Building Air Conditioning · Homes & Businesses
Cassette & Ducted Air Conditioning Servicing
Cassette and ducted servicing covers filters, heat-exchanger condition, fans, condensate pans, pumps and accessible distribution paths in building AC systems.
Scope and equipment
Ceiling cassettes often lift condensate using a pump and float switch. Check the pan, pump outlet and drain route with a controlled water test, protecting finishes below. Restricted discharge or a failed float can stop a unit or cause ceiling staining without any refrigerant fault.
Ducted systems require an airflow assessment as well as filter cleaning. Inspect accessible return paths, grilles and flexible duct connections; static-pressure settings and filter specifications must suit the indoor model. Whole-building duct cleaning is not automatically included in an indoor-unit service.
Symptoms and inspection priorities
Reduced airflow, musty smells, dirty filters, weak temperature control and drain staining warrant an inspection. Before opening equipment, note modes, set points, alarms and which zones are affected. Safe user checks are limited to accessible filters and controller instructions.
Compare power and control operation with airflow and temperatures. An engineer checks connections and components using safe isolation and model-specific procedures. Signs of refrigerant loss require leak investigation, not an automatic top-up.
Cleaning, repair and compatible parts
Agree which components are cleaned, which need further fault-finding and whether replacement is economical. Filters, pumps, motors and controllers must match the installed model and electrical specifications; a brand name alone is not a compatibility check.
Support includes assessed equipment from Daikin, Mitsubishi Electric, Toshiba, Fujitsu, Panasonic, Samsung and LG. Manufacturer names describe equipment, not an approval or authorisation. Building refrigerant work needs appropriate qualifications.
Post-work checks and service records
Reassemble panels and filters, restore the agreed settings and confirm operation under a representative load. Check drainage and any pump safety interlock, compare indoor/outdoor behaviour and record abnormal readings or outstanding defects. Cooling and heating tests are selected for the system design and conditions.
Cost factors and booking
All work is quoted on request. The scope depends on the equipment, fault, access, labour, parts and any refrigerant work. Diagnostic findings and the proposed repair should be agreed before additional work proceeds; a service visit is not a promise that every repair or replacement part is included.
Our central operation covers London and the South East/M25. For other UK regions, send the site postcode so coverage, equipment suitability and appointment availability can be confirmed before a visit is agreed.
Use the ServiceM8 booking form for an engineer or quotation with the site postcode, indoor and outdoor model references, fault description, controller code and access requirements. Select the requested urgency; emergency or within-48-hour selections are requests, not guaranteed attendance times. Refrigerant and electrical work require appropriately qualified personnel.
Cassette pumps and ducted airflow: different service priorities
A cassette distributes air directly through its ceiling panel, whereas a concealed ducted unit relies on a return path and supply network. A clean cassette filter cannot correct a blocked discharge grille or failed fan. On ducted equipment, inspect accessible plenum connections, filter grade, dampers and return restrictions. Compare the installed external static pressure setting with the unit’s permitted range; fan noise and weak terminal airflow can indicate that the distribution system and unit are mismatched.
Cassette pans commonly use a lift pump and level switch. Sludge, outlet obstruction, an incorrect lift height or a failed pump can produce overflow or protective shutdown. Ducted trays may use gravity drainage and require the trap arrangement specified for the unit’s pressure conditions. Missing or unsuitable traps can impede drainage. Surface condensation on cold ducts and poorly sealed insulation can create ceiling stains independently of a pan overflow.
Diagnosis, electronics and parts matching
Observe when the symptom occurs: startup, humid weather, high fan speed or only after prolonged cooling. Carry out a controlled drain test with protection below the unit. Compare supply and return temperatures alongside airflow; low airflow can freeze the evaporator, while refrigerant shortage or abnormal EEV operation can also cause icing. Melting ice is a secondary water source, so clearing a drain without investigating ice may leave the main defect unresolved.
Inverter drives, fan feedback and indoor/outdoor communication faults need the service information for the actual model. Daikin SkyAir, Mitsubishi Electric Mr Slim, Toshiba RAV, Fujitsu and Panasonic PACi cassettes or ducted ranges have different pump assemblies, panels, motors and controller requirements. Match fan rotation, motor electronics, pump lift duty, level-switch contacts and PCB revision. A replacement ceiling panel may also need the correct sensor and louver connections.
Post-work evidence and access-dependent costs
Refit insulation, access panels and filter seals, then prove the drain under controlled water flow and actual cooling condensate. Verify the high-level shutdown where fitted and check for leakage at joints. On ducted systems, record fan settings and check representative outlets without presenting a basic service as a complete building air-balance exercise. Record the temperature split, conditions and unresolved distribution defects. Refrigerant pressures and F-Gas records are addressed where justified by the work rather than as an automatic invasive test.
Prices are quoted on request. Ceiling height, access hatches, nearby finishes, pump location, deep coil cleaning and duct accessibility can affect labour more than the nominal cooling capacity. Whole-building duct cleaning, scaffolding or substantial duct alterations require a separate scope. Use the ServiceM8 booking with unit references and access photographs; disclose any known asbestos restrictions, permit requirements or occupied areas before attendance is agreed.
Frequently asked questions
Does ducted servicing include all ductwork?
Only the agreed accessible scope. Whole-building duct cleaning, air balancing and hidden distribution alterations are separate activities.
Why does a cassette stop when its pump fails?
A level switch or safety interlock may stop cooling before overflow. The pump, drainage route and protective contact need testing together.
Can a stronger fan solve poor duct airflow?
Not necessarily. Restriction, leakage and duct design must be assessed against the indoor unit’s available static pressure.
Are all cassette pumps interchangeable?
No. Lift duty, connections, dimensions, level sensing and electrical ratings must match the installed assembly.
What testing follows cleaning?
Drain flow, pump safety operation, fan speeds, louvers where fitted and representative cooling performance are checked after reassembly.
How should I book?
Send cassette or ducted model plates, site postcode, ceiling height and hatch details through ServiceM8 for a quoted and confirmed visit.