gravity return line

bigalbert

I have an 80 year old gravity "wet" return line embedded in concrete beneath the basement floor that I would like to replace at the same time I'm replacing my old steam boiler. Is there a sleeve insert that I can use in the old line instead of either digging the old one up or running an above surface return line all around my basement walls ( a very long trip in this case)?

Steamhead

That wet return

is probably in such bad shape you couldn't get a "sleeve insert" inside it. If the concrete floor is very old, it probably isn't that thick and could be broken up easily to bury the new line.

You'll hear some differing opinions on this, but I've had very good luck using copper on wet returns. This type of return does not carry any steam so there's no chance of the sweat joints breaking due to expansion.

If you have to run the line above the floor and go around any obstacles, it's much easier to do with copper than steel.

Whichever way you go, install a drain so the return can be drained out and flushed out.

If the steam mains do not have vents at or near their ends, this would be a good time to add tees at this location to install vents on. The system will heat faster and use less fuel with properly-sized main vents.



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ScottMP

steamhead

What about the ph level of the return water eating out the copper ??

Scott

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Unknown

pH

pH should be under ten and above 7. If it is outside that range, the water itself probably is the problem.

I've seen a system from 1959 that is still running, that is mixed iron and copper, even on the radiation. There are plenty of copper finned convectors on steam out there, as well as fan coils in big air handlers.

These surprised me on first sight, but they work and last.

I'm an iron pipe guy for as much as possible. It's hard to argue about this 50 year old copper on steam, though.

Noel

Tom_10

When I do wets

be it copper or black, I use sched.80 and put ball valves at opposite ends w/ tees and and drains. Especially if they are buried. Just ran 160' of schedual 80 2" black and hung it 2" off the ground with threaded rod and clevis hangers to avoid digging. I took the handles off the valves and either wire tie them to the valve or give them to the bldg super to hold on to. That way, I can FLUSH THEM OUT once a year or so, and nobody can shut them off. Works like a charm and peace of mind is an added bonus. Whens the last time you saw clean water in 20 year old wet returns? If they are really long runs I will add some tees and drains along the way for good measure. I am used to being accused of overkill in these instances by plumbers and other non believers but for a couple bucks extra I'll take the heat (and so will my customers)any day. I would change them out even at the expense of busting up the floor. Theres really no easy(labor wise) solution here. Just plan for the futurewhen you do it.

Steamhead

Never seen that happen

though I'm sure it's possible, and could happen to black pipe too.

I find that if the system is vented properly and we aren't throwing chemicals into the boiler, the pH should be OK. Of course, the water supplied in Baltimore is some of the best in the world, so its pH is not an issue. This might not be true in some other locales.

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