Smoke Test before using a Flue Gas Analyser
Before commissioning or servicing an oil-fired heating appliance, it is important to perform a smoke test by taking a sample of the flue gases from the boiler flue before using an electronic flue gas analyser. Failing to carry out such a test may result in temporary or permanent damage to the flue gas analyser’s internal components including the oxygen and carbon monoxide sensors.
A smoke test can be accomplished using a smoke test pump and filter paper. To prevent condensation of the flue gases, first warm the smoke test pump body. To obtain a sample of flue gas, insert a clean piece of filter paper into the smoke test pump slot and tighten the clamp.
Take a Sample of the Flue Gases
After the heating appliance has been operating for approximately ten minutes, place the sampling tube of the pump into the test point on the heating appliance flue whilst been careful not to make contact with the internal surfaces of it. This could cause carbon deposits (soot) to enter the sampling tube and produce a smoke spot that provides an incorrect reading.
Check the Smoke Count
Pump the smoke test pump evenly ten times to obtain a sample of the flue gases through the filter paper. Remove the filter paper and compare the smoke spot produced on the filter paper with the smoke count chart provided with the pump. Adjust the burner’s air damper so a smoke count of no more than two is obtained and repeat the test until the desired result is achieved.
Water Vapour Present
If the air damper on the burner is opened excessively then this may produce a wet spot on the filter paper. This wet spot is caused by water vapour within the flue gases that is caused by too much excess air. Simply reduce the amount of air and re-test until there is only a trace or a smoke count of one is achieved.
Consult Manufacturer’s Data
If in the event that the smoke count will not reduce then, if possible, observe the burner flame for instability, misshape or impingement. Recheck the burner’s oil pump pressure against the burner manufacturer’s data and if necessary, replace the burner nozzle with a new burner nozzle to the correct spray angle, flame pattern and output as indicated by the burner manufacturer.
After a satisfactory smoke test, a flue gas analyser can now be used to complete the combustion efficiency testing of the heating appliance.
Electronic Smoke Test Pump
The manual measurement of a smoke count using a smoke test pump, as described above, can be complicated and time consuming. However, with the introduction of the electronic Testo 308, this process has become faster whilst not compromising the accuracy of a smoke test. This instrument will definitely compliment the range of tools, including the flue gas analyser, used by a heating professional in the oil-fired heating appliance industry.
CPA1 Combustion Performance Analysis of Domestic Appliances
Within the UK are the approximately 120,000 registered gas service engineers and some 45,000 use a flue gas analyser. Despite 75,000 gas service engineers holding competency in HTR1 (gas fires) and CEN1 (central heating boilers), they do not possess an assessed competence in the operation of flue gas analysers. It will shortly become a requirement for all gas service engineers to correctly operate a flue gas analyser. The introduction of the CPA1 Combustion Performance Analysis of Domestic Appliances is a gas safety course and assessment designed specifically for gas service engineers for compliance with the requirements of BS7967 Parts 2 to 4.
Safe Operation of a Heating Appliance
Alarmingly, it is becoming a quite common story of deaths caused by carbon monoxide (CO) poisoning because of incorrectly operating or dangerous conditions of heating appliances within dwellings. Therefore it is imperative that gas service engineers are able to competently check the safe operation of a heating appliance after installation or during a service call. This has led to the government to legally require that all gas service engineers are certified in the understanding the proper and safe use of a flue gas analyser.
Operating a Flue Gas Analyser Effectively
Unfortunately, a vast majority of gas service engineers are unaware of the full potential that a flue gas analyser has to offer or indeed how to operate the equipment effectively – a common mistake is simply failing to select the required operating mode on the flue gas analyser for a particular type of fuel. From February 2010, all gas service engineers completing or holding HTR1 and CEN1 will be legally compelled to complete their CPA1 first.
CPA1 Course and Assessment
The Combustion Performance Analysis of Domestic Appliances course and assessment comprises of:
- Commissioning, servicing and testing appliances requirements when new components have been installed
- The Gas Industry Unsafe Situation category given to gas appliances that do not reach a satisfactory combustion performance
- Allowances made for gas cooker carbon monoxide (CO) levels
- Comprehension of action levels for gas appliances
- Remedial action required if carbon monoxide (CO) / carbon dioxide (CO2) ratio levels continue to be above suitable performance levels after adjustment
With the introduction of the CPA1 flue gas analyser assessment course, which is ratified by the Approved Certification Scheme (ACS), both the government and the heating industry have implemented necessary action to provide gas service engineers with a thorough understanding of combustion performance gas analysis required for commissioning at installation, re-commissioning after servicing or replacement of parts or the recognition of full service requirements on gas-fired appliances listed in BS 7967 Part 3 2005 Guide.