2 pipe trane venting issue

Roma

After researching on the wall, posting, and speaking to a few experts via phone.  I added 2 gorton # 2 vents to the end of each of my mains.  I now have 2 hoffman 75's on each return as well.  The time for the heat to come up has improved.  It now takes about 11 minutes for the heat to hit the trane convector boxes.  Does this sound like a normal time?  I keep the thermostat set at 68 degrees and the cycles per hour are set at 1.  The system runs for another 5 mins or so before it satisfies the thermostat.  I actually shut the convector boxes in the room which has the thermostat so that it doesn't shut off (because it is satisfied) before the rest of the convector boxes (2nd floor) are good and hot.  I noticed that some of my returns in the basement are close to steam hot so I tested them with a thermal camera.  They appear to be bad.  I had them all changed about 8 years ago.  I have 21 boxes.  Should I change them all? 

Dave in QCA

find that bad ones

Roma, if it were me, I would focus my efforts on finding the bad traps and repairing them.  It sounds like the venting has improved the situation for you.  If you have a bad trap, that can cause all kinds of havoc in terms of not letting the steam go where it is supposed to.  You are fortunate to have a thermal camera.  I have had to simply go around and feel the return lines.  However, on my traps, I discovered that most of the time they were in the failed closed position, but sometimes, for some reason, the broken part would get moved to one side, and then the trap would leak by.  I have found it fairly easy to replace the bad elements.  I always keep a watch on ebay and buy them whenver they are cheap.  I have managed to collect quite a few "new" "Old stock" elements and caps for my old Dunham 1E traps.