can I raise the wet return from floor?

Chris_108 · June 12

Hi guys,

Bit of a tricky situation and could use some advice….. Single pipe steam system with wet return that after dropping down to the floor hugs the perimeter of unfinished basement and runs back to boiler…..

I need to install a sump pump right in the corner where the wet return runs due to basement flooding badly in this area….

SO…. Can the wet return be raised10 or 12 inches off the floor? I know typically the wet return should be below the water line on the steam boiler so I am not sure what will happen if we raise the wet return up 12" or so so we can install the sump pump…

SO let me have it, am I crazy and going to screw up the boiler's condensate return or can I do this and if so what do I have to look out for?

Thank you in advance!!

Chris

Jamie Hall · June 12

So long as it stays below the water line of the boiler you will have no problems. I'd be really surprised if the boiler water line was that low, unless the boiler is in a pit.

Chris_108 · June 12

Hi Jamie, No boiler is not in a pit.. Can I start the horizontal run of the return slightly higher than boiler water line and pitch it down to the floor??

In other words now it drops from the ceiling height straight down to the floor can I drop it maybe 12-18" from floor and pitch gradually to the floor? It would maybe be above boiler water line for maybe a foot or two at most. Would this be ok?

EBEBRATT-Ed · June 12

It depends . Any return above the water line will have steam & condensate and that is a recipie for water hammer in a horizontal pipe.

If you keep it short like a foot or so it may be ok but it should be avoided if possible. Once you get below the water line you can go up, down or horizontal or any angle as long as you stay below the water line. And when we say below the water line I would strive to be 6" below minimum if you can

Jamie Hall · June 12

As @EBEBRATT-Ed says, it depends. There are ways to fudge the situation and create piping so that a pipe higher than the water line stays submerged — but these tend to get a bit complicate.

What you can't do is take piping which was intended to be below the water line and raise it so that it isn't any more without complicated plumbing. Not only are you likely to get water hammer, you may also inadvertently allow steam to go places it isn't wanted — to the detriment of your entire heating system.

I can't believe that your boiler water line is so low that you can't keep that return below it…

Chris_108 · June 12

I may be able to stay below water line but it will be close….

What is the science behind needing to stay below water line? In other words what causes things to get thrown off when return runs above water line?

thanks again guys!!

Chris

109A_5 · June 12

Sump pumps usually go into sump pump pits, which the top of the pit is flush with the floor and the rest of the pit is usually below the floor and also away from the wall at least a few inches to avoid the footer in some cases. I'm having a hard time understanding why the new sump pump would interfere with the wet return if it hugs the wall.

I'd reassess the sump pump install.

mattmia2 · June 12

I'd get it a few inches above the floor and use copper because it will not dissolve as fast as black iron in your wet basement. It doesn't need to slope, the water will still flow if it is flat. put boiler drains at the ends so you can hook a hose up and flush it out.

I would argue that a single vertical drip dropping in to a sloping return that is only part way below the water line on the slope will never see steam at the water as long as the pressure is controlled in the boiler because there is no way for the air to get out of the vertical pipe unless there is enough pressure differential to push the air through the water.

ethicalpaul · June 12

there is no possible pressure that can push air through a wet return in a 1 pipe system. The pressure is equal on both sides

otherwise I agree with Matt—what Chris describes will be fine. The return will go to water.

In fact, if you “think like steam” you’ll see that steam doesn’t ever go past the last runout (if there’s no main vent) or the main vent (typical scenario) to any significant degree

Jamie Hall · June 12

The level of mischief which a wet return which isn't we can cause depends on how many drips — verticals — go into it and what they drip from. And the system pressure.

If there is only one drip, not much harm can occur. However, if there are two or more, and one of them is from a steam line and the others from returns, the steam will happily get into the "wet" return and from there back up into the returns — and the system will heat poorly, if at all. Two or more steam drips may cause steam from one to get into the "wet" return and travel and get back into the steam main from the other. This can be a problem is there are no vents between the two drips, as air will be trapped in there and any radiators on that section will be slow — or not work at all.

And so on.

KC_Jones · June 12

Another option can be to raise it up much higher. Most of my returns are up high close to the joists. As long as they have a slight slope back to the boiler, it works fine. My entire wet return for both returns is about 2' long and only exists right at the boiler.

The boiler water line dictates everything. You don't want to be in the vicinity of the water line, well above or below is good, but running at that level has the possibility, in the right circumstances, of causing issues.

Jamie Hall · June 12

OK. Step back a square or two here.

We have a critical question which, I think, has not been clearly answered.

Do we have a wet return serving only drips from a steam main? Such as might be found on a one pipe system?

Do we have a "dre return" which is, in fact, a continuation of a steam main back to a boiler?

Or do we have a true dry return up there somewhere, which would be found on a two pipe system?

The rules for connecting them to each other, venting them, and the elevations they run at aren't made up old timers rules. They are basic physics, and getting it wrong is one of the more common reasons why systems don't work well.

Chris_108 · June 12

Hi Jamie, I have to investigate this a bit more, but I am pretty sure there is only one vertical drop from the end of the steam mains that goes from the steam main height vertically straight down the the basement floor and then runs along the floor all the way back into the boiler…

Jamie Hall · June 12

https://forum.heatinghelp.com/discussion/comment/1857815#Comment_1857815

If this is true, then the pipe in question is a wet return, and is serving as the end of main drip in a parallel flow steam main. A very common arrangement. And if that is true, then honestly you can run it at pretty much any elevation you like, so long as it keeps allowing the condensate to get back to the boiler…

mattmia2 · June 12

https://forum.heatinghelp.com/discussion/comment/1857825#Comment_1857825

As long as it eventually goes below the water line before it connects to anything else at the boiler.

can I raise the wet return from floor?

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