Warning! This is for guide purposes only. It is only to be used by a competent Gas Safe Engineer.
The content below, provided on 4th November 2024, offers a guide to assist you in performing a boiler service with possible alternative outcomes. This guide is intended for informational purposes only, and we advise against interpreting the content as literal instructions.
Introduction to Bylaws and Regulations for Boiler Servicing
When servicing a room-sealed gas boiler, it is crucial to follow proper regulations to ensure safety and compliance. The following guide is based on key UK regulations that apply to room-sealed gas boiler servicing:
Gas Safety (Installation and Use) Regulations 1998 (GSIUR): Mandates that only Gas Safe-registered engineers may service or maintain gas appliances. It also requires servicing of room-sealed appliances as per the manufacturer's instructions.
Building Regulations Part J: Covers safe installation and operation of combustion appliances, including ventilation and flue requirements.
BS 5440-1: British Standard providing safety requirements for flueing and ventilation in room-sealed appliances.
BS 7671 (IET Wiring Regulations): Ensures electrical safety, particularly around live metal components near or within the boiler system.
Manufacturer’s Instructions: Always adhere to the servicing instructions provided by the boiler's manufacturer.
By following these regulations, you can ensure that the servicing procedure is both compliant and safe.
Initial Property and Service Information
Upon entering the property and greeting the customer, the initial steps include confirming the boiler location and availability of necessary documents.
Question
Response
Comments
Is a service manual available?
Is there any service history?
Boiler Location?
Are there any other gas appliances in the property?
Is this appliance in the same room as the boiler?
What type of appliance is it?
Service Type
What is your intention with this service request?
Is there evidence of the last service?
Date of Last Service
Is the gas capped or uncapped?
Prepare to follow the Reinstating Gas Procedures
Reinstating Gas Procedures
Notes: If the boiler has been isolated for precautionary reasons, such as requiring a service, you can proceed with reinstating the gas.
Notes: If disconnecting the meter union, ensure you use the earthing safety cable to bond any live metal components, both upstream (before the meter) and downstream (after the meter), to avoid static discharge.
If only a service is required and there is no downstream damage from the Emergency Control Valve (ECV), remove the blanking disc and reseal the meter connection.
To purge the gas pipe, open the gas connector furthest from the appliance and purge until you can smell gas. Use LDF (Leak Detection Fluid) on all joints. If the furthest point is the cooker, it may be favorable to purge via the cooker if it’s the most distant point and near the boiler.
After purging and completing the necessary checks, you can begin the 'Boiler Service'.
Boiler Safety and Operation Checks
Complete the safety and operation checks before proceeding with further service steps.
Question
Response
Comments
Is ventilation correct?
Is the flue flow satisfactory?
Does the boiler start up in hot water and heating mode?
Do the safety devices work?
Are the chimney terminals correct?
Any leaks, blockages, or corrosion to the flue:
Is the spillage test satisfactory?
Safe to Touch Test in accordance with BS7671
Verify that the appliance is isolated from the electrical supply and switch off all power to the boiler.
Using an approved voltage tester, test all accessible metal parts of the boiler, including pipes and casing, to ensure there is no residual voltage.
Check the integrity of the bonding by testing continuity between the boiler casing and the earth bonding point in accordance with BS7671 guidelines.
Use an earthing safety cable if required to bond metal components near live terminals, especially around areas like the gas meter and exposed pipes.
Complete a final continuity check on all bonding points, ensuring that any exposed parts are safely grounded.
Appliance Details
Type
Manufacturer
Model
Location
Serial No (if required)
Flue Type
Appliance Satisfactory Report
Please review the appliance and mark the appropriate responses.
Question
Satisfactory YES/NO
Comments
Burner(s)/Injector(s)
Ignition and flame picture
Heat exchanger
Electrical connection
Appliance/system controls
Fan(s)
Seals (appliance case, etc.)
Fireplace catchment space
Closure plate
Location and stability
Return air/plenum
Property and Compliance Checks
Is the accommodation rented? (Yes or No)
Type of work carried out - Service or Maintenance
Has a gas tightness test been carried out? (Yes or No)
If yes to the above, was this a Pass or Fail?
Is electrical bonding (where required) satisfactory?
Electronic Combustion Gas Analyser (ECGA) Readings
Has a full strip and clean service been carried out?
Initial ECGA reading:
Final ECGA reading:
Gas Pressure Checks
1. Let By Test: 7-10mb for 1 minute (0.25 acceptable).
If fails, check ECV for passing, then contact 0800111999.
2. Stabilization Test: 20-21mb for 1 minute, then test for 2 minutes.
On older appliances, refer to pages 6.6 table 6.5.
3. Slowly turn gas 'ON' and purge if gas pressure is below 7mlbs.
Purge through an appliance burner or by opening a union closest to the appliance until gas is detected, per 'Domestic Gas Safety On Site Guide'.
