vapor system won't build more than 2 oz.; okay?

steve_6

Steamhead, I thought main vents only went the ends of the "returns" on a vapor system??

E. Holtman

vapor system won't build more than 2 oz.

I'm back at 'the wall'. I am getting an old system back on its feet. Yesterday, thanks to the wall, I discovered it's a vapor system (2 pipe). Clearly, whoever put in the last boiler didn't know this. I replaced the pressuretrols with a good vaporstat and a 16 oz. steam gauge. Set the vaporstat to cut in at 4 oz. (80 feet to furthest rad) and cut out at 10 oz.
Tenants love it, running better than ever however I noticed that the gauge never gets above 2 oz. and turns off by the thermostat being satisfied.
Is this a problem or a symptom of a problem? Or do I let it go and thank the long dead steam fitters for their fine job?
(Incidently, there are no steam traps at the rads, just VECO water traps with an orifice.)
Question #2: In the basement there are about 5 main vents located some on mains and some on returns. The locations seem kind of haphazard and they look like retrofits (near unions). What is the best venting scheme for this system? Should I plug them? Should I replace the vents with Hoffman 67's (as suggested by a local shop)? Which is to say, do I need to be concerned about the system pulling a vaccuum after shutdown?
Thanks for any help. This continues to be a great learning experience!
Eli

Mark Walnicki

Nice job!

Best way to learn isn't it?

I wouldn't be concerned about the pressure if everything is heating well. Your cut-in/cut-out settings sound about right. Hopefully all the mains are well insulated?

Do not plug the main vents, and if you do change them, go with the biggest vents you can get your hands on. Steamhead would know off the top of his head, but I'm thinking something like a Gorton #2 main vent. What kinds of vents are on the system now? I'm guessing they work since the tenants are getting heat. Do any of them hiss or whistle while the system is operating? Vacuum could be a problem if *all* the vents were of the vacuum type, but that's fairly unlikely. Check the venting and change out as needed.

Steamhead

That's probably all the pressure you need

if all the rooms are heating up evenly, you don't need any more.

If the main receiver/regulator unit near the boiler is gone (see "The Lost Art of Steam Heating", chapter 15, for a photo) you need vents on the ends of the dry returns to discharge the air from the radiators. You also need vents near the ends of the steam mains so the mains will fill with steam quickly. To size vents for steam mains, measure the length and diameter of the mains and post the info here. We can tell you what you will need.

You might want to get Dan's "Dead Men's Steam School" video and workbook. This lets you listen to Dan telling all about how steam systems were designed and installed!



To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

[Deleted User]

steve i think that was

just when the systems were coal. i think.

Steamhead

It Depends

many Vapor systems used radiator traps to vent the mains into the dry returns. From there the air left the system thru the dry return vent. You see this a lot on Hoffman and Dunham systems, among others.

If the steam distribution is poor, adding main vents will help.



To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Fred Harwood

Vapor system

Sounds like you can lower the steam pressure cutout even more. Try a cut out of 6 oz. By design, vapor systems seldom need more than 8 oz. Also, for thoroughness you might check the EDR for the total of connectec radiators in the house against the boiler input to make sure that you're not underfired.

[Deleted User]

Careful w/

any vent selection. Sounds like the local guy is dyslexic. If he said 67, he probably meant 76. The 76 is a vacuum vent. Stay away from them. If & when the vents need changing, think Gorton #2 or Hoffman 75. We have gone #2 or double #1s on everything. sounds like the system is humming along. Amazing ain't it?

E. Holtman

what's the difference between 76 and 67

> any vent selection. Sounds like the local guy is

> dyslexic. If he said 67, he probably meant 76.

> The 76 is a vacuum vent. Stay away from them.

> If & when the vents need changing, think Gorton

> #2 or Hoffman 75. We have gone #2 or double #1s

> on everything. sounds like the system is humming

> along. Amazing ain't it?

E. Holtman

What's the difference between 76 and 67

Why, 9, of course! The dyslexia was mine, he recommended 76's (I think the price was $67!). In any event, thanks for the warning. I can't understand why a vaccuum vent would be useful or appropriate.
The system is AMAZING. I will be adding up my EDR next week. Also, I've discovered quite a mix of rads with thermostatic traps and with the VECO water-trap/orifice things. I'm going to run a wire through all the orifices next week. How big a hole am I expecting? (so I bring some appropriate wire.)
Thanks to everyone discussing this topic. It's been very helpful to listen in. And the generous offer to suggest venting from Steamhead. As soon as I have enough info to describe the system, I will.

Mark Bagdon

Type of vent on dry return

Myu two pipe system circa 1935 has a large (2-3" dai x 5" high vent at the end of the dry return (furthers from the boiler). I can't see it well due to new celler walls put up in that room (wood panelling - yuk). Seems to work fine, but it kind of gurgles and farts when the system he heating up. The radiator traps and return trap are Trane. Is this just a large old air vent. Will it last forever. How will I know if it goes bad?

Thanks for any help.

Mark

Steamhead

It's probably an old Trane float vent

which was built like a tank! But even these eventually wear out. A Gorton #2 would be a good replacement.

www.gorton-valves.com

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"