Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contactus/.
Click here to Find a Contractor in your area.
A & B Dimension
Options
RSGasGuy
Member Posts: 1
Having a discussion with a coworker, need a definitive statement about the location and application for the A & B dimension on 2 pipe LP steam. I have Dan's books  but they are buried in the basement. Thanks, Glen (Stay safe)
0
Comments

Assuming gravity return. "B" dimension is 30" for 1# steam pressure.
"A" dimension is 28" for 1 psi steam.
The difference is on one pipe you have steam pressure to help put condensate back in the boiler. On two pipe after the traps you do not have steam pressure to help push the condensate you only have gravity.
if you run higher pressure you have to increase these dimensions0 
>>On two pipe after the traps you do not have steam pressure to help push the condensate you only have gravity.<<
Folks who should know better often talk about higher pressure "blowing through trap". Cannot convince to lower pressure.0 
Thanks  appreciate the response.0

See attachment
Jake
P.S.
The dimension B is not often seen or understood by many service techs. We know tat you need pressure from some source to put the water back into the boiler. Example, if the boiler is is set to run at 5 psi we know that you need at least 6 psi in the return line to put the water back into boiler so in this case dimension B will be 5 times 2.3 equals 11.5 feet.
in many building there is not enough height for an 11.5 foot dimension B therefore a condensate pump will be needed to return the condensate to the boiler.
Steam: The Perfect Fluid for Heating and Some of the Problems
by Jacob (Jake) Myron0 
Has anyone ever seen an injector used to overcome too little B? If boiler is over sized then why not?dopey27177 said:See attachment
Jake
P.S.
The dimension B is not often seen or understood by many service techs. We know tat you need pressure from some source to put the water back into the boiler. Example, if the boiler is is set to run at 5 psi we know that you need at least 6 psi in the return line to put the water back into boiler so in this case dimension B will be 5 times 2.3 equals 11.5 feet.
in many building there is not enough height for an 11.5 foot dimension B therefore a condensate pump will be needed to return the condensate to the boiler.
0
Categories
 All Categories
 85.2K THE MAIN WALL
 3.1K AC, Heat Pumps & Refrigeration
 55 Biomass
 424 Carbon Monoxide Awareness
 73 Chimneys & Flues
 1.9K Domestic Hot Water
 5.2K Gas Heating
 130 Geothermal
 160 IndoorAir Quality
 3.3K Oil Heating
 61 Pipe Deterioration
 887 Plumbing
 5.9K Radiant Heating
 376 Solar
 14.7K Strictly Steam
 3.2K Thermostats and Controls
 59 Water Quality
 49 Industry Classes
 89 Job Opportunities
 28 Recall Announcements