Supply Main Vent Cold

JohnLaPlante

Hi all,



I think I've confirmed what I thought was wrong with my system all along.  After coming out of setback this morning, I watched my system for 30 minutes.  The piping all around the vent got warm (progressively less warm as the piping got closer to the vent), and the vent itself was cold.  The dry return main vent was hissing away, but nothing was coming out of the supply main vent.  (pic below just for refresher...supply main vent is the farther of the two shown). 



This tells all of you that my vent is broken, right?



Assuming it is...is this something that can be cleaned (lime away or vinegar as some have recommended), or should I head to pexsupply or my local plumbing supply store and purchase a new vent?



Thanks, all. 

Dave in QCA

This tells us 3 things

If I am following correctly, it is the vent on your steam main that stayed cold.  The piping got warm, probably because there is a radiator take off very close there, and also the hot condensation in the pipe is running down the drip leg. 



This tells us 3 things:

1.  The vent on your steam main is stuck closed.

2.  The vent on your return main is stuck open.

3. The pressure is running too high, thus allowing steam to enter the return piping.  (This is based on the fact that we already know that you have a mouat system,)



You should have much more venting on your steam main than a Hoffman 75.  Probably a Gorton #2, or 2 of them.  We don't know the size or lenght of your steam main.



The Hoffman 75 is just fine on your return main, you can clean it up and it will probably work.  If you are replacing it, a Gorton #1 or a Hoffman 75 would be fine. 

JohnLaPlante

Steam Piping

Dave, thanks!!



I measured my steam piping at lunch today...I have about 42 feet of what looks to be 4" piping (can't tell without stripping insulation), and 20 feet of what looks to be 3" piping.



I'm planning on replacing all of the vents.  Million dollar question for you Dave...do you think I can do this myself?  I'm fairly handy with most things around the house, know my way around tools, and have managed to fix all of our plumbing issues including adding faucets, drain lines, water lines, etc.  I have never worked with this kind of pipe, however, so I'm a little hesitant.



Thoughts?

Dave in QCA

If the measurements are correct....

Your 4" pipe would contain 3.78 cu ft, and your 3" pipe would contain 1.06 cu ft.  In order to vent that main out in 2 minutes, assuming 1 oz of pressure, you would need 2 Gorton #2 vents.  They vent at 1.33 cfm each, 1 oz pressure.

JohnLaPlante

Thanks, Dave!

Thanks...off to PEX Supply to put my order in!



Smart man for staying out of the "Can this guy break his system" question, though . 

BobC

Large vent

The gorton #2's are physically large so you will probably have to elbow off your exiting pipe and come out to where you can get more vertical height.Also the #2's have a1/2" male thread so you will need a reducer to go from the 3/4" pipe size.



Make sure that everything slopes back towards the return so the water can find it's way back to the boiler and that you don't accidentally create a trap.



Bob

JohnLaPlante

Bob, THANKS!

Perfect advice...I think I'm going to give Dave's "Limeaway" cleaning treatment to them first just to patch together a fix.  Then buy the Gortons and have a plumber put them in for me. 



Great advice on the sloping...thank you!!