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To increase the pressure open the boiler water feed valve slightly and watch the pressure gauge rise to 20 or 22 psig... if the valve is already open, locate the pressure regulating valve fit into the water supply line and look for a lever on it that you can lift to allow city water pressure to bypass its regulation mechanism.
To bleed the radiators open the air bleed valve near the top of each radiator until a bit of air squirts out, then close it, wait 5 minutes with the pump running then bleed again. Air tends to migrate in the system,
There are other air bleeds in the systems as well, look for them at all high points in the system, you can bleed the air from the boiler itself by lifting the pressure relief valve briefly (stand clear of its outlet to avoid scalding.)
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