James R. Stringer
Background: The very first article I posted was on boiler combustion and the importance of complete combustion within a boiler. Unfortunately, building managers and owners may defer maintenance of boilers and try to avoid costs that they believe are not needed. In this post, we will see what happens when a combustion analysis is not completed for regular preventative maintenance and the effects of incomplete combustion over a period of time.
The first indication of incomplete combustion is black soot covering the flame sight glass. When performing the daily boiler checks, the building operator should always make a habit to check the flame while the boiler is firing. A general rule is that the flame should be bluish with a yellow tip. When the boiler is firing but you can’t see the flame, it is a good idea to de-energize the boiler and remove the flame sight glass to check for any soot build up. Make sure to let the boiler cool down!
Once we locked and tagged off the gas and electrical for the boiler, we removed the burner; lo and behold, the furnace was covered in soot. The soot drastically reduces heat transfer, causing energy costs to rise since more heat will exit through the stack/chimney rather than be absorbed by the water. There is also an increase in the chance of pollutants exiting into the atmosphere due to the incomplete combustion taking place. Soot can also cause the durability of a boiler to decrease over time as hot spots can develop and weaken the materials within a furnace.
Saying that: time to strap everything on and head in!
With the boiler being a confined space, we made sure that either Adrian (left) and myself (right) was present when one of us went inside of the boiler. We also limited our exposure inside the boiler to 10 minutes, ensuring we had numerous breaks and had a chance to rehydrate as it gets quite hot in the furnace of a boiler.
After manually brushing the inside of the furnace and cleaning all the soot off the walls of the boiler, we were hoping we could get by using a normal shop vacuum to collect the soot. This was not the case. In fact, we ended up having to sweep and mop the mechanical room a little more than we wanted to after that decision! After a couple more ideas to collect the soot, we decided to regroup and call it a day.
After some research, haggling, more research, more haggling, and applying what we had learned – we decided it was time to invest and purchased a Goodway soot vacuum to use at all our sites for true professional boiler cleaning that we will always have on hand. This made a huge difference.
After the lessons of the first day, we also upgraded our look.
The soot vacuum has a 20 gallon (76 litres) drum with increased horsepower, a reusable filter that can collect all the soot without it spreading; however, it does heat up very quickly and if left running for too long – it could trip off. Keeping the 10 minute rule while cleaning inside the boiler helped allow us to make sure the vacuum did not overheat between us taking turns entering the boiler. The hose brush attachment I had them throw in to the deal helped quite a bit as well!
After making sure we collected all the soot and disposed of it, we snapped some pictures and sent them off to the safety codes officer with ABSA for a quick review. Once we received the go ahead – we reinstalled the burner, checked all gas fittings for leaks, and installed a new low water cut off safety device since the old one became unreliable.
After everything checked out, we energized the boiler and had it firing. We then proceeded to test the low water cut off, high limit temperature switch, and then the flame detection device. No issues!
This boiler had a combustion analysis completed a few months before it was cleaned but we will have this boiler and the other two boilers on site have a combustion analysis completed in the following year when they are due to be inspected.
Conclusion: if a boiler is left unattended and regular preventative maintenance is not performed, it can have detrimental effects. This is just another example of maintenance that can’t be directly seen, so many believe that if it is out of sight, they can keep it out of their mind. However – by cleaning up this boiler and continuing to maintain it to this acceptable standard it has become much more energy efficient, environmentally friendly, and fundamentally much safer.
It is important to complete regular maintenance and of course try to complete as much as this maintenance in-house as possible. This is always an enjoyable experience for me as it lets me out of the office and get a break from the bookkeeping!
Bonus Picture!
(DC Comics and its legal team have repeatedly told me to stop sending them this picture and that I will not be the next Batman. I personally believe I pull the ‘half way clean from being covered in soot’ look quite well)