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Replacing the expansion vessel
• Isolate the boiler using the appliance isolation valves on the flow and return connections to the boiler.
• Remove the expansion vessel from the pipe work.
• Refit a replacement expansion vessel in reverse order using a recognised method of sealing the threaded
joint.
• Open the isolation valves, ensure the system cold fill pressure is correct, there are no water leaks and the
system is correctly vented of all air.
Replacing the pressure relief valve
• Isolate the boiler using the appliance isolation valves on the flow and return connections to the boiler.
• Disconnect the pressure gauge tapping from the top of the relief valve.
• Release the discharge pipe from the valve.
• Remove the pressure relief valve from the pipe work.
• Refit a replacement pressure relief valve in reverse order using a recognised method of sealing the
threaded joint.
• Open the isolation valves, ensure the system cold fill pressure is correct, there are no water leaks and the
system is correctly vented of all air.
Replacing the pressure gauge
• Isolate the boiler using the appliance isolation valves on the flow and return connections to the boiler.
• Remove the pressure gauge from the pipe work as described above.
• Depress the locating tabs on the gauge body and push the body through the mounting bracket.
• Refit a replacement pressure gauge in reverse order ensuring the seal at the pressure relief valve is
sound.
• Open the isolation valves, ensure the system cold fill pressure is correct, there are no water leaks and the
system is correctly vented of all air.
8. Fault Diagnosis
If a fault develops, or is suspected, call your Service Engineer as soon as possible
Go through the following checklist before you make contact
• Is the electricity supply on?
• Are the lamps lit?
• Has the limit thermostat tripped?
• Are the boiler isolation valves open?
• Are the pump isolation valves open?
• Is the boiler switch on (giving a red “Power ON” light)?
• Is the heating system water pressure correct?
• Is the boiler temperature control set correctly?
• Is the time clock (if fitted) calling for central heating?
• Is the room thermostat (if fitted) set high enough?
• Are the radiator valves open?