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Commercial ventilation

Air handling unit installation, replacement and service

AHU replacement, EC fan upgrades, controls and planned servicing.

  • From £9,950 + VAT per unit
  • Free survey on the UK mainland
  • Airflow tested and recorded
Get a guide price0800 088 6341
Air handling unit on a commercial rooftop

An air handling unit (AHU) is the central plant that filters, moves and often heats, cools or recovers heat from the air for a building's ventilation system. We replace ageing units, upgrade fans and controls, and service AHUs so they keep delivering their design airflows.

How it works

Many AHUs in older offices, schools and retail units run on belt-driven fans, clogged filters and controls nobody understands. Replacing the fan section with EC fans, or the whole unit with a modern heat recovery AHU, can cut running costs and noise while restoring airflow. New units must meet current ecodesign rules for fan efficiency and heat recovery.

Replacements often involve crane lifts, roof work and out-of-hours changeovers. We plan the lift, temporary arrangements and isolations with you so the building can keep working.

Options we fit

Like-for-like replacement

New unit in the same position, connected to existing ductwork.

EC fan retrofit

Belt-driven fans replaced with direct-drive EC fans.

Controls upgrade

New controls, sensors and BMS integration.

Planned servicing

Filters, belts, coils, drains and controls on a schedule.

Signs you need this

  • Rising energy bills from old plant
  • Frequent belt or fan failures
  • Noisy plant rooms or rooftop units
  • Filters that are never changed
  • Corroded casings or leaking drain trays
  • Rooms that no longer get enough air

Guide prices

Air handling units (AHU) guide prices
WorkGuide price
Air handling unit replacement, small to medium unit, like-for-like position (per unit)£9,950–£34,950 + VAT
Air handling unit service: filters, belts or EC fan check, coils, controls (per unit per visit)£195–£395 + VAT

Guide prices using West Midlands (our baseline) rates. Home prices include VAT at 20%; business prices exclude VAT. A guide price is not a quote: we confirm a fixed price in writing first. London is about 20% higher and the North East about 8% lower.

What happens, step by step

  1. Survey

    Unit condition, duty, access and lifting arrangements.

  2. Options

    Repair, retrofit or replace, with costs and running savings.

  3. Plan

    Crane, permits, isolations and out-of-hours timing.

  4. Install

    Unit or components fitted and connected.

  5. Commission

    Airflows and controls set, records handed over.

The rules that apply

England

In England, ventilation is covered by Part F of the Building Regulations and its guidance, Approved Document F (2021 edition). Workplaces must also be ventilated with a sufficient quantity of fresh or purified air under the Workplace (Health, Safety and Welfare) Regulations 1992.

Wales

Wales has its own Part F ventilation guidance, published by the Welsh Government, and work is checked by building control. The Workplace (Health, Safety and Welfare) Regulations 1992 also apply, requiring sufficient fresh or purified air.

Scotland

In Scotland, ventilation is covered by the Building (Scotland) Regulations and section 3 of the Technical Handbooks, and most building work needs a building warrant first. The Workplace (Health, Safety and Welfare) Regulations 1992 apply in Scotland too, requiring sufficient fresh or purified air.

Northern Ireland

In Northern Ireland, ventilation is covered by the Building Regulations (Northern Ireland) and Technical Booklet K. Northern Ireland has its own Workplace (Health, Safety and Welfare) Regulations (Northern Ireland) 1993 with the same duty to ventilate.

Questions people ask

How much does an AHU replacement cost?

A small to medium AHU replacement in the same position typically costs £9,950 to £34,950 excluding VAT, depending on size, heat recovery and lifting.

How often should an AHU be serviced?

Most AHUs need servicing at least twice a year, with filters changed more often in dirty environments. SFG20 schedules are commonly used to set frequencies.

Is it worth replacing belt-driven fans with EC fans?

Often yes. EC fans are usually more efficient, quieter and need no belt changes, and the retrofit can cost much less than a new unit.

Can you work out of hours?

Yes. Changeovers and crane lifts are often done at weekends or evenings to avoid disruption.

What does an AHU service cost?

A service visit typically costs £195 to £395 per unit excluding VAT, depending on size and access.

Do you work on rooftop units?

Yes, with safe access arranged for roof work.

Related services

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