You will need to locate the filling loop for your heating system. There will be either 1 valve or 2 valves. If you have just 1 valve this will be used to fill the system. If you have 2 valves, you will need to open both to fill the system. In this scenario it is recommended to open one of them to 45 degrees, then use the other to control the flow of water into the system. Your target fill pressure should be around 1.1 bar, or in the range between 1 and 1.5 bar.
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