Fan Coil Units (FCUs)
Fan coil units (FCUs) located in the ceiling voids are the means by which heating and cooling is provided in your apartment. This section looks at FCU maintenance and common FCU problems: please refer to the sections on heating and cooling to see how to use the heating and cooling in your apartment.
FCU electricity consumption
The FCUs contain heating elements of between 2kW and 3kW. Some rooms (lounges) may be served by two FCU units and combined kW elements totalling 5kW. You can find the heating element size of your FCUs in the excel spreadsheet here. Running an FCU with a 3kW heating element will use 3 units (kWh) of electricity per hour.
FCU maintenance
It is the resident’s responsibility to maintain their apartment's FCUs, and ensure that the filters are cleaned on a regular basis. You can find the procedure for cleaning/replacing fan coil filters here. They can be vacuumed in situ, or removed for a more thorough clean. It is recommended that the filters be cleaned twice a year: do not use your cooling unless the filters have been cleaned within the past six months.
view of an fcu through an open ceiling panel
Filters waiting to be cleaned
You can find troubleshooting notes collated by the supplier of our FCUs here. Technical information on the operation/maintenance of the FCUs can be found here and wiring diagrams here. These may be helpful to your maintenance technician.
Locating your FCUs and access
You can find out details on the location and size of the FCUs in your apartment by checking this spreadsheet, which was prepared by the company that supplied the FCUs when they were installed in 1999. This includes serial and model numbers: you may need to unhide the columns with this data. Unfortunately the spreadsheet does not include the penthouse apartments.
The living room FCU(s) are usually located in the kitchen/breakfast area ceiling: they are accessed through the fire-resistant ceiling tiles (usually in blocks of six or eight: If you have two FCUs serving your living area there will be two lots of ceiling tiles). Please see our guidance note on how to remove the ceiling tiles. If they have been painted over and/or sealed with silicone, the tile edge may first need to be cut with a stanley knife/sharp blade in order to be able to remove the tile from its seating. The tiles are very fragile - be careful as you remove them.
The bedroom FCU(s) are accessible through drop-down ceiling access panels in the master bedroom and/or hallway. NB: You will need a 'key' or flat-headed screwdriver to unlock the access panels. Be careful as you lower them - they are very heavy as they have a fire-resistant lining.
Common problems
Ambient air is coming out of the vent instead of heated air. The most common reasons for this are a dirty filter (i.e., insufficient air circulation to allow the heating element to come on) or a failed differential pressure switch. A replacement dps costs <£40. Replacement requires the engineer to access the FCU by removing completely the bottom panel of the unit. This can be very difficult for FCUs located in the kitchens, as not all of the retaining screws are easily accessible, and the framework that supports the ceiling tiles further hinders access.
Ambient air is coming out of the vent instead of cooled air. The damper that controls whether the air is being directed over the heating or the cooling coils has got stuck, and air is not being blown over the cooling coil, or: the Bellimo actuator that moves the damper into position has failed.
No air is coming out of the FCU. Check that the Hager unit (located in the same cabinet as the electricity meter) is not switched off.
The FCU appears to have a water leak. This could be caused by a dirty filter, blocked condensate tray, or a faulty valve.
A dirty filter wil impede the flow of air over the chiller coil, causing frost to form (which then melts).
When the cooling is running a significant volume of condensation is produced. If the drain from the tray is blocked, water cannot drain away.
Valves connecting the cooling coil to the child water supply may have eroded and require replacing.
Very little air is being expelled through the FCU air vents.
Check that you have not blocked the inlet vents that provide the air supply to the FCUs
Check that the FCU filters are not blocked with dirt and dust. NB the filter is located on the FCU unit.
Canary Riverside's bespoke system
Canary Riverside was built with a very unusual heating system. The cooling is provided by way of centrally generated chilled water, which is pumped through the residential buildings. Ordinarily heating is provided the same way: centrally generated heated water being pumped through the buildings, passing through the FCUs. This is not the system here.
At Canary Riverside the heating is provided by electrical heating element(s) located within each FCU. The FCU effectively acts as a large fan heater, blowing air over heating elements (2-3kW) and out through the vents located just below ceiling level. It is not particularly efficient, and is expensive to run. An apartment with two FCUs serving a large living room will use 5kW per hour. If you would like to find out the number of FCUs in your flat and the associated kW heating output please email us: we have access to the system designer's original schedule of FCU units.
Our FCUs are what are known as 'airside control' units. Because of the inherent energy inefficiency of these units very few manufacturers still make them. Swegonair, the manufacturers of the original ActionAir units installed at Canary Riverside, no longer make FCUs with electric heating elements.
Safety features
Numerous safety mechanisms are built in to the FCUs to prevent fires/spread of fumes in the event of a fire. The heating element will only come on if there is sufficient air flow passing over them. This is controlled by a differential pressure switch, which measures air pressure inside and outside of the FCU. A faulty DPS will prevent the heating element from coming on, resulting in the FCU blowing out ambient air. The DPS has a limited lifespan because the rubber diaphragm perishes over time.
If a smoke alarm is activated in your apartment it will cause the FCU to switch off. This is to prevent the spread of smoke/fumes, and/or turn off an overheating FCU. Smoke alarms are located in the ceiling voids next to the FCUs.
Hager timer
A Hager timer unit that overrides the Baxi FCU control is located in the electrical distribution box (usually located in your hall cupboard). You can find instructions for the unit here. If the Hager unit is set to the 'O' position the FCUs will not run - even if the green light is on on the Baxi unit.