Troubleshooting
Combi Boiler Losing or Low Pressure
A pressure gauge that won't stay up is telling you something.
Most combi boilers operate around 1–1.5 bar when cold. If the needle sits low or keeps falling, the boiler may reduce output or lock out. A one-time drop after maintenance is normal; repeated loss almost always means water is escaping somewhere.
Topping up via the filling loop is something many homeowners can do per their manual — but a system that keeps losing pressure needs a technician to find the leak or check the expansion vessel.
Why pressure drops
- A small leak in pipework, a radiator valve or a fitting
- A failed or waterlogged expansion vessel
- A weeping pressure relief valve
- Air recently bled from radiators
- A leaking heat exchanger (serious — needs prompt attention)
This is not a DIY repair
Combi boilers are gas-fired appliances regulated under the BC Safety Standards Act. Opening the unit, touching the gas valve, or working on the flue without a valid BC gas-fitter licence is both unsafe and illegal. Diagnosing the fault is helpful — fixing it should always be left to a certified technician.
Call 778-909-5731Frequently Asked Questions
Related symptoms & help
Talk to a Licensed Combi Boiler Specialist
Free, no-obligation quotes across Greater Vancouver. CombiBoiler.ca — A division of ROMA Heating Ltd..