Return Line Routed Under Doorway. Is this a problem?

alexh

Hello all,
My fiancé and I have been learning a lot about the one pipe steam system in our house and are motivated to get it working as efficiently as possible. In our basement we noticed the water return line is routed under our pantry doorway. This is located about 30 feet from the boiler on the opposite side of the basement. Both sides of this "trap" get hot during heat cycling. Is this appropriate execution or should the routing be modified to help the system work better?

https://imgur.com/soqJIAW

Thank you for your help!
-Alex

Jamie Hall

This line is below the boiler water line for its length and just dips down and comes back up? That's no problem so far as water circulation is concerned. It may, in time, trap some sludge, though, slowing return flow. I'd leave it be at least for the time being.

alexh

Hey Jamie,
The entire portion is below the boiler water line. I'm sure it hasn't been cleaned in many years. Any suggestions on how to clean this thing out?

Jamie Hall

Unless the water is slow to return to the boiler, I wouldn't worry about it. Whether it is easy to clean out of not depends on how it was piped. If you have a nice convenient plugged T at both ends or unions which you can open up without breaking something... it's a hassle. The theory is you open up both ends and run water from a hose through it to flush it out -- but if you can't conveniently open up both ends you can't conveniently to it! If it ain't broke, don't fix it.

Lance

I run into this a lot in old homes. Many times, the pipe becomes clogged with sediment or closes up due to corrosion. Often there is never any means to properly flush or even test the flow of this elongated trap of pipe. We install valves and drains to isolate the section and flush. We remove and replace if clogged. If it leaks it can be a hidden loss of water and an early failure of a steam unit. Of course, under the floor means dig it up. Now to appraise it a pressure test should be made. But at what pressure? An open system may have as little as one pound or less. It may be clogged or half full of mud. It may not leak. It may leak after flush & pressure test. But if it does, it means it did not meet code and must be replaced. I pressure test to no more than 10 PSI even though a system has a 15 PSI relief valve. Flow under pressure is not always an indicator of function. A clogged pipe on extremely low flow can easily reclog and cause return problems. If the pipe is old and new is being built on top, now is the time to dig and replace and upgrade to allow test and flush for maintenance. Always flush before leak test.

retiredguy

I was taught that you never trap a return line by going under a doorway. In that screen shot, I would have gone "down and under" and also "up and over" the door to remove the U trap. Correct me if I am wrong.

Long Beach Ed

In certain systems where air must be carried with the water, good piping practice would dictate a 1" loop with steam vent above the doorway as well to carry air. The invert under the door in that case would be one pipe size larger than the return.

Jamie Hall

retiredguy said:

I was taught that you never trap a return line by going under a doorway. In that screen shot, I would have gone "down and under" and also "up and over" the door to remove the U trap. Correct me if I am wrong.

I've seen that as preferred practice, too -- but I've never quite managed to convince myself it's necessary in wet returns. As @Long Beach Ed said, if air has to be carried as well (a steam main or a dry return), then indeed one needs to do that (there are drawings of just that in TLAOSH) -- but in a perverse sort of sense a wet return is just one big, and uncommonly convoluted, trap all by itself. Hopefully it's full of water for its whole length.

Mad Dog_2

Whenever I spec out or run new wet returns I install gate valves, strategically placed tees with boiler drain cocks so that I can completely isolate the wet returns from the boiler all the way out to the drops at the end if the mains.  This enables easy full isolation and power flushing of the wet returns. The mud and sludge has NO Choice but to come out.  Mad 🐕 Dog

Long Beach Ed

I wouldn't bury them in concrete either. In a covered trough with plugs on the end tees.

EBEBRATT-Ed

I am with @Jamie Hall no need to vent over the top if it is below the boiler water line.

As the OP mentioned "both sides of the trap are hot" so it's not air bound its' working.


Think about an empty system and how it fills. The boiler water will fill the returns backwards and push the air toward the vents