Design is the key to effective ductwork maintenance

Ductbusters, duct cleaning
The key to a successful plan for cleaning ductwork is providing enough access doors.

Behind those duct access doors, and there are seldom enough, can lurk all sorts of horrors. Dermott Quinn shares his experiences as a specialist ductwork cleaner and makes recommendations on good practice.

As a duct-cleaning specialist working extensively in the public and private sectors we find that poor access — insufficient number of access hatches and doors fitted in the wrong place — are the most common issues our engineers face when they arrive on site to carry out routine maintenance. Engineers then face enormous difficulties in cleaning miles of ductwork which spread all around the building. The extra time it takes to carry out routine service projects all add cost for those who lease or own the buildings.

Whilst there are very clear guidelines on the position and number of access doors, time and again we see that these recommendations have been ignored. It leaves us with the impossible task of attempting to access ductwork to carry out essential maintenance work. In addition, although only access doors manufactured and installed to guidelines should be used, we often come across sub-standard equipment, such as patch plates.

To ensure that ventilation systems are simple to maintain, we have recently launched a design and installation service offering advice and consultation at the planning stages for new and replacement projects to create systems that are efficient and cost effective. We have always provided design and installation on request. As we have seen demand for this grow over recent years we have taken the decision to launch it formally and offer design and installation as a separate, additional service.

It is vital for businesses to keep their ductwork clean and the servicing up to date as so many are losing money unnecessarily through staff sickness and declining work rate due to dirty ductwork. Ventilation systems that do not work efficiently drastically reduce air quality — resulting in headaches, fatigue, loss of concentration and absenteeism for staff, yet companies are not doing enough to address the issue.

It is incredible that some businesses still invest so little in the maintenance of their ventilation systems when air quality has a direct effect on how their staff feel and perform at work. They may grumble about demotivated staff, but they should look at how long ago they cleaned and serviced their ventilation systems. They may think they are saving money, but it is a false economy.

Many facilities managers simply don’t think about air quality or its importance as an essential contributor to health and wellbeing in the workplace. Also, although employers have an obligation to their employees when it comes to the working environment, the only legal requirement regarding ventilation hygiene is that systems are regularly inspected and the findings recorded.

There is no legal obligation to clean, even though regular maintenance of ventilation and air conditioning systems is one of the measures recommended by Health & Safety Executive (HSE) to ensure employers fulfil their obligations to their staff when it comes to their working environment. However, when budgets are under pressure as they are now, it is too easy to put off what is essential cleaning work.

The issue is critical in public buildings, particularly hospitals where highly infectious diseases like MRSA and Clostridium Difficile can be carried through ventilation systems and also thrive and feed on flakes of dead, dry human skin that is a component of hospital dust and which can build up in ventilation ducts. Spores from mould which can thrive in ventilation ducts are a serious health hazard, and the debris that accumulates in ducts can propagate allergens and provide a breeding and feeding ground for insects and even vermin.

The installation guidelines for ductwork and ventilations systems are as follows.

Ductbusters, duct cleaning
Very few people see the inside of ductwork, but these shots of a dirty duct and a duct after cleaning tell a powerful story.

For normal-usage horizontal ductwork systems: access panels should be located at least every 10 m; at every turn; at every obstruction;

For kitchen extract systems: a maximum of every 3 m.

For vertical ductwork: minimum access opening at the top and bottom of each riser

Fitted on both sides on the ducting: heating/cooling coils; attenuators (rectangular); control dampers; filter sections; air-turning vanes; in-duct fans/devices.

Fitted on one side of the ductwork: fire dampers on; attenuators (circular); changes of direction.

These guidelines may result in more doors being fitted than originally intended. However, consultation with an HVCA-approved ductwork-cleaning company can often result in fewer doors being required.

The key message is that future servicing and maintenance should be top of mind when designing ductwork and ventilation systems. More time and consideration should be taken with the positioning and quantity of access doors fitted to ductwork systems in new and refurbished buildings.

Dermott Quinn is a director of duct-cleaning specialist Ductbusters.

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