Proper Main Vent size

Aveeight

Just got my Steam books but I haven't gotten that far into them so here is another questions for everyone.



I was wondering if anyone could give me a rough estimate of the size/quantity my main vent should be. I have about 85ft of pipe in the basement serving 3 first floor and 4 2nd floor radiators. There is only one vent right now (see attached). I am going to have it replaced because I think it is stuck open (its also stuck in the pipe) - I was wondering if when they go at it if its worth it to increase the number/size/type.

World Plumber

Balancing steam systems

If you click on the Shop link above; Books; then Balancing Steam Systems Using a Vent Capacity Chart. It's an e-booklet for down loading $10.00 about a ten minute read then you get into the charts.

    Best take a look and find what is causing so much water to get into the vents! They don't last long with water getting into them. 

BobC

Vent

If that 85 ft of pipe is 2" Id then you have about 1.85 cu ft of air in it plus whatever is in the header and boiler. That existing vent looks like a Hoffman #75 which is rated at 0.75 cu ft at 2oz of pressure. You need at least twice that so you might want to think about a Gorton #2 that is rated at 1.75 cu ft at 2oz. Two Hoffman 75's would work but that would cost more $$.



Bob

Rod

Venting

Hi- I was also wondering about the present vent and water. Could you take another picture of the vent but take it back farther so we can see the vent and the piping to which it is connected.

 You might also want to take a look at Gerry Gill's website. He's a very experienced steam pro in the Cleveland area

http://www.gwgillplumbingandheating.com/

. He co-authored the Balancing Book that World Plumber mentioned and has a lot of interesting material about steam heating on his website.

- Rod

Aveeight

Vent Pics

Here are 2 more pics of the main vent. I have a guy coming this week to do a service on the boiler, hopefully replace the boiler drain, and look at these. I would like to have him replace this vent with either 1 or 2 Gorton #2s on a tee if there is enough room. Would that be worth doing?

Aveeight

What water?

Why do you bring up water in the vent? We've only been here for a few months but I haven't noticed any water coming out of that vent - too much steam because I think it is stuck open - but not spitting water. Or is there a clear sign of recent water (damage)?

Rod

Vent Mounting

Hi- As you vent is placed at the very end of the pipe water rushing up the main is going to hit the end quite hard and continue up into the vent. From the green color on the vent  this is what has happened before. I've drawn on one of your pictures to show a possible  modification to the vent mounting.. Coming off the old vent pipe with a 90 elbow to which is attached a 90 degree street elbow, The 90 degree elbow /90 street elbow combination  gives you slope and direction.  yoiu then continue with a nipple and then to another 90 degree elbow /90 street elbow combination  and then to the vertical with a union attached to the top.  The union allows you to make up the rest of the unit (nipple,tee, plug,,street elbow and vent) on a bench and then attach it rather than attach everything in the air. The union also allows you to take the vent down easy for servicing or adding an addition vent to the tee. Air will travel easily through.the elbows but they will slow down any water. As for vents I'd start with a Gorton # 2.

- Rod

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