Combi Boiler Maintenance Checklist

Monthly DIY Checks (Safe for Homeowners)

These checks take 5 minutes and require no tools. Do them monthly during heating season (October-March). If you notice anything unusual, call a licensed technician.

• Check system pressure gauge: Should read 1.0-1.5 bar when cold. If below 0.8 bar, top up via filling loop. If consistently dropping, you have a leak — call us
• Inspect visible pipework and radiators for leaks, damp spots, or rust stains
• Check condensate pipe (white plastic pipe, usually going to a drain): No blockages, no ice in winter
• Verify thermostat is working: Turn it up and confirm boiler fires; turn it down and confirm it stops
• Listen for unusual noises: Kettling (rumbling), banging, whistling, or grinding aren't normal
• Check CO detector: Test button monthly. If it alarms, evacuate, call 911, then call us
• Visually inspect flue terminal outside: No debris, bird nests, or vegetation blocking it
• Check for error codes or warning lights on the boiler display panel

Annual Professional Service Checklist

This is what we cover during every annual boiler service. These items require a licensed TSSA/BC gas fitter — do not attempt them yourself.

• Combustion analysis: CO, CO₂, O₂, excess air, and flue temperature measured with calibrated analyzer
• Electronic gas leak detection on all connections, valves, and fittings
• Burner assembly inspection and cleaning: ignitor, flame sensor, burner ports
• Heat exchanger inspection: Check for soot, scale, corrosion, or cracking
• Condensate trap and drain: Remove, clean, flush, and refill
• Expansion vessel: Check air charge pressure and diaphragm integrity
• System pressure: Check, adjust, and verify filling loop is fully closed
• Safety controls test: High-limit thermostat, low water cutoff, pressure relief valve
• Flue and venting inspection: Check for leakage, corrosion, blockage, proper termination
• Gas manifold pressure: Measure and adjust to manufacturer specification
• Ignition and flame sensing: Verify reliable ignition, flame rectification signal
• Circulation pump: Check for noise, vibration, and adequate flow
• Water quality: Test pH, inhibitor concentration, and check for sludge
• Thermostat and controls: Verify communication, calibration, and zone operation
• Written service report: Complete documentation of all readings, findings, and recommendations

Manufacturer Warranty Maintenance Requirements

Every major combi boiler brand requires proof of annual professional servicing to maintain warranty coverage. Here's what each manufacturer specifically requires:

• Navien: Annual service by licensed gas fitter. Records must be kept for warranty claims. 15-year heat exchanger warranty requires documented annual servicing
• Viessmann: Annual service required. Viessmann recommends using Viessmann-trained installers for warranty work
• Bosch: Annual inspection and service by qualified technician. Service records must include combustion analysis readings
• Rinnai: Annual maintenance by licensed professional. Warranty registration within 30 days of installation
• All brands: Service must include combustion analysis, gas leak check, and safety control verification at minimum

What Happens If You Skip Maintenance

Skipping annual maintenance has real consequences beyond voiding your warranty. Here's what typically happens to an unmaintained boiler over time:

• Year 1: Minor efficiency loss (1-3%). Slight soot buildup. No noticeable issues
• Year 3: 5-10% efficiency loss. Gas bills creeping up. Condensate trap beginning to clog
• Year 5: 10-20% efficiency loss. Soot and scale buildup significant. Burner starting to degrade
• Year 7: 15-25% efficiency loss. Heat exchanger stress increasing. Risk of CO production elevated
• Year 10: Heat exchanger failure likely. Boiler may be unrepairable. Full replacement needed — $6,500-$14,000

Frequently Asked Questions