Steam Heat Main Vent - HVAC - DIY Chatroom Home Improvement Forum

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC


Thread Tools Display Modes
Old 02-27-2010, 11:50 PM   #1
Join Date: Feb 2010
Posts: 1
Rewards Points: 10

Steam Heat Main Vent

My (old) house has a one-pipe steam heating system. The main vent is at very the end of the steam supply main, on a tee in line with the vertical pipe that starts the wet return. Everything I've read says that the main vent should be about 15 to 18 inches before (that is, upstream of) the end of the steam supply main, not at the end.
Ques.1: How am I hurting by leaving the vent where it is; why is 15 to 18 inches better than zero inches? What is gained by relocating the vent?
Ques.2: How big a job is it to tap into the 2-inch supply main?
Thank you for your answers.


sizzz is offline   Reply With Quote
Old 02-28-2010, 04:59 AM   #2
paper hanger and painter
chrisn's Avatar
Join Date: Dec 2007
Location: Hagerstown MD
Posts: 7,679
Rewards Points: 30

I have found this site to be most helpful for my steam heating questions


chrisn is offline   Reply With Quote
Old 02-28-2010, 09:22 AM   #3
Licensed Master Plumber
Join Date: Dec 2009
Location: New Hampshire
Posts: 476
Rewards Points: 250

Change your point of view. The system was installed at least 50 years ago, probably a lot longer actually. The guy that installed it new what he was doing. ( it came with the terratory back then) Unless someone has messed with the system, leave it alone. If you think you are having delivery issues....

Bad radiator vents
Bad main vents
Clogged or partially clogged return piping
Wrong pressuretrol setting
Always ask to see your contractors license!
NHMaster is offline   Reply With Quote
Old 02-28-2010, 09:43 AM   #4
JohnH1's Avatar
Join Date: Jan 2009
Location: Chicago, IL.
Posts: 428
Rewards Points: 250

15 to 18" is because as the steam and water reach the end the water will basicly slam into the elbow. some water will go down and some up and into the vent causing vent damage. It will work at the end as it already has for years. But the proper location is before the end of the main.
JohnH1 is offline   Reply With Quote
Old 02-28-2010, 02:45 PM   #5
An old Tradesmen
Join Date: Oct 2008
Location: Somewhere
Posts: 32,961
Rewards Points: 7,288

As John said, proper is at around 18" before the end of the main.

As NH said. its been like that for a long long time. No reason to change it now. Unless your replacing teh main vent every year or 2.
beenthere is online now   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Repair or replace gas heat unit and power vent PegTN HVAC 1 11-06-2009 06:40 PM
steam heat problems alanliz HVAC 8 01-18-2009 08:10 AM
No Steam Vent for Dryer Bicycle Junkie Appliances 11 12-09-2007 03:58 PM
Flushing a Steam Heat Furnance helpless handyman HVAC 2 11-06-2006 04:34 PM
Steam heat vs Hot water heat helpless handyman HVAC 5 10-03-2006 08:57 PM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1