No water in rads on 2nd floor

[STEVEN WARMUTH]

How do I get water in the radiators on 2nd floor

 

[Dana]

The system pressure when cold has to be sufficiently high to lift water to the top of highest elevation radiator. Unless you have unusually tall ceilings with the boiler in a sub-basement, the pressure at the bottom of the system (typically at the boiler, with a basement boiler room) a 2-story would be fine with the system set 12 psi. The weight of the water column delivers about 0.434 psi for every foot of elevation, so at 12psi at the boiler it would be able to lift water to about 27.6' above the boiler. If the top of the radiator is 30' above the boiler you'll have to raise the system pressure to 0.434 x 30= 13psi just to get the water up there, but ~15-16 psi to guarantee that it's always postively pressured when the pump is running.

With the system properly pressurized and NOT pumping, if there is an air-bleeder valve on the top radiators,opening up the valve allow the pressurized air to escape and be replaced by the incoming water. If your system has an "auto-fill" or "PRV" to keep adding water as the air escapes, great. If it's all manual, you'll have to overpressurize the system by 4-5psi for bleeding the air, then drain water to lower it to the desired operating pressure once the system is fully filled, no air.

If there are no air bleeders or vents on the second floor air purging gets messier, and requires mapping out the valves so that you can drain from some port on the system while filling the system in a way that requires the fill-water to flow through the second floor radiators. Sometimes that's simple & obvious, sometimes not.