vent questions

danoer1

trying to figure out if this system is venting they way it should. I am running a 150,000 BTU Utica boliler in a 1 family old house (1700's up to 1900's) with two floors. There are 2 main vents (Dole Vents...#6B's). One of them gets hot to the touch and the other stays cool. I have taken them both off and soaked them in vinegar. How do I tell if they are venting correctly... if I cover them with a baggie should I see steam condensing? I have a mixed bag of vents on the radiators, with only one that seems to allow pressure to build up and then let's it loose, snaps shut and allows the pressure to build again. A bunch of them gurgle and hiss. The system is running at .5 cut in with a 1 psi differential. Thanks



dan

BobC

bad vents?

The main vents should release air until they sense the hot steam, at that point they should snap shut. I can't find any reference for a Dole 6b but if one is staying cold it has probably frozen shut. Boiling them in vinegar for a half hour will remove the crud that is sealing them shut about half the time.



The real question is what sized main valves should you have. Measure the length and diameter (or circumference of each main and we can calculate what volume of air you have to vent so the steam can fill the main. From that we can tell you what kind of main vent you should heve. Also do your main valves thread into a 1/4 - 1/2- 3/4 pipe thread? I've enclosed a handy chart that one of the guys posted that should make this easier.



Air valves will usually pass air until they feel the steam. They snap shut and stay shut until the steam condenses inside the pipe or radiator, that cools them down and the valve will open up and begin to suck air into them until more steam comes up the pipe to force the air out. If you hold a piece of tissue paper you should be able to see the air moving out of a valve, using your hand is tricky because when the steam gets there you'll get a steam burn if your not careful.



Each radiator should be vented according to it's size, large radiators are usually vented faster than small ones. Hoffman 1A's are adjustable between 0,026 and 0.225CFM, Ventrite #1's can be set from fully off up to 0.125CFM - with these you can dial in the correct settings without experimenting with fixed orifice vents, the pro's can just look at the system and select the right vent but that takes a lot of experience.



Bob

Steamhead

I think

the 6B was an older Dole vacuum vent. Time to replace them, since vacuum can hold water up in the pipes. Same with any vacuum radiator vents you might have.



Measure the length and diameter of your steam mains and we can tell you what's needed.

danoer1

Main Lengths & Diameter

Copper header at 2 1/4" running into threaded pipe at probably 2 1/2"... I insulated the threaded pipe a number of years ago. The header is uninsulated (correct?). One main is about 30 feet long, the other is about 41 feet long. Most of the risers go off at about 45 degrees and then vertically up. One riser is at a shallow pitch because it runs into a crawl space for a good 20 feet before it "rises" up to the "radiator" .

I'm going to give the boiling in vinegar a shot to see what improvements might come of it. Thanks!



dan