Avoiding Snags and Delays: Quality Control for Commercial Air Conditioning Installations

Air conditioning is one of the most common sources of snag lists in commercial building projects.

Poor pipe routing, noise issues, inadequate access, or incomplete commissioning can all delay practical completion.

If you’re responsible for M&E delivery, you need a clear quality control process. One that catches problems early and holds your air conditioning subcontractors accountable.

This blog outlines how to manage quality from design to handover—using lessons from real projects across Hampshire, Berkshire, and Surrey.

We’ll also share the exact checks, documents, and milestones you should use to reduce risk and improve outcomes.

Why air conditioning leads to project delays

Unlike some services, air conditioning touches every part of the building.

It affects:

• Electrical load
• Fire strategy
• Acoustics
• Maintenance access
• BMS integration

Problems usually arise when:

• Systems are underspecified
• Installers don’t follow the design
• Key reviews are skipped
• Sign-off happens too late

In busy towns like Oxford and Wokingham, where floorplans are tight and timelines are fixed, this results in rework, disputes, and missed deadlines.

Quality risks you can’t ignore

From site inspections across Surrey, common air conditioning problems include:

• Condensate drainage routed uphill or without air breaks
• Ductwork too close to sprinkler heads
• Isolated units with no service access
• Controls not mapped to zone plans
• Incomplete commissioning records
• Non-compliance with acoustic limits under BS 4142

These issues are avoidable—but only if you build in quality checks early.

What quality control should include

Pre-installation

• Final review of issued-for-construction drawings
• Physical coordination check of risers and ceiling voids
• Pre-start meeting with the installer
• Plant space and access review

During installation

• Spot checks on pipe insulation, fixings, and routing
• Inspection of drain falls and supports
• Review of control cable routing and containment
• Acoustic isolation mounting (where required)

Pre-commissioning

• Leak test reports for refrigerant pipework
• Electrical testing on each unit
• Function test of BMS interface or standalone controller
• Installation photos logged with date and location

Commissioning and handover

• Commissioning sheet signed by F-Gas certified engineer
• Verification of airflow and refrigerant pressures
• O&M manual including warranties, drawings, and test results
• End-user demonstration and sign-off

These steps ensure compliance with TM44 inspections, F-Gas rules, and warranty terms.

Case study: Mixed-use site in Newbury

On a five-storey building in Newbury, the M&E lead created a checklist system for all subcontractors. For air conditioning, this included:

• Weekly photo reports
• Pre-completion sign-off of all rooftop condenser mounts
• Final airflow testing witnessed by the client rep

As a result, the final TM44 inspection passed first time. No additional commissioning visits were needed. The site handed over without any cooling-related snags.

Local challenges in Hampshire, Berkshire, and Surrey

Basingstoke

Retail units often install cooling late, which limits access to ducts and controls. A quality control plan avoids conflicts with ceilings and lighting.

Reading

High-rise builds in the town centre must coordinate rooftop units with planning and noise requirements. Proper checks ensure compliance with BS 4142 and local acoustic targets.

Guildford

Older buildings often involve retrofitting cooling into tight spaces. Without visual inspection of duct routes, rework is almost guaranteed.

Farnham

Sites with strict planning requirements need confirmation that condenser placement and noise ratings meet local authority conditions before commissioning.

Tools and documentation that support quality

Use these tools to reduce risk:

• Installation checklists signed by site managers
• Digital photo logs with date and floor reference
• Weekly quality walk sheets
• QR-coded commissioning tags linked to individual units
• Acoustic reports from third-party specialists

Also refer to government guidance on managing refrigerant and cooling system safety (UK HSE).

What to expect from your subcontractor

Subcontractors must provide:

• Proof of F-Gas registration
• Commissioning sheets signed and dated
• Drawings marked “as-installed”
• Noise level confirmations (if required)
• O&M manual with clear contacts for support or maintenance

Request these early and track them throughout the project—not just at handover.

Final checks before handover

Before you sign off:

• Confirm every unit has been powered, tested, and logged
• Verify that access panels are unobstructed
• Check that condensate drains are labelled
• Confirm that all control zones match your plan
• Ensure end-users have been trained or briefed

This protects the programme and avoids post-handover callouts.

About the author

Dr. Julian Carter
Chartered Building Services Engineer, Technical Advisor at ClimateWorks

Dr. Julian Carter brings over 20 years of experience in building services engineering, specialising in air conditioning, ventilation, and compliance. He has worked with M&E consultants, developers, and main contractors across Hampshire, Berkshire, and Surrey—delivering commercial systems for offices, schools, medical clinics, retail units, and industrial sites. Julian advises on technical integration, early-stage planning, and quality assurance for commercial air movement systems. He is a chartered engineer and contributes to UK-wide standards on HVAC commissioning and lifecycle performance.

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