Radiators and Gravity System

Rich J

Greetings,

I have a very old gravity hot water system. All seven radiators are on the first floor (Ranch Style house). The heater (Make is a "Royal") is located in the basement. There is an expansion tank located next to and above the heater between the floor joists with a relief vavle connected to the tank. There is no tank or piping going to or in the attic as I have seen on diagrams on this web site. There is a water supply pipe connected to one of the heating pipes in the basement.

My question is when I open the small bleed valve on the radiators with a key, I get a small amount of air but no water. Do I need to open the water suppy valve connected to the heating pipe in order to properly bleed the radiators?

Thank you.

Guy_6

pressure

You will want to have about 10 PSI in the boiler BEFORE you begin to bleed the radiators. When it drops out, go down and fill the boiler to 10 psi again.
If you were to leave the feed valve on (assuming that there is no reducing valve on the system), the incoming pressure would exceed what you could vent, and that makes for soggy feet. Set to 10ish, bleed, set again and so-on. When finished, leave the pressure at 10.