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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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Re: Bosch Greenstar 25Si loosing CH fluid.You were right

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Re: Bosch Greenstar 25Si loosing CH fluid.You were right about CH fluid leaking out of the external vent pipe, I fixed a container at the end of the pipe, I must be loosing about half pint a day.Now we know where the fluid is going, how can it be fixed?
Hi , it does this because the boilers expansion vessel is split or flat, In the boiler is a metal vessel with a balloon inside that takes up the expanded heated water. When it goes flat the water has nowhere to go ,rises to 3 bar and dumps out of the safety valve.Bring the pressure to zero by releasing. Water from a bleed valve or drain off. Then take boiler case off ,locate the expansion vessel. Normally red metal casing. On the vessel will be a cap like on a car tyre.take the cap off and pump it up using car tyre foot pump.Pump up to 1.5 bar.
If the safety still drips, then it may have got dirt on the spring washer and may not be sealing properly. Take off and clean or replace. Put heating on and check that the pressure gauge isn't rising to 3 bar. If it does replace the vessel.Please don't forget to rate your answer, thanks
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