main vent

turbobike

Is there any "rule-of-thumb" on replacing main vents?  I've been in  this house for over 30 yrs and never replaced it.  It's a Dole #5.  It shows evidence of water spouting out in the past, but not recently.

With the help of this website,  I've been slowly fine tuning the system .  The past summer I replaced all of the steam traps, and now all radiators heat evenly, all the way across. 

The system is a 2 pipe steam system , oil-fired. I have been unable to have the  system operate properly at the lowest pressuretrol setting.  At the lowest setting, the boiler will not provide the heat that the thermostat is calling for.  If I set pressuretrol at 3psi, it meets the demand and the house is comfortable.  Will replacing the old main vent resolve this, and allow a lower setting, or do some systems just require a higher setting? 

 

BobC

Dole is probably too small

Most systems work best when the main is vented very fast and the radiators relatively slowly. One sign of inadequate main venting is uneven heat. Working at a higher pressure will cost you more in fuel.



How long is the main steam main? the Dole #5 is not a large vent, you would probably be better off with a Gorton #1 or #2depending on the length and diameter of that main.



Bob

Dave in QCA

DOLE #5 is WAY TOO SMALL

It seems strange to me that Dole produced this vent, with a tiny venting rate, for use as a main vent.  Their 1A VariVents have a good capacity and work well.  The #5 however, is totally unsuitabe for use as a main vent and should be replaced.  It vents just a little faster than an old Hoffman #40 radiator vent.  If you compare it to a Gorton #2 main vent, it would take 17 Dole #5 vents to equal the capacity of the Gorton.  Even the Hoffman #75 is over 7 times faster than the Dole #5. 

Steve_175

Main dimenions

Tell us the diameter of your mains and how long they are. Posting a few pics of your boiler and the pipes connected to it would help too.

turbobike

main vent

sorry for the delay getting back to this....

I have approx 90 ft of 2 1/2 " mains. Last 2 photos are of a section where there is a branch off main steam line that goes into the return line. There appears to be a trap where it dumps into the return line. I really don't understand why this branch is here. Both this return line & the main line then drop to the floor into a mud leg, and then proceed back up the wall to feed more radiators

turbobike

main vent

sorry for the delay getting back to this....

I have approx 90 ft of 2 1/2 " mains. Last 2 photos are of a section where there is a branch off main steam line that goes into the return line. There appears to be a trap where it dumps into the return line. I really don't understand why this branch is here. Both this return line & the main line then drop to the floor into a mud leg, and then proceed back up the wall to feed more radiators

crash2009

Hoffman Differential System?

Is that a Hoffman Differential Loop hanging on the chimney?  Is that a dry return vented into the chimney?  If it is you just hit the steam lottery.

turbobike

main vent

yes-- to the differential loop

no-- to the dry return into the chimney

crash2009

I don't know much about how to make them work good

  But, I have read a lot of thread here, written by people who know how, and others that own and maintain them.  Everyone speaks very highly of them, and says they are very economical to run.  Yours must need a little nudge here and there for you to get the same results as others.  You may want to start a new thread with "Differential Vapor System" in the title.  I am sure this would attract some experts in this type of system.  Off the top of my head I think Jamie has one.

crash2009

Dave,

You made it back!  Last I heard, you were on your way to the Best house, fighting 4' snow drifts, on Feb 2.  Guess we both been busy.  Whats the best way to get this guys differential system working good? 

crash2009

bump

bump

Steamhead

If that Dole

was installed in the top of the Differential Loop, it's ridiculously small. The Hoffman #11 that would have been there originally was one of the fastest vents ever made. It had to be- it was the only vent in the system. A Gorton #2 is a good replacement.



The trap at the end of the steam main is called a "crossover". It's a standard radiator trap which vents the air from the steam main into the dry return, where it can flow back to the vent on the Loop. If this trap has failed closed, the main will vent slowly. If it fails open, it will pressurize the dry return and the steam might not flow at all.



These Hoffman systems were designed to run at 8 ounces, maximum. Yours can, too, with proper venting.