Changing dry to wet return

Klmdss

Is it possible or nonadvisable to lower a current dry return, which is about 3 to 6 inches aboves the waterline over of 20ft span into a wet return?  There are no real obstacles.  I can't get it all the way down to the floor, but can get it well below the water, probably close to the lwco trigger?  One pipe steam, no Hartford loop.

Jamie Hall

It's not only possible -- it's a very good idea, unless it is part of the venting (unlikely on a one pipe system). It's likely that in the original installation it was below the water line, and a new boiler was put in without paying any attention to the water line.

EBEBRATT-Ed

@Kimdss

The return needs to be either 28" above the center of the gauge glass (Or higher if a dry return)

If you turn it into a wet return it needs to be 2" below the gauge glass lower (bottom) connection)

Klmdss

Thanks, def can get below bottom of gauge, probably right around 2 inches. 

And that can be done (mostly) in copper, right?

JUGHNE

Where are the steam main air vents located at now?

Once return is wet no air or steam will pass, obviously.

Klmdss

air vent is located at the end of the steam main, right before it drops down to the return.

Jamie Hall

Should be good to go assuming the vent is adequate.

JUGHNE

IIWM, I would go with type L copper wet return.
You can go smaller than the "dry" return was.

Also I would add an isolation ball valve on each end, placed above the water line.
At each end then install a tee with ball valve with hose fitting/brass cap.
Then you can close the isolation valves and flush out the wet return with house pressure....hose on the water heater tank drain....flushes out that tank also.

Pictures?

Klmdss

I had to sell a kidney to buy all the copper and fittings and nearly gave myself a hernia twisting off the100 year old fittings, but everything seemed to go well enough. I realize too late I probably could have gotten away with 3/4 pipe instead of 1 inch. I did swap a couple 45s with 90s near the boiler to get around a sewer pipe. Figure wouldnt be much of an issue since its under the water line now.

I was going to add the shut off and the cleanout T as recommended but couldn't quite size it right with nipples and fittings available if I wanted to keep the copper all below the water line. It won't do any good until I replace the other return, and shouldn't be too much trouble to add them back in later if I can get a short piece of black iron pipe cut and threaded.