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# How critical is the distance between the Main Steam to the water line

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Member Posts: 67
I have measured the Single Gravity Main Steam pipe to the Normal Water line and I have 43". Is this ok?
I see from Dan book "If you have a gravity-return system the lowest, horizontal, steam-carrying pipe has to be a minimum distance above the boiler. In one-pipe steam, that distance is 28 inches.
thanks
Dan

• Member Posts: 8,578
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What height is the end of the dry return from the water line. I think this is the "lowest steam pipe" in the system. When the boiler is firing at its maximum pressure of 1.5 psi, the water level in the wet returns will rise 1.75 inches for every ounce of pressure. If the end of the dry return and its main vent is too low, then it will become submerged with this rising water level, and cause banging, and inoperative main vents.
The solution would be to raise the dry return, or lower the maximum pressure (which is why we like Vaporstats here). You only need a couple of ounces of pressure to get the steam throughout the system.--NBC
• Member Posts: 23,428
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Too low would be a problem. Too high is no problem at all.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 67
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Nicholas

The measurement from the ceiling to the main steam pipe is 10"
and the boiler water line is 53" from the ceiling so the difference is 43". I am going to use a Vaporstat control. I feel relief that this is ok. Thank you for the help.

Jamie

Thank you for the help.

• Member, Moderator, Administrator Posts: 16,544
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That's fine, Jamie. Make sure you have good venting if you're using a vaporstat.
Retired and loving it.
• Member Posts: 67
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Just calculated the venting using JP Freeley spreadsheet. Using Groton valves.

thanks
Dan Leary

sorry I was thanking Jamie and Nicholas for their help. Also thanks for the input.