Ducted Air Conditioning

What is ducted air conditioning?

Ducted air conditioning is a system whose indoor unit is hidden in the ceiling space. It sends conditioned air through ducts to grilles in each room, so only the grilles show. Climate Flow Limited installs, services and repairs ducted air conditioning for homes, offices, shops and hospitality sites across London and surrounding areas.

Mitsubishi Electric's own description of its ceiling concealed ducted indoor units says the units sit within the ceiling space, and the duct layout can be arranged so the airflow suits the room. A ducted system has three main parts:

• The indoor unit. This is the fan coil in the ceiling void: a fan that blows room air across a coil of cold refrigerant pipe. It draws air from the room and conditions it.
• The ductwork and grilles. These carry air from the unit into each room and back to it.
• The outdoor unit. The condensing unit outside rejects the heat that the indoor unit took out of the rooms. Refrigerant pipework links it to the indoor unit.

Where does ducted air conditioning suit?

Ducted air conditioning suits spaces where nothing but a grille should show and where there is a ceiling void for the unit and its ducts. These are the usual fits:

• Hotels, bedrooms and meeting rooms. Manufacturers make ultra-thin ducted units for places where low noise is wanted, and they name hotels as an example.
• Buildings with a shallow ceiling void. Mitsubishi Electric lists slimline ducted units made for buildings where ceiling void space is limited. A survey confirms what a given void will take.
• Shops and larger open spaces. Ducted units with higher external static pressure (how hard the fan can push air along the ducts) are aimed at retail and warehouse spaces. They give the designer more room to arrange the ductwork.
• Offices and homes. The ductwork can carry air to grilles in different parts of a floor, which keeps walls and ceilings clear of indoor units.
• Refurbishments and fit-outs. Ceilings are already open during this work, so the ducts can be routed before the space is finished.

Ducted, cassette or VRF: which suits the space?

A cassette unit is an indoor unit set into the ceiling. Its face shows in the room and it needs no ductwork. For an example, see the cassette air conditioning installation for a restaurant on Orsman Road. VRF (variable refrigerant flow) is a system where one outdoor unit serves many indoor units, and ducted units are among the indoor units made for it. For an example, see our VRF maintenance work at Energie Fitness Gym. The survey decides between these systems. It looks at the ceiling, the rooms served and how the space is used.

What does a ducted installation involve?

A ducted installation runs from the survey to the handover, and most of the work takes place in the ceiling void. In a finished building, ceilings may need opening and making good afterwards. Someone who can give access to the ceiling, the outdoor unit position and the electrical supply needs to be on site.

1. Survey. The engineer measures the ceiling void and plans the duct routes and grille positions. They also choose where the outdoor unit goes and plan the pipe route, the condensate drain (the pipe that carries away water the unit collects) and the power supply.
2. Design. The engineer picks the indoor unit to suit the void and the duct runs, and agrees the grille layout with you.
3. Indoor unit and ductwork. The unit is fixed in the void, then the ducts and grilles are fitted and the condensate drain is connected.
4. Outdoor unit and pipework. The condensing unit is mounted and the refrigerant pipework is run between the two units.
5. Commissioning and handover. The pipework is pressure-tested and evacuated (air and moisture pumped out) before the system is charged with refrigerant. Then the system is run and checked, and you are shown the controls and given the records.

The law requires a company that installs, repairs or maintains air conditioning for someone else to be certified by an approved body to work with F gas. Climate Flow is F-Gas certified.

Signs a ducted system needs attention

Because a ducted system is out of sight, the first signs usually show at the grilles or on the controller:

• weak airflow at one or more grilles;
• one room staying warmer than the others;
• a water stain or a drip on the ceiling near the unit or a grille;
• a new rattle, hum or whistle from the ceiling;
• an error code on the controller;
• the outdoor unit running but the rooms not cooling.

Never open the refrigerant circuit or add refrigerant yourself. That work is for a certified engineer.

How is ducted air conditioning maintained?

Ducted air conditioning needs regular servicing, and the operator has legal duties as well. GOV.UK guidance makes whoever uses air conditioning that contains F gas responsible for getting it checked for leaks. For the lowest charge band that needs checks, the check is due at least once every 12 months. The charge band is set by how much refrigerant the system holds. Larger charges are checked more often, and smaller systems may fall below the threshold. The guidance is plain: you are breaking the law if you do not have the right leak checks in place, or do not fix leaks.

Operators must also keep F gas records for 5 years. These include the gas in the system, any gas added during maintenance and the leak-check results. On a service visit we check:

• filters in the indoor unit or the return grille
• supply and return grilles, and airflow at each one
• the condensate drain and its pump, where one is fitted
• refrigerant pipework and joints for signs of a leak
• the outdoor unit's coil, fan and mounting
• controls, settings and any stored error codes

We install and service Daikin, Mitsubishi Electric, Mitsubishi Heavy Industries, Fujitsu, Toshiba, Panasonic and Samsung air conditioning. For breakdowns we offer 24/7 emergency callouts.

Ducted air conditioning from Climate Flow

Climate Flow designs, installs and maintains ducted air conditioning for homes and businesses in London and surrounding areas. We also work on cassette, split, multi-split and VRF systems, which are listed with our other work on the all services page. Climate Flow Limited, 2 Engineers Way, Wembley, London HA9 0JS. Call 020 3488 5452 or request a quote.

This guide is general information, not a survey or a quote for your site; every system is different, so an engineer needs to see yours before any work is priced.