two straight forward questions

puff_puff_hiss

Hi,

I have most bugs worked out of my 1 pipe steam system.  I just have two questions to trouble shoot the final radiator which i just can't seem to get to work correctly.  I have tried slow venting and fast venting,  but either way, I still get a lot of water (6-12 oz) that pushes out of the vent prior to the vent shutting and the radiator warming up. 





I have already tried pitching rad a little, pitching rad ALOT, and lifting the entire rad in order to pull the supply pipe up higher into the room, effectively adding pitch to the horizontal leg that is under the floor that takes me over to the wall to meet the riser.





my latest hypothesis leads me to two questions:



1) can a supply valve go bad BUT still have the following characteristics.



1.a    Valve will prevent air/steam from passing when in the closed position.



1.b    Valve will allow air/steam to pass into radiator when in the open position



1.c.   when in the open position,  valve will allow air/steam to pass by the valve, but will not allow condensate to pass back through on its way back to the horizontal leg, and ultimately back to the radiator.





what happens that leads me to these questions is a hot supply pipe and hot supply valve,  and a cold connection and bottom of the radiator nearest the supply valve on the rad side for a very long time during the heating cycle when all other radiators are warmed up.  I am wondering if water can be pooling up there because it can not pass the supply vavle on its return trip to the boiler, so it stays there until enough pressure builds to push it across the bottom of my radiator, up to the vent and out the vent. 



 

Second question,  Can 12 oz of water be pushed up a 12 foot high vertical riser realistically speaking?  It 1.75 inch pipe and my simpy brain is having trouble understanding how that would happen.   If the answer to this is NO,  I know that my problem exists at or near the radiator and I am on or near the right track with question #1. 







Thanks so much to anyone offering their knowledge.