4. Record standing pressure (18.5 to 30mlbs).
mbrs
5. Check operating pressure by turning on hot tap (21mlbs +/- 2mlbs).
mbrs
Boiler Service Completion
Boiler servicing MUST comply with the current building regulations.
Since 15th June 2022, all new homes must produce 31% less CO2 emissions than previously allowed under the Part L building regulations.
1. Turn off power and gas to the boiler, unplug or remove the fuse, and lock up.
2. Isolate water to the boiler, including the flow and return on central heating.
If the flow and return valves do not turn off, drain down from the boiler and proceed.
3. Remove the boiler cover and place screws in a magnetic dish.
Ensure the seals on the boiler case are undamaged.
4. Check for any leaks, wear, and tear, and take notes.
5. Clean the heat exchanger using 50% water and 50% vinegar solution.
Use a spray bottle, scrubbing brush, and a thin instrument to clean between the coil elements. Rinse thoroughly to remove debris.
Before Cleaning - Upload Image:
After Cleaning - Upload Image:
6. Clean the probes within the heat exchanger.
Use a file rather than wire wool for better results to avoid damaging the probes.
7. Remove and clean the condensate trap.
8. Drain the boiler and pressurize the expansion vessel to between 0.8 and 1 bar.
Before replacing the dust cap, check for any passing air using LDF. A bent syringe can help in tight spots.
9. Close the drain point, reopen central heating isolation valves, bleed the system, and pressurize.
10. Turn the boiler back on and test by running the hot tap.
Use a gas analyser to check for CO levels using the CO Ambient test for ppm.
Has the boiler service been completed?
Heating Performance and Temperatures
1. Run the hot tap for 2 minutes and measure the gas rate
2:00
Gas Rate: m³/hr
Gross kW:
Net kW:
2. Check cold water temperature and litres per minute
Actual Boiler Output: kW
3. Check inlet gas valve standing pressure using a digital gauge
4. Final checks and measurements
2:00
Gas Rate: m³/hr
Gross kW:
Net kW:
Gas Analyses
1. Turn on the gas analyser and enter the customer’s details.
2. Set up the measurement site if not using default settings.
3. Place the analyser probe 150mm into the flue.
4. Turn the boiler on and activate test mode.
5. Measure low and high operating pressures.
6. Assuming the boiler has been running for 5 minutes by now start the time, then conduct the following tests.
10:00
7. Measuring CO and CO₂ levels in Low, High & hot water mode. The CO to CO₂ ratio should measure below 0.004, however, refer to MI's.
Low Heating Mode
High Heating Mode
Hot Water Mode
Low Heating Ratio:
High Heating Ratio:
Hot Water Ratio:
Calculation Explanation:
To find the CO/CO₂ ratio, we’re comparing the amount of carbon monoxide (CO) to the amount of carbon dioxide (CO₂) produced by the boiler. This helps us determine the efficiency and safety of combustion.
Measure the CO and CO₂ Levels: Begin by taking readings of CO (carbon monoxide, measured in parts per million or ppm) and CO₂ (carbon dioxide, measured as a percentage). These readings indicate the levels of combustion gases in the flue.
Calculate the Ratio: To get a meaningful ratio, divide the CO reading by the CO₂ reading, adjusting for scale. The formula is CO / (CO₂ × 10,000), which gives a value that helps us evaluate combustion efficiency.
Interpreting the Result: A properly functioning room-sealed boiler should have a CO/CO₂ ratio of 0.004 or lower. Ratios above this threshold may indicate incomplete combustion, possible air restriction, or other issues that reduce efficiency and increase emissions.
Maintaining a CO/CO₂ ratio at or below 0.004 ensures the boiler is operating efficiently and safely, reducing the risk of harmful CO emissions.
8. A recording of the natural air will need to be taken from by the window or the outside. Example (20.9%)
9. Conduct Integrity Sweep Test for CO (record in PPM)
2:00
10. Safety Device test: (Well runing the boiler, isolate the gas and listen out for a click).
Did the safety device activate?
Yes
No
Central Heating and Water Quality Checks
1. Central Heating and Water Quality Checks
Is there a central heating filter in the house?
Yes
No
N/A
Once filter has been cleaned, then continue to next step?
(Cleaned) Continue...
Outcome of the water quality test using the Sentinal Turbidity Tube:
2. Using the i-Test equipment and the app, perform a water test as directed.
Has the central heating for inhibitor and pH passed its test?
Inhibitor has been added to your central heating system.
Final Assessment
Safety Of Appliances
Is the appliance safe to use?
Yes
No
Complete a warning/advisory record and attach an appropriate warning label to the appliance/installation.
Unknown
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Boiler Materials
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Labour
hour(s)
half hour(s)
Labour Total: £0.00
Parts Subtotal: £0.00
Labour Subtotal: £0.00
Subtotal: £0.00
VAT (20%): £0.00
Grand Total: £0.00
Payment:
By signing this document, you confirm your satisfaction with the materials, parts, labour, call-out fee, and report. If you have any concerns or would like additional details added to the report, please request these before signing.