Expansion Vessel Replacement
Restore stable boiler pressure across Greater Vancouver
The expansion vessel (also called an expansion tank) absorbs the increased water volume that occurs when your combi boiler heats the system. It maintains stable pressure by compressing an internal air bladder, preventing your pressure relief valve from opening every heating cycle.
When the expansion vessel fails — typically due to a ruptured bladder or lost air charge — you'll notice pressure gauge fluctuations, relief valve dripping, or the boiler cycling on and off frequently. Our licensed technicians can diagnose and replace a faulty expansion vessel across Greater Vancouver.
What You Need to Know
Expansion vessels are pre-charged with air on the bladder side. Over time, the bladder can rupture or the air charge can leak, causing the vessel to become waterlogged and ineffective. This puts excess stress on system components and triggers the pressure relief valve.
A properly sized and functioning expansion vessel is essential for safe boiler operation. We match the replacement vessel to your system's volume and the manufacturer's specifications.
- Symptoms: pressure gauge bouncing, relief valve dripping, boiler short-cycling
- Inspected as part of annual boiler maintenance
- Must be properly sized for your system water volume
- Installation includes air charge set to system pressure
Our Service Process
- Check system pressure and expansion vessel air charge
- Confirm vessel failure by isolating and testing the bladder
- Select a correctly sized OEM or equivalent replacement vessel
- Drain system, remove old vessel, and install the new one
- Set pre-charge pressure to match system fill pressure
- Re-pressurize system and verify stable operation
- Check pressure relief valve for proper function after repair
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
Talk to a Licensed Combi Boiler Specialist
Free, no-obligation quotes across Greater Vancouver. CombiBoiler.ca — A division of ROMA Heating Ltd..