air venting recommendations followup

STEAM DOCTOR

what is the recommended venting for the following.

 there are two mains. one is 20'-25' long.i  don't know the pipe size but the outer circumference is aprox 8" (i would guess that it is a 2" or 2 1/4" pipe). this main takes a 45 turn then connects to a "T" on the top of the vertical leg that connects to the wet return. on the top of the "T" there is a 1/2" nipple aprox 12" high that has a brand new Hoffman 45 air vent(i replaced the old vent a few weeks ago and this what the supply house gave me). the second main is aprox 15' long and has a circumference of 6". i don't think that it is vented at all(the basement is finished so i cant really tell for sure). the second main has a dry return until the boiler room so i suppose that it would be possible to add a vent over there. the house is a small 3 bedroom. the boiler is running on low pressure. thanks

STEAM DOCTOR

correction

the second main has a circumference of 6 1/2"

Unknown

Vents

Hi- Check this post  thread.

http://www.heatinghelp.com/forum-thread/127402/Help-finding-professional-rochester-ny#p1175217



There a lot of good info on vents and a good source for Gorton vents in that thread.  In one of my posts on that thread I had included a table which gives circumferences of difference size pipes so you can tell what the size of your pipe actually is. (It's  is a lot handier than guessing and I'm a bad guesser!)  Sorry I can't send your the table attached  this post but it's on another computer at work.  You mentioned a Hoffman 45? I'm not familiar with that number Is it possibly a # 75 ?   The 75 is about 1/2 the venting capacity of a Gorton #2    I'd just install a Gorton # 2 on each main and that should work pretty well for you. se a tee and a couple of elows and pair the 75 and a Gorton# 2 on the large main. You can't have too much venting.

- Rod

STEAM DOCTOR

thanks for the chart

it was little hard to read(very small) still very useful. almost 100% sure that it is a 45 not 75. can check in the morning. thanks

Unknown

Chart

Click on the chart first to blow it up and then save it. That should give you a readable chart.