Steam Radiator Vents - how to make a choice?
I recently bought my first home, a 1940 Cape with single pipe steam heat. Two mains, each about 30' of 2" pipe. One main supplies 4 radiators on the first floor (two are double sized); Second main supplies 6 radiators including 2 on the second floor.
I understand the venting concepts. What I have a hard time understanding is how to quantify the capabilities of different valves...
Quantitatively speaking, for main vents, what is a Gorton #2 capable of accomplishing versus a Hoffman #75H? From what I have read I get the impression they sound comparable in application?
Also, for radiator vents... I'm even more confused as to how to shop for them? The tongue on the Hoffman 1A is a smart idea which I don't see on any other parts. I'm still confused quantitatively speaking as to what the capabilities are? I've read in forums where rules of thumb are noted ('use #x upstairs and #y downstairs)... but it doesn't seem that those numbers are industry standard? Why else would a #2 Gorton main vent be comparable to a Hoffman 75?
I am asking here because I grew up watching TOH on TV and explanations are always very thoughtful.
Re: Steam Radiator Vents - how to make a choice?
Just a follow-up to shorten/clarify my inquiry:
Is there a reference to the air volume capability (in CFM -or other metric) of both radiator and main vents?
In my mind the comparison quantifiers should be air volume capabilities, orientation, and thread sizes. I think air volume is one of the most important and I don't seem to notice it in product details. My local plumbing supply is no help, they stock very limited, generic, options
I like the concept of the steam system. The underlying physics are elegantly simple. The house has the most comfortable heat I have ever lived with, just have some slow radiators.