Pitch on Mains

Bob Schultz

I have a question. I have a 2 pipe boiler system with 3 main run branches coming off my boiler and looping around the basement. The question I have is this house was built in 1920 and it has settled and has an uneven floor. My question is the Mains and return loops are attatched to the basement ceiling (uneven upstairs floor) and I just want to make sure that they all have the correct pitch. I know the pipes coming off the main need to be pitched up toward the radiator but I have't even until now thought about the mains. The mains are held up by metal strapping with holes so adjustments could be done. Thanks for any tips, just want to make sure they are not pitched the wrong way or if they are supposed to be level are not.
Ted

Steamhead (in transit)

Is this

a 2-pipe steam, or 2-pipe hot-water system?

"Steamhead"

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Bob Schultz

2 pipe Steam

Its a 2 pipe steam, as you stated to me before its an OE vapor system, hence the OE water elbows.

Steamhead (in transit)

I remember now

The steam mains rise to near ceiling level at the boiler and pitch down from there, 1 inch in 20 feet is fine. Pitch should continue until the drip (vertical) line at the ends of the mains.

The dry returns may pitch the same as the steam mains, or may be higher at the far end and lower near the boiler. The drip connection is the low point, and the vents may be located here too. Again, 1 inch in 20 feet is fine.

If the system has wet returns, they do not need pitch to help the water flow, but they should be pitched for draining and flushing purposes.

Generally, if a steam main is off-pitch badly enough to trap water, it will bang. A dry return may or may not bang, but trapped water can keep air from venting so some rads won't heat. So if your O-E is heating all the rads and not banging, your pitch is probably OK.

If some rads take longer to heat than others, the problem is likely not enough vents on the steam mains rather than their pitch.

"Steamhead"

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Bob Schultz

You are reading my mind

Yes, some radiators take longer to heat up. I had some banging but fixed that based on the feed pipes to a radiators pitch. I have one main branch where the first radiator take off goes up stairs and the second one on the line is downstairs and a small radiator. The second one, the small one heats up real quickly but the first one is like the last one in the whole house to heat up. I have been ordering new vents since at the end of my 4 returns I have only single vents on them. Plus there are a few places toward the end of the mains that have places I can ad more vents. This site has turned me into a steam addict!! Once that one upstairs does heat up though it heats fine, maybe just the run takes time. I am sure it will do well once the real cold weather hits. On that small radiator I am thinking about replacing the OE water elbow with a thermo trap because it really seems to pass the hot steam through pretty easliy and maybe the steam is just following the path of least resistance. Anyway thanks for all your help steamhead!!

Bob Schultz

Take that back

The second radiator of that main line is the uptairs bathroom, not the first floor.
Ted

Steamhead (in transit)

The O-E return ell

has an adjustable internal air vent. On the fast rad the adjuster may be loose or missing. For the slow one, try cleaning out the vent hole in the return elbow. The vent hole doesn't show up well in the Lost Art illustration.

Here's a scan of the O-E ad in the 1925-26 ASHVE Guide. It should answer any questions you have about that lovely old elbow....

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Bob Schultz

the slow rad

The slow rad was actually added at a later time because it is a long skinny one vs the big fat ones and they put a therm trap on it vs the water elbow. I do have some extra OE elbows which I was thinking about putting on the slow rad. As I told you yesterday, or the day before, the elbows that I have removed and replaced were missing that "important" ball but I have orders 10 balls and will be putting them in the traps, maybe that will help. Because the fast rad doesn't have that ball. I did turn the rad down with the adjustment valve and it seems to have helped but it still hisses like its still trying to push a lot of steam through. Thanks again for all your help. I will most likely be doing more steam work this weekend.
Thanks for helping out an upstater!
Ted