 1 have been the largest independent installers of new boilers and central heating systems in Hertsmere, Three Rivers, Dacorum, Broxbourne, North and East Herts. We’ve built up our reputation by providing first class service and quality installations as well as superb value for money.

We recommend only the leading manufacturers of appliances and fittings to ensure the longevity and reliability of our installations. Gas Mark 1 install approximately 400 boilers a year.

Boiler Installations

We provide hassle-free quality boiler installations by our experienced Gas Safe registered engineers.

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Outdoor Vaillant aroTHERM heat pump installed in a landscaped garden, offering quiet and efficient renewable heating for Hertfordshire homes.

Air Source Heat Pumps

Looking for a greener, more efficient way to heat your home?

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Radiators

We can supply and install all of the top brands of designer or standard radiators and valves.

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Underfloor Heating

Our expert staff can provide you with a tailored design and installation of underfloor heating in your home.

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Thermostats & Smart Controls

From on/off timers to self-learning internet controlled thermostats we have the products to suit your exact needs.

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In-house trained Gas Safe Engineers

We can install any boiler brand available but through our vast experience we recommend either Vaillant or Worcester Bosch boilers, which can come with a parts and labour warranty of up to 10 years.

All Gas Mark 1’s engineers are trained in-house and registered with the latest qualifications. Every completed boiler installation is issued with a Gas Safe certificate and commissioned to comply with the latest Part ‘L’ Building Regulations.

Meet Our Team

Free Home Surveys

We offer free home surveys for central heating upgrades and boiler replacements, which are carried out by ex-engineers who have over 30 years of experience in the industry. This ensures that our customers are given clear, knowledgeable and impartial advice that best suits their needs.

Gas Mark 1 pride ourselves on the quality of our workmanship and well over 50% of all new work is generated by the recommendations of past customers.

Contact Gas Mark 1 on 01923 231780 to arrange a free survey to your home.

Arrange a FREE survey

Wayne Harris

4 months ago

We’ve recently had three bathrooms fully refurbished along with a complete new heating system and boiler relocation, and our experience from start to finish has been fully deserving of five stars.

The whole team have been very professional throughout. From our first visit to the showroom and throughout consultations, site surveys and delivery of the project, the communication has been clear and consistent, and nothing ever felt like too much trouble — the team have a genuine “can do” attitude and creative approach that is focused on delivering great service and a fantastic end result.

The project has felt like a partnership rather than a blunt client/contractor relationship and they have worked with us from the start to explain options, offer suggestions and work with us to get the details right.
Just as importantly, they were reliable and respectful of our home — turning up when they said they would, keeping things tidy, and keeping the schedule on track.

Stew was extremely helpful during the consultation and design process and Jason was incredibly meticulous with the central heating works.
Special mention goes to Tom H. for his attention to detail and for working tirelessly to ensure that we were satisfied.

We’ll definitely be using Gas Mark 1 / Herts Bathrooms again for future work and wouldn’t hesitate to recommend them.

Martin Geoffrey Moore

A nice experience. We recently refurbished our bathroom and these guys were great. We were very impressed by their total attention to detail, their focus on the job and the way they made every effort not to leave any debris or waste behind them. Thank you!

Jo Windmill

Tom and Harry, really professional - great job! Would recommend. Thank you 🙏

Kevin Petty

6 months ago

Thanks to Charlie, Tom and all the team for a fantastic job. We are delighted with our new bathroom. From start to finish great care and organisation has been taken to keep disruption to a minimum.
We have no hesitation in recommending Gas Mark 1

James

7 months ago

Very happy customers! Gas Mark 1 and Herts Bathrooms were excellent every step of the way. Communication was fantastic throughout and the work was undertaken to our complete satisfaction. Gareth (engineer) and his team were polite, considerate and very easy to get on with. Highly recommended

Libby Pfeiffer

We are delighted with our new kitchen. It is lovely and most importantly, it was put in so well by GasMark1.
Alex and co were totally professional, polite (and nice).
Special mention and thanks for Alex, a Perfectionist!

Natasha Proctor

Would absolutely recommend Gas Mark 1 - we got our boiler replaced, a new radiator installed and an electric shower put in the bathroom and the team were brilliant. Always arrived on time each day, were very knowledgeable and great at explaining what was happening and left the house without any mess. We'll be getting them back in for work on the kitchen next!

Coral

8 months ago

We had Gas Mark 1 round to install our washing machine. Barney visited this morning to survey the job and managed to get two guys to install a couple of hours later. Great service as usual. They installed our kitchen 7 years ago and were reliable then. Great to see their customer service is still the same as are the three guys that came today, so not a high staff turnover.
Wouldn't hesitate in recommending this company.

Central Heating & Boilers

Hertfordshire’s largest independent central heating installer

Boiler Installations

Air Source Heat Pumps

Radiators

Underfloor Heating

Thermostats & Smart Controls

In-house trained Gas Safe Engineers

Free Home Surveys

Google Reviews

Contact us