Maintenance is vital in burner efficiency
Failure to keep burners, used to produce heat in commercial buildings well maintained could lead to a potentially explosive situation according to Rick Crees
COMMERCIAL HEATING covers a wide array of business across the UK - from hospitals, prisons, schools and local authorities to name but a few. The one thing that they nearly all have in common is a burner, which is used to help produce their heat. They do so in an effective, efficient and reliable way, which is just as well, because the commercial industry spends a lot on heating. Taking the UK's healthcare sector as an example, it spends more than £400m per year on energy according to the Carbon Trust, which also states that if heating equipment is managed correctly it is possible to save up to 30 per cent on heating costs. That's a significant amount of money.
Of course, commercial businesses are actually obliged to tackle their heating costs. This is under the Carbon Reduction Commitment (CRC) Energy Efficiency Scheme, which is designed to improve the energy efficiency and cut emissions in large public and private sector buildings. The objective is to achieve an 80 per cent reduction in UK emissions by 2050. So there is plenty of work to do.
Burners can play a part in improving efficiency, but it's important to understand that efficient burner performance cannot be achieved without regular maintenance and service work. So what needs to be done to keep a burner in tip-top condition? Safety has to be top of everybody's agenda. Our service engineers are finding gas boosters which have not been installed or maintained in accordance with legislation. This is very bad news - it can lead to the failure of the bearing and fan units, and potentially an explosion. Certainly not the scenario you want in a public place like a hospital. Therefore all gas boosters must be inspected at least once a year and the fan bearing replaced every five years.
The fan bearing, and gas and drive seals are vital to a gas booster's safe operation. They need to be replaced at least every five years. It doesn't matter whether or not they are damaged - they still need replacing. Replacement will ensure the safe and efficient running of gas boosters.
If there is any damage to parts then they need to be replaced immediately. An increase in operational noise is one symptom of a damaged fan bearing - although not experiencing this does not mean a gas booster doesn't need servicing. An annual inspection will ensure safety.
Preventative burner maintenance is the most cost effective way of ensuring a burner is running at its most efficient. This also means business critical activities are not interrupted with any potential costly breakdowns. Before doing any maintenance work you must always switch off the electrical power and fuel supplies to the burner.
There is a list of criteria to ensure the continuing fault-free operation of the burner. They should be carried out every six months, and include: cleaning the working faces of the burner with a stiff brush. The fan impeller needs cleaning too because a dirty impeller will cause a dirty flame. All safety circuits need checking, as does the pressure against the values recorded when the burner was commissioned.
Ignition electrodes must be cleaned and checked for any damage. If they're cracked or worn they will need replacing. Any changes made in the control settings as a result of identifying and remedying fault conditions may require re-commissioning of the boiler. The oil nozzle plays a significant part in burner performance. Once it has completed 5,000 hours of operation it should be replaced with the same make, type and size as fitted. Failure to do so will alter the characteristics of the burner and may impair the performance and efficiency of the plant. So every month it's necessary to remove the nozzle from the oil lance and wash it in paraffin or something similar. The connection between the control motor and the valve needs to be checked twice a year. It may need to be tightened. Safety shutoff valves may also have come loose. They also need to be cleaned, repaired and replaced where necessary.
Combustion holds the key to burners. It is what improved burner performance stems from. It takes place when the carbon and hydrogen molecules in the fuel react with the oxygen molecules in air to form carbon dioxide (CO2) and water (H2O). Energy is released during the reaction. Combustion is able to minimise peak flame temperatures in a burner. This internal recirculation of furnace flue gases lowers the flame temperature and reduces emissions like carbon monoxide (CO) and nitrogen oxide (NOx).
When it comes to combustion air you need to check the plant room is well ventilated, while also inspecting the burner air inlet to make sure there is no obstruction to the air flow.
Products, technology, regulation and legislation change all the time. Therefore engineers need to be fully up to speed on how to maintain, service, fault-find and commission a burner. There are many factors to get to grips with - from understanding controls, combustion analysis, and the reasoning behind nozzle calculation, to getting the maximum potential in output, efficiency and longevity that a burner needs to be installed and commissioned correctly. So make sure you're fully up-to-date with the latest burner training.
//The author is the trading director at Nu-Way//
1 December 2013