Combi Boiler Troubleshooting
Find your symptom below to understand the likely cause, what's safe to check yourself, and when to call a licensed gas technician.
Combi Boiler Producing No HeatThe boiler is on but your home stays cold — here's what's usually behind it.Combi Boiler No Hot Water (Heating Works)When the radiators warm up but the taps run cold.Combi Boiler Losing or Low PressureA pressure gauge that won't stay up is telling you something.Combi Boiler Pressure Too HighWhen the gauge climbs into the red.Combi Boiler Leaking WaterAny water where it shouldn't be deserves attention.Combi Boiler Making Unusual NoisesBoilers are quiet when healthy — new noises are clues.Radiators Not Heating EvenlyCold spots usually mean air or sludge, not a broken boiler.Combi Boiler Keeps Shutting OffA boiler that won't stay running is protecting itself from something.Combi Boiler Pilot Light or Ignition Won't Stay LitMost modern combis use electronic ignition — but the symptoms are similar.Frozen Condensate PipeA common cause of winter boiler lockouts in BC cold snaps.Combi Boiler OverheatingOverheat lockouts protect the heat exchanger — but the cause must be fixed.Boiler Not Responding to the ThermostatSometimes the boiler is fine and the signal isn't getting through.Yellow or Orange Boiler FlameFlame colour is a safety signal you should never ignore.Pressure Relief Valve Discharging WaterThe relief valve is doing its job — but something upstream is wrong.Smell of Gas Near Your BoilerGas smell is an emergency — safety first, diagnosis second.Weak Hot Water Flow From a Combi BoilerWhen the hot tap trickles but cold runs fine.Hot Water Temperature Keeps ChangingThe classic hot-cold-hot shower problem.Combi Boiler Display Is Blank or DeadNo lights, no display — start with power.Radiators Stay Hot When Heating Is OffHeat where you didn't ask for it points to a valve issue.Combi Boiler Tripping the ElectricsAn electrical trip is a safety signal — don't keep resetting it.Smell From the Boiler Condensate or DrainMost condensate smells are harmless — but rule out combustion issues.Boiler Won't Fire for Hot WaterThe burner ignores your hot tap.Low Pressure After Bleeding RadiatorsA normal side-effect of bleeding — usually an easy fix.Combi Boiler Short-Cycling (Firing On and Off)Rapid on-off cycling wastes fuel and wears components.No Heating But Hot Water WorksThe mirror image of the no-hot-water fault.Water Leaking From the Bottom of the BoilerWater under the boiler always deserves a look.