AHU & FCU SYSTEMS

Conditioned air, delivered properly.

Servicing and repair for chilled-water and direct-expansion air-handling and fan-coil equipment.

AHU & FCU systems — illustrative photograph — Illustrative equipment / stock photography

01 / UNDERSTAND THE SYSTEM

AHU & FCU systems in context.

An air-handling unit moves and conditions air through a building’s ductwork. Cooling coils may use chilled water or refrigerant. Fan-coil units provide local air circulation and cooling.

Airflow, coil condition and condensate drainage work together to deliver comfortable air to the space.

Air-handling units

Typically serve ducted areas through sections for air movement, filtration and conditioning.

Fan-coil units

Provide local cooling and air circulation. Access to filters, the coil and drainage remains important.

Chilled-water & DX coils

The coil may receive chilled water or refrigerant; troubleshooting and connections differ.

VISUAL EXPLAINER

See how the parts connect.

**System overview.** Read the labelled connections alongside the equipment description below. Simplified illustration; actual arrangements vary.

Read the detailed visual guide +

02 / SCOPE & CONDITION

What we look at.

Area	What matters	Why it matters
Weak airflow	Filter condition, fan performance and duct restrictions	Cooling problems may begin on the air side.
Water leakage	Drain pan, trap, pipe route and pump where fitted	A drain arrangement must suit the unit and operating pressure.
Temperature control	Sensors, valves, actuators or refrigerant controls	The installed cooling type determines which controls apply.

Work that can be included

Filters, coils and drain pans
Fan motors, bearings and belt arrangements
Control valves, thermostats and actuators
Condensate drainage and insulation

Define the scope before work starts.

Parts, quantities, access, shutdowns and reinstatement are confirmed against your site and equipment. Additional defects or specialist works are discussed separately.

Prepare a clearer enquiry

03 / HOW THE WORK PROGRESSES

A clear route from enquiry to completion.

01
Review access
Identify ceiling openings and safe access to service sections.
02
Inspect air & drainage paths
Assess the filters, coils, fans and condensate system.
03
Complete agreed work
Service, repair or replace the identified components.
04
Verify operation
Check air movement, control response and drainage.

04 / COMMON QUESTIONS

A little more clarity.

What is the difference between a chilled-water and DX AHU?

The cooling medium differs: chilled water flows through one type of coil, while refrigerant flows through a DX coil. Maintenance and fault diagnosis must match the installed system.

Does an AHU always use chilled water?

No. An AHU can use a chilled-water coil, a DX refrigerant coil or other conditioning sections depending on its design.

Why is a secondary drain pan sometimes proposed?

It can provide additional protection below equipment, where appropriate. It does not replace repair of the primary drainage fault.

KEEP EXPLORING