Replacing return lines on one pipe steam

archibald tuttle

Especially if the return is oversize, if the pitch is carefully handled, where would the water provide a pocket to bang. I'm imagining a long building with mains down the two long sides from what's been reported. Don't know what the distance between the two mains at the end is, but assuming that the new wet return would run down one long side and that what is envisioned is a dry non-trapped return of oversize diameter going from one side of the building to the other to tee into the drop to the wet return and I don't see where you would have a water trap for hammer.

Might still be more economical of materials to drop straight away to wet return and could use smaller cross and then tee, but sounds like there might be stuff in the way.

Chips

Replacing return lines

Both of my return lines need to be replaced. One zone is leaking and the other zone is leaking and clogged. (90 year old pipe) Both 3-1/2” returns run in the crawl that has limited or no access. Lines run to a condensate tank that pumps back to the boiler. The 4-1/2” mains run along the exterior walls attached to the ceiling of the first floor (3 story building) All of the radiators have been removed from the first floor of one zone and all but 2 radiators located at the very end of the main have been removed from the other.
Can I run new returns lines just below the mains sloped back to the condensate tank or boiler? Both runs are close to 100’.

Norm Harvey

Definately get a PRO for this job. This isnt something you should attempt unless your a very well educated steam professional.



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Unknown

New Steam Returns

Aside from getting a pro!!

You need to determine what type of steam system this is.

3 1/2" & 4 1/2" piping is odd in size.

3 1/2 may still be available but 4 1/2 is out.

Here are a few questions?

Are these wet or dry returns?

Is the system a two pipe air vent system, a One Pipe gravity vacuum sysem, a Two pipe gravity system or was it butchered over the years and is a little bit of all?

You need some one that knows these oldies but goodies. i spent many years working on these buggers and successfuly restored them to work as intended by the early designers and installers.

Sometimes when you fix something you will find problems that have been hiding in dark and those problems can become expensive to fix, so get some competent help.


Jake

Chips

Thanks to Dan's books and this place, I'm the closest thing to a pro in my area. Small town in south central Alaska.

Dave_4

just to clarify

4 1/2" is the diameter of the pipe not the circumference?

bob young

inside diameter

inside diameter or outside. close to fifty years in the business & i never ever heard of 4 1/2 " pipe ever.

Chips

The pipe size is the OD, I don't know if it is sch. 40 or 80.
I think it would be considered a dry return, all though it enters the boiler room below the boiler water line and runs through a steam trap just before the condensate tank. It's a one pipe gravity system.
Chips

bob young

alternative measure

you might be able to slide copper or T.P. inside the existing piping [providing they are straight runs with no branch connections ]

Steamhead (in transit)

\"runs through a steam trap just before the condensate tank\"

That's completely wrong. If this is a one-pipe system it originally returned its water by gravity. Some knucklehead didn't understand this so they tacked on a tank and pump, and a master trap to keep steam out of the tank. No wonder the lines leak- the water hammer must be ferocious. No piping material will stand up to chronic water hammer.

If the outside diameters are 4-1/2" and 3-1/2", the inside diameters are 4" and 3". Run your new pipes below the boiler's waterline and into a Hartford Loop, and get rid of the pump and master trap. You'll have a simpler, quieter system.

If you run the pipes like I said, steam will never enter them so copper becomes feasible. Some people find this controversial, but we've never had trouble with copper returns as long as no steam can enter them.

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Chips

Thanks Steamhead, that's the best news's I've had all week.I would love to get rid of all that stuff behind the boiler. Because of many obstacles I would need to run the first 40'of the return well above the waterline and then I can drop down below the waterline. Would I need to put a trap in at that point or additional venting? I guess I'm just extending he main 40' with 3" pipe.Thank again for the help.
Chips

Steamhead (in transit)

The first 40 feet should be fine

drop below the waterline at that point, tie both returns in below the waterline and rise into your Hartford Loop. That's all you need- no traps. Vent the mains at or near their ends- for sizing vents, measure the length and diameter of each steam main and we can tell you what you need.

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Brad White

I have come across 4-1/2\" pipe

once in a 1928 McKibben designed house here in MA which had gravity hot water.

My Pocket Rocket pipe gauge had it squarely between 4" and 5" IPS despite no official designation. There was 3-1/2" pipe too in abundance on that house.

I think end-plate welding is the only way to connect to it, provided it is in good shape.

bob young

IF THE MAIN IS 4 ' pipe , the return may be oversized at 3 "

Chips

That was fast, thanks. Both mains are 4" one is 115' long and the other is 145' I have 2 Gorton #1 vents at the end of each main. Would I have to transfer those vents to end of the new 40'X 3" extension or add new ones? At what point would it be safe? to switch to copper. Thanks Chips

Steamhead (in transit)

You need a LOT more venting than that!

Gorton makes an even bigger vent, the #2, which is the biggest available today. It equals about 3-1/2 Gorton #1 vents. Even so, the long main would need EIGHT Gorton #2 vents and the shorter one would need SIX. This would get the steam to the ends of the mains in a few minutes with no more than a few ounces pressure.

A typical venting installation of multiple Gorton #2 vents is shown in the attached pic. We had a welder install thread-o-lets on the main and piped out from there. All piping pitches back toward the main.

No vents are needed where the piping drops from the crawlspace into the basement to go below the waterline. Why fill that pipe with steam if it has no radiator takeoffs?

The pipe can switch to copper where it drops out of the crawlspace.

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Chips

Would it be feasible to combine the two returns into one return before dropping down below the waterline. The drop or drip line will be over 8' long and enter the boiler room pit over 40" below the waterline.
Chips

Steamhead (in transit)

Nope

you MUST drop them both below the waterline before they connect. Otherwise steam may travel along the connection between the two, causing banging.

That's why the Dead Men used wet returns so often.

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Brad White_9

Brian, Your \"Ifs\" take out the variables.

If the return is oversized and if the pitch is carefully handled, you are right, there is no place for condensate to collect. The realities of construction, settling and other "not thought ofs" contribute to the situation.

A flat even over-sized pipe with some condensate on the bottom (where it tends to collect to say the obvious!) can, when under force of high velocity steam (read, low pressure), be induced into waves which will concentrate and force a sheet of water into an incompressible bolus, a juvenile delinquent with whiskey, car keys and a ski mask, out for trouble.

Dropping straight into wet returns has been the default for that reason.

EdyLogicMstr.

The mains do run down the long side of the building and then turn and run towards the center. The end of the mains and drops are 7' apart. I plan on extending the longest main( because it is already a little lower) over 7' and then running them down the center of the building 40' and then drop to a new wet return. The ceiling is 12' so pitch is know problem.Chips

Steamhead (in transit)

As long as

the two returns drop below the waterline before joining, and are properly pitched before they drop, you should be OK.

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