The importance of fan coil unit maintenance together with regular ductwork cleaning cannot be stressed too highly when you consider that a failure to keep coils clean or simply replace air filters can increase operating costs by as much as 25%. That’s before you start to take in to account any reductions in heating or cooling performance, the inconvenience of increased breakdowns, higher reactive maintenance costs, and the impact on indoor air quality and the health and wellbeing of building occupants.
What is a fan coil unit?
A fan coil unit (FCU) is a simple mechanical heat exchanger used in heating, ventilation and air conditioning (HVAC) systems serving commercial, institutional, industrial and residential buildings. The units are designed to provide heating, cooling or both to closed indoor environments. The primary components include a coil or heat exchanger, an air filter and a fan, some units may also incorporate a drip tray and interior liner.
These units can be suspended from the ceiling, and these are usually referred to as horizontal installations. Other installations, where the fan coils are wall mounted or located on the floor, are called vertical units. However they are installed, you will most commonly find fan coil units fitted in areas where there is a need to control internal temperatures. They are a popular form of heating and cooling in offices, shops, hotels and residential accommodation, and are sometimes used to supplement other, larger HVAC and climate control installations.
How do fan coil units work?
One of the main benefits of these units is that it they can be used to heat or cool the space in a single room as a standalone unit, or be connected using ductwork to heat or cool several internal spaces at once.
Poor fan coil unit maintenance can increase operating costs by as much 25%
Fan coil units incorporate a chilled water coil for cooling and either a hot water coil for heating or an electric heating element. Temperature control is usually achieved by using either an automatic thermostat, or a manual on/off switch.
Depending on the type of installation, some fan coils draw air from outside. However, many fan coil units are not designed to treat air from outside, and therefore do not have a way of controlling the amount of outdoor air drawn in.
During the winter months, if the external temperatures drop significantly, the heat exchanger coils need to be protected from freezing. During hotter weather, the coils might also struggle to cope with increased humidity in the atmosphere.
Fan coil units are really only designed to heat or cool the indoor air rather than clean or control humidity. Even though drawing in air from outside is often quoted as a selling point for some fan coil units, it can sometimes do more harm than good.
If a fan coil unit draws in fresh air from outside, it will usually have an air filter fitted to both the intake for outside air, and on the entry point for recirculated air. It is the job of these filters to prevent insects, vermin and any particles of dirt or debris entering the internal spaces.
The importance of fan coil unit maintenance and regular cleaning
Failing to maintain fan coil units in good condition can lead to a number of problems including increased energy costs, poor heat transfer efficiencies, reduced reliability and higher maintenance. If dirt, debris and other contaminants are allowed to accumulate on surfaces inside the units or ductwork problems can occur including:
The recommendation is that fan coil unit maintenance in both business and home environments is carried out regularly to ensure the units are both efficient and reliable. They should be professionally inspected and thoroughly cleaned and serviced before the summer and winter seasons start each year. Disinfection of the fan coil units and distribution duct-work should be also carried out where necessary.
Other problems to be considered
One common problem with older fan coil units is unsightly black flakes blowing out of the air vents of the unit. This is usually caused when the interior liner of the unit breaks down through either damage or age. When we refer to the liner, we mean the internal blanket which is fixed to the casing of the unit. Its main job is to reduce noise levels. The most commonly used type of insulation is fibreglass, with a black liner.
There are two approaches for resolving this problem. First, during the fan coil unit maintenance programme, clean out the unit and the interior duct-work and seal it to totally enclose the liner.
Alternatively, remove and replace the old or damaged liner with a new one. This is the more expensive option, and it also takes longer to complete the work.
The lifespan of an internal liner used in fan coil units varies greatly. In some situations, it might need to be replaced in as little as 8 years. Usually however, you can expect the liner to last for 20 years or more. There are a number of factors which have an effect on the lifespan of the fan coil unit liner and these include temperature, maintenance frequency and humidity levels.
What’s involved in fan coil unit maintenance and cleaning?
When fan coil unit maintenance and cleaning is required in commercial, institutional and industrial environments it is usually good practice to get the professionals in, especially where cleaning of larger fan coils is required. The equipment typically used to do the job includes a strong vacuum cleaner and compressed air. Specialist cleaning products, detergents and disinfectants may also be required to complete the job properly.
It’s a good ideal to have a formal programme of regular light cleaning of the units, duct-work and controls. This would typically involve vacuuming and dusting off the fan coil itself, the housing and motor, and as much of the liner as is accessible. Checking the condensate drip trays and any drains for blockages, and cleaning them using a good disinfectant is also highly recommended, as is checking other components such as drain fittings, drip lines and ducting. Replacing air filters, and giving the external surfaces of the units a good clean too.
If you keep on top of the regular maintenance and light cleaning activities then you won’t have to tackle a heavy deep-clean as frequently. A deep-clean typically involves everything in a light clean, but might also involve using compressed air and high-powered vacuums to clean out ductwork and air registers. The use of cleaning products, specialist degreasers and air hygiene biocides may also be required which will help to maintain system performance, effective air flows and good indoor air quality.
What types of contamination can affect fan coil units?
It’s probably important to define what we mean by contamination when discussing fan coil unit maintenance and cleaning activities. Contamination in this context could be grease, fats from cooking, organic debris, salt, scale from hard water, rust and much more. These types of contamination will often have different pH measurements from acidic to alkaline. It’s therefore very important to know what type of contamination you are dealing with in order to select the right type of cleaner to treat it correctly without damaging the fan coil units and other HVAC components.
Usually, types of contamination are classed into four main groups:
Most commercial cleaning products designed for fan coil unit maintenance cleaning are either strongly alkaline or acidic. Such products can be used (with care) by specialist cleaning and maintenance companies undertaking a system deep-clean, to help shift the build-up of fats, greases and other contamination. However, these cleaning products are not really intended for use on a regular basis – they’re just too harsh and can cause significant damage if used incorrectly. Short term, they might make your fan coil units appear shiny and spotless. However, they can also strip the coating from the aluminium coils, which makes them liable to further deterioration, reduce efficiencies and shorten life-cycles.
Professional fan coil unit servicing
It’s often the sensible option to get the professionals in to carry out fan coil unit maintenance and cleaning. However there’s much that home and business owners can do to keep their units performing well. Replacing the air filters is a straightforward task, and should be done every three months as a minimum. Some homeowners change the air filter monthly depending on their circumstances. Keeping the areas around the fan coil units free from dirt, dust and debris will also have a huge impact on the amount of dust which accumulates and the frequencies for fan coil unit maintenance and cleaning operations.
Specialist HVAC and air hygiene solutions
WTS offer a range of specialist fan coil maintenance and ductwork cleaning solutions to help businesses maintain their HVAC installations to ensure workplace environments are safe and operate at peak performamce.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained technicians and engineers we can offer specialist environmental management solutions to businesses throughout the UK and Internationally.
Contact us today to learn how our expert air hygiene solutions can help you.
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