The 10 best commercial boiler installers in the UK (2025)

Commercial boiler systems are the backbone of heating in factories, warehouses, schools, hospitals, offices, and public buildings across the UK. A reliable, efficient boiler installation directly impacts energy performance, operational uptime, and long-term running costs. Choosing the right contractor ensures your system is installed safely and optimised for efficiency.

What to look for in a commercial boiler installer

The best commercial boiler installers

Here are ten of the UK’s leading commercial boiler installation contractors – recognised for their technical capability, reliability, and proven delivery across multiple sectors.

1. Unitary Engineering Services (UES)

Best for: Turnkey commercial boiler installations and plantroom upgrades

Locations: Bristol, Southwest England, and South Wales focused, with nationwide capabilities

Unitary Engineering Services (UES) delivers end-to-end commercial boiler installations and replacements across schools, depots, churches, and complex commercial estates. Their in-house engineering team manages the whole process – from heating system design and plantroom layouts to installation, testing, and commissioning.

UES combines boiler work with wider mechanical and electrical services, including gas distribution, controls, and renewables. This whole-building approach helps clients modernise ageing plant rooms, improve efficiency, and align projects with long-term energy and carbon-reduction goals.

Key benefits of UES:

• Commercial boiler services trusted by organisations including Skanska, First Bus, Veolia, Wiper & True, Sisk, Matter, and multiple education clients
• Fully accredited (Gas Safe, NICEIC, CHAS Elite, SafeContractor) with B Corp Certification for verified sustainability and governance standards
• In-house design, project management, and installation teams delivering safe, compliant boiler plant and associated controls
• Capability to integrate boilers with warm air systems, building management systems (BMS), solar PV, and broader HVAC upgrades for whole-site performance

Key case studies and results:

• £1.2 million heating and controls upgrade for a water-damaged school in Oxfordshire
• Rapid replacement of a failed boiler with a high-efficiency system, reducing long-term costs by 20%
  
• Industrial boiler and hot water upgrade to modern, energy-efficient solutions for a major transport depot
  
  

2. MHL (Moorhouse Heating Ltd)

Best for: Nationwide commercial boiler replacements and modernisation

MHL specialises in large commercial gas, oil, and LPG boiler installations across the UK. With over 30 years of experience, they support schools, healthcare, hotels, FM providers, and commercial estates with replacement plant, upgrades, and compliance.

3. JCW Energy Services

Best for: Multi-site commercial boiler installations for national organisations

JCW delivers commercial gas boiler replacements, plantroom upgrades, controls integration, and servicing across the UK. Their dedicated commercial heating division supports local authorities, national retailers, and education estates.

4. NG Bailey

Best for: Large-scale commercial boiler and plantroom projects

NG Bailey is one of the UK’s largest independent mechanical and electrical (M&E) contractors, with strong capability in mechanical systems, boiler plant, and heating upgrades. They deliver complex, multi-technology projects across commercial offices, manufacturing sites, hospitals, and large estates.

5. Balfour Beatty Kilpatrick

Best for: Industrial boiler installations within major infrastructure projects

Balfour Beatty Kilpatrick manages the mechanical packages on large infrastructure and commercial developments. Their boiler installations typically form part of major plantroom upgrades, shutdowns, and compliance-led replacement works in high-demand environments.

6. SPIE UK

Best for: Boiler plant with integrated BMS and complex system controls

SPIE UK delivers commercial boiler installations nationwide, specialising in integration with building management systems and wider energy plant. Their clients include blue-chip commercial estates, government buildings, and industrial facilities.

7. Kensa Contracting

Best for: Low-carbon and hybrid heating plant (gas + heat pump combinations)

Kensa Contracting is a national specialist in heat pump and hybrid system deployments, often pairing high-efficiency boilers with low-carbon technology. They support decarbonisation programmes for councils, housing associations, and commercial estates.

8. Mitie Technical Services

Best for: National facilities-led commercial boiler installation and lifecycle management

Mitie delivers commercial boiler replacements and heating plant upgrades across the UK through its technical services division. Their heating engineers support hospitals, universities, airports, retail estates, and government buildings with large-scale boiler projects.

9. SSE Contracting (now EQUANS / Equans UK & Ireland)

Best for: Major public sector boiler upgrades and district heating plant

Equans delivers commercial boiler installations as part of large M&E and energy performance projects. Their heating work spans hospitals, education campuses, civic buildings, and energy centre refurbishments.

10. Integral (JLL)

Best for: Boiler plant installation and national commercial estate support

Integral provides commercial boiler installation and mechanical upgrades for national FM portfolios. Their engineers deliver plant replacements, plantroom refurbishments, and compliance upgrades across offices, logistics centres, and corporate real estate.

The top 10 commercial boiler installers at a glance

Below is a quick reference summary of the UK’s leading commercial boiler installers.

Why Unitary Engineering Services leads the way

Choosing the right commercial boiler installer is ultimately about securing long-term performance, safety, and operational resilience. The best projects combine strong technical design, careful installation, and reliable lifecycle support.

Across the industry, contractors that understand how boilers interact with wider building systems, from controls and electrical infrastructure to decarbonisation plans – consistently deliver better outcomes. This integrated approach helps businesses reduce energy use, avoid unplanned downtime, and prepare their estates for future regulatory change.

UES exemplifies this standard. Their engineering depth, cross-discipline capability, and proven delivery across education, transport, heritage, and commercial sites place them among the UK’s most dependable contractors for boiler plant upgrades.

Discover how a new commercial boiler installation can transform your facility. Explore our case studies or learn more about our commercial heating services.