one pipe steam heat

Rrothowski

Is there any way to find main vents without cutting holes and looking with a flash light in my finished sheet rocked basement? ceiling and walls are sheetrock. Are they supposed to be in a particular location? maybe in the corners of the house? House was built in 1926 all black pipe. I'm restoring it back to 1926, I want to replace the main vents, Is it possible the 8 radiators vents are sufficient to vent the system?

KC_Jones

They are at the end of the mains, roughly speaking. So if one wanted the best chance to cut holes in drywall and find them, I would say look at the radiator layout in the house and see if you can figure out how the mains are run, then guess which radiator is last on the line and that should approximate the end of main.

All that said, are your returns overhead, or wet returns at or below the floor? I only ask because if you have overhead returns that are close to ceiling height at the boiler, you could put the vents in that location.

EBEBRATT-Ed

If at the ends of the steam mains they are dripped to wet returns the vents are usually at the end of the mains near the drips. If you have no wet returns and they are dry returns the vents can be at the end of the steam mains or at the end of the dry returns at the boiler.

You can add the vents to the dry returns at the boiler if you have dry returns. If the vents are at the ends of the steam mains and they fail and spit water, you will know where to look when you get a spot on the ceiling.

Long Beach Ed

If you are restoring an old house, you'll find many uses for a small inspection camera. These generally fit through a one-inch hole bored through Sheetrok, cost $70 and would be very helpful to search for things inside walls. Look where you'd suspect the steam main to end and you may see the vent, if it exists.

Most steam heating systems are far from perfect in their design, but most work to some degree. You can install big (fast) vents on the furthest radiators from the boiler and vent the system that way. The tradeoff to not having dedicated main vents is a reduction in the specific control of those radiators. Maybe the system will work fine, maybe it will work less than optimally. Only you can judge as you live with the system.

While you're analyzing the system, take a hard look at the near-boiler piping. Its configuration determines your steam quality, which dictates the specific imperfections and compromises that the system can handle.

dabrakeman

Send a few photos of your boiler from a distance showing the near boiler piping. We could help you determine if there would be a good place to put the vents there. However, if you do have main vents at the ends of the mains you would want to know since as @EBEBRATT-Ed pointed out one if one of those failed or fails open then it could cause some problems.

Rrothowski

Thank you all for this precious information, I will take all of it into consideration. I have a wet return under the floor. Long Beach Ed the suggestion about the camera is brilliant and will be buying a camera. Dabrakeman I will be posting pictures, if I can figure how to do that, but for now I'm replacing shut off radiator valves, PS restoring system back to the way it was designed, with thermostatic air vents, replacement shut off valves, insulation, and I threw in a vaporstat with the hope of improving efficiency. Thanks Again to all.

EBEBRATT-Ed

@Rrothowski

If you find at any point your adding a lot of MU water the first suspect is the wet return especially if it has never been replaced.