Why clean the ventilation system?

In the closed internal environment of a large modern yacht, the cleanliness of its ventilation system is paramount in maintaining this environment in a healthy condition. Adverse health effects associated with contaminated air supplied by ventilation machinery and ducting in a poor and dirty condition are well documented. The efficiency of a dirty ventilation system is also compromised, the design parameters are not met and the system becomes unbalanced. Expensive furnishings, panels, curtains and carpets can also be stained by dirt and mould emitted from a dirty ventilation system. A dust-lined duct is also the perfect conduit for the spread of fire. The importance of maintaining the extract system free from dust and debris is often overlooked. Apart from an unhealthy back draught of polluted air if the system is turned off for whatever reason, if the inlets are blocked with dust and debris then the efficiency of the whole system is compromised, the yacht cannot ventilate as per design and fresh air changes do not take place as frequently as is required. A grease-laden galley extract duct and fan presents a serious potential fire hazard. Current regulations are addressing the importance of maintaining the galley extract system in a clean condition. Similarly, a laundry dryer extract duct blocked with dust and debris also presents a fire hazard; a dryer that cannot vent properly can overheat and ignite the "wick" of dust and fluff that caused the problem.

Click to enlarge Who needs the ventilation system cleaned?

All yachts require a regular ventilation system cleaning and preventative maintenance program. New yachts have their systems fitted in the yard before surrounding metalwork, carpentry, painting, varnishing and other finishing work is carried out. All of these activities create dust that will enter ventilation ductwork. Although the system was clean when it was fitted, by the time the yacht's owner takes delivery the ventilation system will be contaminated with sawdust, metal fillings, carpet fluff and other debris. There is no point in beginning a filter maintenance program if ductwork is already contaminated beyond the air handlers. Modern yachts have a busy schedule and evermore-complex control and electronic systems that do not allow the engineer to spend time on maintaining and cleaning air handlers and fan coil units. No matter how well filter maintenance is carried out, dust inevitably finds its way into the air supply system; added to this is debris from corrosion, degraded insulation and worn fan belts. This, together with the moist environment created by a sea -air supply, provides an ideal breeding ground for mould and bacteria inside air handlers, fan coil units and ducting. Air, forced over these growths, carries them throughout the system and into the internal environment of the vessel, an obvious health hazard for those breathing the internal air. From experience gained and feedback from yacht engineers, we recommend that a ducted or fan coil system be cleaned and decontaminated every two years in order to maintain the system in a healthy and efficient condition. Laundry and galley extract systems, which generally work almost non-stop on a busy yacht, will require an annual cleaning to remove a potential fire hazard.

Will cleaning the ventilation system damage the yacht's interior?

Working aboard luxury yachts requires an awareness and respect for the expensive furnishings and fittings found aboard these vessels. Many yacht owners are concerned about damage that may be done to their yachts when contractors are permitted to work in the interior of the vessel. For this reason, we have always operated with the same small team of trained and experienced technicians who, apart from having an in-depth knowledge of ventilation system cleaning, are accustomed to working tidily and with great care aboard luxury yachts. All delicate areas are fully protected before work commences and all dust and debris is collected in a high-volume vacuum collection machine so that no area within the yacht is re-contaminated.

How is the cleaning carried out?

General: Access for cleaning ducting is normally achieved through inlets and outlets or by cutting access in the duct walls where required. Industry standard access doors are then fitted. These are thermally insulated, quick- release doors that provide easy access for future cleaning and system inspection. To clean ducting we use an electrical rotary brushing cable that can be fitted with a variety of brush-heads. On smaller peripheral ducting a high- pressure air wash system is used. Both methods are industry standard, although some of our equipment has been customized to work specifically on yacht air ducting. A high-volume vacuum collection machine is used to direct and collect the dust and debris dislodged. All variable dampers are marked prior to cleaning and reset; this ensures the system stays balanced. Sensors are protected and fire dampers and turning vanes are checked and cleaned individually. De-graded or mouldy insulation found within air treatment units or supply outlets is either replaced or coated with an anti-microbiological growth coating, specially formulated for use in air-conditioning systems. The components of the system are treated individually as follows:

The Air handlers: All air handlers will be opened up, thoroughly vacuumed out and the fan, heating elements and chiller units blown clean with compressed air. Where it is deemed necessary, the fan will be removed for a thorough cleaning and to gain access to any plenum box beyond the fan. An access panel may also be cut in any plenum box where necessary. The fan bearings are checked and can be replaced if required. All internal surfaces of the handler will be wiped with a disinfectant/detergent and any damaged insulation repaired or replaced. Any rust found will be treated with a water-based rust converter or other approved marine-quality anti-corrosive paint. The filter will be changed and the fan belt checked for correct tension or wear. To finish, the handler is sprayed with an air-conditioning system biocide.

