Designers really need to pay more attention to access doors to allow ductwork to be cleaned effectively, says Ian Wall.
I would urge architects and contractors to take more time and apply more consideration to the positioning and quantity of access doors fitted to ductwork systems in new and refurbished buildings.

Lack of planning when designing the ductwork in a building can result in consistent losses of time and money over the life of the building.

Poor access caused by too few access hatches and doors fitted in the wrong place are the most common issues that Ductbusters engineers face when they arrive on site to carry out routine maintenance. Engineers then have enormous difficulties in cleaning miles of ductwork which spread all around the building. The extra time it takes to carry out routine service projects adds to the cost for those who lease or own the buildings.

While there are very clear guidelines on 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.


In order to ensure that ventilation systems are simple to maintain, my company has 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 and, 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.

There is also the issue of storing ductwork on site before it is fitted into the building.
There are guidelines and recommendations on how ductwork should be delivered and stored. While ductwork can be stored in its own dust-free surroundings to maintain its integrity, and there are industry guidelines on the storage of ducting during building work, dust will always get in and the ducting will usually have to be cleaned before the building is handed over however it has been protected.

Therefore, to save on costs, we suggest that, where possible, the ductwork is delivered to site in bulk and installed at the last moment and then cleaned just prior to handover. In our experience there is little point in shrink wrapping each piece or 'bagging off' ductwork at the end of each day to try and prevent dust and dirt getting in. It will always find a way.


Installation guidelines

The installation guidelines for ductwork and ventilation systems are:

For normal usage horizontal ductwork systems:
• Access panels should be located at least every 10m
• 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

This 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.

Tuxford and Tebbutt

Ductbusters was appointed by Melton Mowbray-based specialist cheese manufacturer Tuxford and Tebbutt for a ductwork cleaning and installation project.

The task included cleaning the ductwork in the maturing stores of the creamery, which dates back to 1780. The age of the building presented real challenges to the Ductbusters team who had to negotiate confined spaces and tight corners to service the ducting which had been installed around a host of nooks and crannies. They also had to work around the staff as the site had to remain open during the project.

Ductbusters also installed a new rigid ventilation system in the cheese production area, replacing the old, inefficient flexible system. Flexible ventilation creates a lot of resistance which cuts down airflow, but rigid systems improve airflow and reduce energy consumption. They are also simpler to clean giving the Ductbusters team an easier time when they are next called upon to carry out a routine service.

Ductbusters' sales director Ian Wall said of the project: 'The fact that the building was over 250 years old caused all sorts of problems because there were limitations when the ducting was originally installed. We took the opportunity of taking into account the future servicing of the ductwork when we replaced the old equipment, designing a system which would improve efficiency, but with the future maintenance in mind.'