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Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
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water is pouring out through the overflow pipe at the back

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water is pouring out through the overflow pipe at the back of my gas boiler
Plumberpro :

Hi . this will be your safety valve . the cause is over pressurisation .the boiler has been over filled with water

Plumberpro :

As the water is heated the water expands and pushes out of the safety valve at 3 bar

Plumberpro :

Fill the boiler to 1.2 bar. If it rises to 3 then your expansion vessel has failed and may need replacing

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