Main Venting

Steamhead

Yes. That should work fine.

gfrbrookline

I did as Steamhead suggested with the piping and had the first bang free night in 17 years. My contractor told me there was about 2 gallons of water in the pipe. My system is so quiet now I find myself touching the radiators to make sure the heat is actually coming on.

One thing I will add is when my contractor saw the Big Mouths he asked me why I put steam traps where I should have vents. I think when he could actually feel the air moving out of them he became a convert.

Thanks for your help.

gfrbrookline

If I have a big mouth on each main, which I am told vent at 2cfm at 16oz of pressure and the mains were calculated at 1.5-1.7 cubic feet is there any benefit in adding additional venting? I am running at 14oz cut out.

MilanD

You'll gain some 30 seconds in venting speed..

Sailah

At 16 oz they vent a lot more than that. 3.6CFM at 3 ozs.

Fred

By the time you hit 14 or 16 ounces of pressure you aren't venting through the bigmouth or any other main vent. Vents close when steam hits them. They are there to vent the air out of the mains so that steam can easily move through the mains.

gfrbrookline

If I can get access to the ends of the mains would I be better off adding big mouths there as opposed to the end of the returns?

Fred

On a single pipe system, Anywhere after the last radiator run out is fine. You really don't need to vent air out of the dry return so at the end of the main is ideal, if you have a place to put them. Also, just to clarify a comment you made above, the Bigmouth will vent 3.6 CFM at 3 ounces of pressure. The vent will close as soon as steam hits them so, for the purposes of venting your mains, you max operating pressure is not pertinent, other than the fact that good main venting may reduce your operating pressure a bit.

gfrbrookline

Thanks for the clarification. I think you said adding another big mouth would give me a 30 sec gain, do you think it is worth it over the long range?

Fred

gfrbrookline said:

Thanks for the clarification. I think you said adding another big mouth would give me a 30 sec gain, do you think it is worth it over the long range?

I wouldn't spend the money for a 30 second improvement. Just not worth it.

gfrbrookline

Thats what I thought.

Luckily the owner of the basement unit is rewiring his place and will be taking some of the ceiling down so with any luck I can see what is going on with the mains. If I can I am assuming you would recommend moving the big mouths to the end of the mains?

Fred

gfrbrookline said:

Thats what I thought.

Luckily the owner of the basement unit is rewiring his place and will be taking some of the ceiling down so with any luck I can see what is going on with the mains. If I can I am assuming you would recommend moving the big mouths to the end of the mains?

It's not essential but it will probably give you better vent performance than you would get from adding another vent since you won't be venting the air out of the dry returns before the boiler starts pushing steam out into the radiators. If the ceiling is going to be closed up again, I would definitely leave the vents where they are though so you can see and service them when necessary.

gfrbrookline

That makes sense. I may just add a Gorton #2 to each since I have them and can reuse the piping from the old antlers with 2 G2's.

Fred

That'll work!