Vapor System Radiator Sizing?

Harry_6

OK, all you extremely low-pressure guys. . . .Am I correct to assume that any vapor system that did not employ thermostatic traps on the radiators (Mouat, O-E, Broomell, etc.) used orifice valves and sized their radiators 20% larger to ensure complete condensation? When I see a system where someone has messed with valves and/or return fittings I always try to find a component that will tell me what kind of system it was so I understand if the radiators (and boiler) are sized as they appear or are larger because they will never heat completely. What say you? Always 20% larger if it has a special fitting and not a trap?

Jamie Hall

You could also say -- perhaps more accurately -- the orifice or valve was set at 80% of the radiator capacity. Among other things, that allowed for some variation in pressure.