OFTEC Commissioning and Servicing 2 — Questions and Answers
Question 1: What are the key checks included in an annual oil boiler service?
- Combustion analysis, heat exchanger inspection, flue integrity, oil supply, controls, and safety devices (Correct answer)
- Only checking the oil level in the tank
- Only cleaning the outside of the boiler
- Only replacing the filter
Correct answer: Combustion analysis, heat exchanger inspection, flue integrity, oil supply, controls, and safety devices
A comprehensive annual service includes: combustion analysis, heat exchanger cleaning and inspection, flue gas spillage test, nozzle replacement (as needed), filter cleaning/replacement, safety device testing, oil supply checks, and controls verification.
Question 2: Why should the oil nozzle be replaced during a service, even if the burner appears to be working well?
- Nozzles wear over time, changing the spray pattern and degrading combustion before problems become obvious (Correct answer)
- Nozzles never wear out
- New nozzles are cheaper than old ones
- It is only done to generate revenue for the technician
Correct answer: Nozzles wear over time, changing the spray pattern and degrading combustion before problems become obvious
Oil nozzles erode gradually from the high-pressure oil flow, changing the spray angle and flow rate. This degradation occurs before any visible symptoms appear. Replacing the nozzle annually (or as per manufacturer guidance) maintains optimal combustion.
Question 3: What should be inspected when examining the heat exchanger during a boiler service?
- Soot build-up, signs of corrosion, cracks, and any evidence of water leakage (Correct answer)
- Only the outside colour
- Only the serial number plate
- Nothing — heat exchangers are sealed units
Correct answer: Soot build-up, signs of corrosion, cracks, and any evidence of water leakage
The heat exchanger must be inspected for soot accumulation (which reduces efficiency), corrosion (which could lead to CO leakage), cracks (which are a CO hazard), and any signs of water leakage from the waterways side.
Question 4: What is the purpose of cleaning the photocell during an oil burner service?
- Soot or deposits on the photocell can prevent it from detecting the flame, causing nuisance lockouts (Correct answer)
- The photocell does not need cleaning
- Cleaning makes the photocell brighter
- It improves the oil flow rate
Correct answer: Soot or deposits on the photocell can prevent it from detecting the flame, causing nuisance lockouts
The photocell (flame sensor) detects flame by sensing UV or visible light. If the lens becomes coated with soot or oil deposits, it cannot detect the flame properly, causing the control box to lock out even though a flame is present.
Question 5: When servicing an oil boiler, what condition of the ignition electrodes would require replacement?
- Cracked porcelain insulation, heavily pitted or eroded tips, or carbon build-up bridging the gap (Correct answer)
- Slight discolouration is sufficient reason
- Electrodes never need replacing
- Only replace if the customer requests it
Correct answer: Cracked porcelain insulation, heavily pitted or eroded tips, or carbon build-up bridging the gap
Electrodes should be replaced if the porcelain insulator is cracked (causing short circuits), tips are heavily eroded (weak spark), or carbon deposits bridge the electrode gap (preventing spark). Otherwise, clean and re-gap to manufacturer specification.
Question 6: What is the correct procedure for priming an oil burner after the system has run out of fuel?
- Loosen the bleed screw on the pump, run the burner to expel air, then tighten when oil flows steadily (Correct answer)
- Pour oil directly into the combustion chamber
- Hit the pump with a hammer
- Let the system prime itself over 24 hours
Correct answer: Loosen the bleed screw on the pump, run the burner to expel air, then tighten when oil flows steadily
After refuelling, air must be bled from the oil supply line. Loosen the bleed screw on the fuel pump, operate the burner (it will lockout), and air will be expelled. When pure oil flows from the bleed screw, tighten it and reset the burner.
OFTEC Commissioning and Servicing 2
What are the key checks included in an annual oil boiler service?