Commercial Boilers, Heating & Hot Water
Commercial Flue Systems
Commercial boiler flues are crucial as a part of boiler installation, and there is a skill to selecting the right flue and installing it properly to aid performance and help to keep your employees safe.
Boilers that have a rating of 70kW or higher are classed as commercial, and therefore need a commercial flue, and this brings with it a responsibility for employers to take safety precautions.
What is a Flue?
A flue is a vent or passage that allows exhaust gases or smoke from a heating system or other combustion process to escape safely to the outside atmosphere. It is typically a duct or pipe that runs through a building, leading from an appliance that produces the exhaust to the outside air. Flues are found in various types of heating systems, including gas or oil-fired boilers, water heaters, and fireplaces. They are designed to prevent the buildup of harmful gases, such as carbon monoxide, within the building and ensure that the air inside remains safe and breathable. Proper installation, maintenance, and inspection of flues are crucial to ensure they are functioning correctly and safely.
Some people may use the word “chimney” when they mean flue. In terms of a commercial boiler flue, the chimney is the shaft which is home to the flue itself, so it is important to get the terminology right.
Types of Flues
There are various types of flue systems that may be suitable for your business.
- Twin All System Chimneys are suitable for high positive pressure systems and both condensing and non-condensing appliances. They have a pre-installed installation and consist of metal walls in a concentric design.
- Single Wall Chimneys are used on multi-fuel applications and serve as a connecting flue pipe on both non-condensing and condensing applications.
- Flexible Liners are an option to reline existing chimneys and avoid the cost of replacing the whole flue.
Commercial Boiler Flue Regulations
Like many other aspects of your commercial building, the commercial flue has certain regulations that apply. When you work with Robinsons Facilities Services engineers you can ensure that you are getting adequate advice from accredited professionals. We’re always happy to advise on your flue system and what you need.
There are regulations regarding the flue and the chimney within which it is housed. “The Construction Products Regulations” are crucial to the flue, and this means that you must consider the following:
- The flue must come with a CE mark to prove that it has met the stringent standards of the EEA.
- It must be rated to deal with high temperatures, up to 400 degrees for multi-fuel boilers and 200 for oil or gas boilers.
- The boiler must be built to be corrosion resistant, even when dealing with the products of the boiler combustion process.
- The flue must be adequately lined too, and able to withstand the products of combustion.
- It must be able to allow condensate to drain freely, making it condensate resistant.
- The flue must be at a level where it is resistant to soot fires, and it must also be placed away from potential fire hazards such as gas supplies or timber.
Additional considerations should also be taken into account, for instance, ensuring that the chimney and flue reach an adequate discharge height, which means they can reduce their emissions in a way that doesn’t cause a risk to the health of the general public and those outside the building.
The commercial flue installation must also be straight, avoiding bends that can impact the performance, and it must also be easy to access as it will need to be cleaned and maintained. Also, the joints must allow for regular testing and planned preventative maintenance such as inspection or leakage testing. Flue maintenance is another service that our team can offer to ensure you remain legally compliant.
Getting your commercial flue systems perfectly installed and maintained is vital, and making the wrong choice can even be a risk to health, which is one of the reasons for commercial flue regulations.
There are many potential flue problems. Blockages may cause exhaust gases from escaping safely. This can lead to a buildup of harmful gases, such as carbon monoxide, within the building. Corrosion is also possible, as over time, flues can wear away as they are exposed to moisture and acidic exhaust gases. This can lead to leaks or holes that can cause dangerous gases to enter the building.
If you would like to learn more about commercial flue systems or any of our other services, please get in touch with us today. The expert Robinsons Facilities Services team would be happy to discuss your needs and provide a tailored solution for your business, and provide maintenance services as well as installation of commercial flues.
Robinsons Facilities Services are experts in a variety of heating solutions and work with businesses across Yorkshire and the North of England. Contact us today for all planned, reactive maintenance or emergency call out. Call 01423 226578 or get in touch to see how Robinsons Facilities Services can help.
Commercial Flue System Maintenance FAQs
There are some rules regarding boiler flues, which need to be a minimum of 75mm below any material that has the potential to be damaged by heat, and over 150mm to the side of vertical drains.
You should ensure that whoever is fitting your flue has the required training and certification, which means most people are not able to fit their flue.
The flue should comply with the rules of The Construction Products Regulations, meaning the flue itself needs a CE mark and a high temperature rating in order to be suitable for use.

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