Digging back into one pipe air line systems

The Steam Whisperer

This is a subject that I have left for much too long because Chicago is loaded with one pipe steam systems. There is a lot of info. on the Paul type system, that requires the Paul vent, and these are outrageously priced.
However, I have come across one pipe air vent systems without paul vents. It seem to me that as long as you create a vacuum on those air lines, with maybe a condensor in the basement to deal with steam, you should be able to run the system. The system I have particularly in mind utilized what appeared to be a pot of mercury to provide air venting and then a vacuum seal with just plain air lines to the radiators.

Are the Paul vents really needed?

Steamhead

The Steam Whisperer said:

....... The system I have particularly in mind utilized what appeared to be a pot of mercury to provide air venting and then a vacuum seal with just plain air lines to the radiators........

Maybe an Eddy or Morgan air-line system? Both are in chapter 15 of Lost Art.

The Steam Whisperer

Thanks for giving me the names, I knew they were in TLA, but couldn't find them. It certainly looks like it would be possible to retrofit an air line system without Paul valves. When considering the cost of installing all new radiator vents and the even more expensive main vents, this could be a cost effective improvement to a system. I imagine the simple solution would be run a short piece of pipe or baseboard to cool any steam in the returns and help create more vacuum and the drain the moisture in the air lines directly back into the boiler. Run very low pressure so the water can get back into the boiler, especially since I would expect that the pressure in the air lines would be quite low, so you have more like a B-dimension to work with. Then vent the end of the condensor to a steam vent with a check valve... maybe with the check valve in a water loop like on a 2 pipe vacuum system.

I think I have some 1-story Chicago bungalows that I could do this on to see how it works.