The Supply Ducting: The supply ducting throughout most of the boat can normally be accessed for cleaning from the inlets at the air handler and through the individual outlets. However, where the outlet is through a linear grill or there is mixing box at the end of the duct, then deckheads will have to be dropped to achieve access. When plans of the ducting layout are available, then the ducting will be accessed where necessary to clean ducting not reached from the outlets. All outlet grills are cleaned and disinfected; these are normally found covered in mould.

The Fan Coil Units:
A lot of the work involved in cleaning fan coil units is gaining access to them. Usually furniture has to be removed, cupboards dismantled or panels unscrewed etc. Once accessed and opened up, each unit will be treated as for the air handlers. The ducting supplying each unit will be cleaned. The duct between the inlet and outlet of the unit will also be cleaned; this we have generally found to be full of mould growing on the duct walls. On each fan-coil unit the chiller, fans, motor, electrics and all internal areas are blown clean with compressed air, vacuumed out and all surfaces wiped with a disinfectant. Particularly dirty fan blades are scraped and wire- brushed to remove all mould and debris. Drip trays will be cleaned. All filters changed. The inlet and outlet grills will also be cleaned. Damaged or mouldy insulation found within the unit will be replaced or repaired. Finally, the unit will be fogged with an A/C system biocide.

The Extract System: An extract system clogged with an accumulation of dust and debris is very inefficient and will not extract the volume of air that it was originally designed to do. Fan blades clogged with dust do not perform efficiently. All bathroom and general extract ducting will be cleaned with the rotary brushing cable, as for the supply ducting. Inlet vents are cleaned and disinfected. All extract fans will be cleaned with compressed air and particularly dirty fan blades scraped clean. Fan belts and bearings are checked and replaced as required.

The Galley Extract: An extract duct lined with grease is a breeding ground for bacteria. If grease is allowed to build up, a backwash of foul smelling air is often noticed in the galley. More importantly, having air forced over a tube lined with a supply of easily inflammable fuel (grease), is an obvious fire risk. The galley extract duct will be accessed wherever possible by cutting apertures in the duct wall. Installing approved access doors or, where space does not permit this, fitting steel plates sealed with high-temperature resistant sealant, closes these apertures. Once accessed, the duct is de-greased by hand. This involves a combination of scraping, scouring and wiping with non-corrosive degreasers. A small steam cleaner will also be used where necessary. Hard to access areas are cleaned with the rotary brushing cable fitted with special nylon coated wire brush-heads to remove caked- on grease. The galley extract fan will be removed (if possible), disassembled and thoroughly cleaned. All surfaces of the galley hood are usually given a thorough de-greasing and any external stainless steel surfaces are polished.

The Laundry Dryer Extract: An extract duct clogged with dust and fluff does not allow the dryer to exhaust hot air efficiently. An overheated dryer can ignite the fuse of combustible fibres within the extract duct. The filters in the dryers will be removed and the area behind them and around the drum vacuumed out. The fan in the dryer will be blown with compressed air to remove all dust. The backs of the dryers will be removed, enabling the fan motor and heating element to be blown clean with compressed air. Pulling out the dryers will access the ducting system, which will be cleaned along its length as far as its outlet. Any other extract fans associated with the system will also be cleaned.

On Completion Of The Job

Much of the work that we carry out on ventilation systems goes unseen, for obvious access reasons, by those sanctioning or paying for the work. The yacht's engineer will also want to know what was carried out for his maintenance records. We therefore consider it important that the work is recorded with photographs and written details. A full written report, with before and after photos recorded on a CD-rom, is therefore presented to the yacht's captain on completion of the work. This report will detail the state of the systems before and after cleaning, details of work carried out, locations of installed access panels for future reference and any recommendations as to future cleaning schedule and improvements that could be made to the systems.

c/Lirio, 70
07181 Marratxi

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