main steam vent

Jim_42

I have a single pipe steam system which as far as i can tell does not have a main air vent. pipe comes off the boiler to a header and off the header are lines leading to the 6 radiators.( single story home) At the end of the header pipe reduces in size down to the condensate return back to the boiler. I think i need a main air valve but am not quite sure where to locate.any suggestions.Boiler seems to short cycle which i believe is caused by lack of venting and therefore pressure acting at the pressurtrol.

STEVEN MARKS

Install the vent downstream of the last radiator. The purpose of a main steam vent is to vent the main first so that steam can rise to each radiator evenly. Installing radiator vents will help balance the system.

Steamhead

And

measure the length and diameter of your mains, so we can tell you what vent to install. All vents are not created equal!

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Jim_42

The main is 2" and 45 ft long with 1 1/2" lines to rads

Steamhead

Use a Gorton #2 main vent

the biggest one made. If there is no vent connection, one could drill and tap a 1/2" pipe-thread hole in the side of the last radiator takeoff tee, and elbow up to the vent. Unless you're experienced in this kind of work, it's best left to a pro.

If you can't find Gortons in your area, Gorton's web site with contact info is www.gorton-valves.com . Talk to Ken Kunz and tell him I sent you. They will sell direct if no one near you handles their gear.

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scott75

I actually have this same situation. I have a vent however on every rad. Does this mean I do not need a main vent? Sounds like a lot of work to put one on. Also, last season when I filled and fired up my boiler, the rad vents popped off alot until all the air was removed. This season not one air vent popped off, but the entire rad still got hot, so I assumed there wasn't a problem.

dean_8

vents

Your situation was like mine until last Feb. when I reinstalled the main vents that had gone missing over the years. Your radiator vents are doing all the work. You need main vents also they get rid of the air in the mains so all the radiator vents have to do is vent the radiators themselves. These are things I learned from Dan's books; We Got Steam Heat and The Lost Art Of Steam Heating which I bought and read and are highly recommended

scott75

Thanks Dean. I started in this field 6 months ago but my company does mainly forced air, not much hydronics. I plan on getting those books in the future but for now am reading others. So the worst thing is that I lose a little efficiency? Once the air is out is stays out though, right? I don't know how air would be introduced to the system unless I drained it down and opened it up.

Unknown

Same page?

Are you both talking about steam systems, or is one of these hot water??

Noel

Steamhead

Not just a little efficiency

if the main now takes 7 minutes to fill to the end with steam, and you can reduce that time to 1 minute with the right main vent, the radiators on the end of the main will get steam in 1/7 the time they formerly waited. That's a big difference!

Every time a steam system shuts down and cools, the radiator vents open and air gets back in. This is normal, but it means the air has to get back out on the next cycle.

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scott75

We're talking about steam (at least I am). What gave the impression one of us was talking about hot water?

Unknown

Because

Steam systems only have water in the lower part of them.

They fill with air every single time they shut down.

No draining needed.

Noel

scott75

I didn't realize they re-filled with air everytime it shut down. That is a HUGE difference. I just thought that once the air was out, it was out for good. Thought maybe the lines would then be in a vacuum or something, wasn't sure. I though the rad valves were one way, so how does air get back into system everytime? Now for selection and location of vent? I would think the closer to the boiler the better. Then the air gets out faster, no? I would go on the horizontal main? I dont understand what is meant by downstream of the last rad. Does this just mean down stream of the last rad on the main? In other words, between the last two rads? I may need to have a pro look at this one.

scott75

Uuurrgg! Closest pro listed here is 84 miles away. Looks like I have to screen a local guy.

Unknown

for your pleasure...

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