Welcome! Here are some tips for using this forum.
System Balancing and Hofmann 1A versus Ventrite #1 vents
I live in a smaller 1928 house with a poorly balanced single pipe steam system which short cycles. Last year during the cold of winter I did my homework and read "Greening Steam" and skimmed "The Lost Art of Steam Heating." I dutifully measured my three steam mains, associated risers, and nine radiators and calculated the volume of air in each. I have the following questions/problems:
1.) Two of the three steam mains only service two radiators each and do not have main line vents, should they have main line vents? The third main services the remaining five radiators and splits into two branches about 20 feet from the boiler. The branch that services 3 of the 5 radiators on this line has the only mainline vent in the system located as recommended in Dan's books (at the end just back from the return). Should the other branch of this mainline that services two radiators also have a mainline vent?
2.) I have what appears to be a mainline vent, located right off the boiler. Is this necessary? What purpose does it serve?
3.) Hoffman 1As seem to have been the standard for adjustable radiator vents, however I have seen that their quality and ease of use may not be all they're cracked up to be...and that Ventrite #1s might be a higher quality alternative. However, I am aware of the slower venting rate of Venrite #1s versus Hoffman 1As, and so I am left wondering is there a general rule on how fast I should be evacuating the air out of the system to avoid back pressure and short cycling of the boiler?
4.) If I were to maintain the existing design of only having the above mentioned mainline vent on the long branch of my third steam main...is it feasible that I could adjust for this imbalance at the radiators with Hoffman 1As or Ventrite #1s?
Please let me know what additional information or photos you all might need to more accurately respond.