Pics to share....

Timco

Here's the returns. Hammering is both horizontal runs about 5' back from their tie together point.

Timco

Fred

No picture, but as long as they tie together above the boiler's water line, hammer is going to continue.

ChrisJ

Foam rubber insulation? That seems like a bad idea.


If those returns are hammering, there's water in them for some reason. They either need to be 98% dry, or 100% wet. Nothing in between.

Fred

@Chris, yea, he already said he's got two or three returns that tie together above the boiler's water line. The boiler is in a pit. He needs to take those returns apart and drop them into the pit, below the water line and then tie them back together. Looks like he has room down there to do that.

Abracadabra

could just disconnect one (the lower one) and bring that one down separately into the return manifold in the pit. That would minimize the work.

Fred

Abracadabra said:

could just disconnect one (the lower one) and bring that one down separately into the return manifold in the pit. That would minimize the work.

I think he said in an earlier post that there are 3 returns tied together. If so, as long as he gets each below the water line before tying them together or tying them into the the collection box, just taking one or two off from above and dropping them works.

Timco

So below water line would work even if that return has no water line and drains straight into the tank? I can make a trap.

Fred

If that return is below the boiler water line, it will have water in it, up to the boiler water line.

GW

if that wrench is 60", how tall are you????????????

Timco

The only connection from boiler to tank is a 3/4 pump discharge with a check in it.

Fred

I'd be inclined to drop those returns, as I originally suggested, to the floor of the pit, tie them together and bring the single pipe up to the collection tapping. That way you will know those returns are always filled with condensate .

Timco

Ah, now I'm getting you. Maybe a tee and BV to flush that too.

Fred

Timco said:

Ah, now I'm getting you. Maybe a tee and BV to flush that too.

Exactly.

MilanD

Make a p trap tall enough to overcome op pressure. Tie it in reverse of how it's tied in now. False wet return from there up to pipe drop up that run. Your banging is at the level of that 3rd return elbow before it drops down and ties in with the other 2.

Fred

@MilanD All of his returns are tied together above the boiler. The boiler is in a pit, below the floor. He has three, the two that come in from the right side and the one that drops straight down. The pipe that drops straight down goes to the pit.

Timco

Correct. East side, middle, west side.

MilanD

> @Fred said:
> @MilanD All of his returns are tied together above the boiler. The boiler is in a pit, below the floor. He has three, the two that come in from the right side and the one that drops straight down. The pipe that drops straight down goes to the pit.

@Fred I get it.

Create a false water line where the 2 pipes connect to a third, by inverting the connection into a "U" and bringing it up to just under the 90 of that 3rd return. This would make a large wet return/p trap between the 2 horizontal runs and the top of the "U", and would keep the steam from backing up the 2 horizontal runs up to that 22 el where the banging is. Then, that same pipe drops down to the pit, as before. This would separate the steam from all of the returns meeting above the water line. Like the pic I drew, sort of - I'm drawing on my phone with my finger.

Less to pipe. Water would flood all the pipes from the top of the "U" back to 2 horizontals to wherever the hight of the "U" is on the opposite 2 pipes, creating a water plug/trap. The "U" height needs to be as tall to overcome the op pressure so the p trap doesn't get blown, 28" per 1 psi op pressure.

MilanD

Just install a pet cock/drain plug at the bottom for flushing the gunk that'll collect there, and perhaps another plug at the top, to fill with water prior to turning on the system. Essentially, this is a trap, like the one below the kitchen sink. Terminates just below the 90 of the third return that is now there connected vertically and goes to the pit.

EBEBRATT-Ed

Don't the returns tie together and go back to tie condensate tank? This has nothing to do with the boiler. A vented condensate tank means no steam allowed in the returns. I am assuming this is two pipe steam with steam traps (bad traps) or something in the system to keep steam out of the returns.

Has nothing to do with the boiler water line

Timco

Correct. Two pipe. I used a vac breaker on the tank but not a vent because I didn't want steam getting all the way to the tank. On other tanks I hear them suck through a vent on a tank when they pump. Bad traps all around.

Timco

They also reduce from 2" to 1.5" all the way around the room. Sounds like a lot of water in there. They slam when the middle or last rerun gets steam to its vent. Shakes the pipes.

Fred

Clearly the best solution is to repair/replace the bad traps. Having said that, @MilanD , even with a Water seal, I still believe all that condensate from the two other returns dumping into that vertical plus the condensate from that third return will just create hammer anyway as it all run out of the water seal and into the vertical on its way to the pit. I guess if he has time to test which approach works best, he could do that but we all know taking the two from the right loose, plugging the openings in the Tees and dropping those alongside the one that already goes to the pit will work. The pit is right there, in front of those returns. He has three perspectives now:
1. Fix all the traps (best approach if customer will spring for that)
2. Drop the two returns to the pit and tie it into the third at the floor of the pit, ensuring all three are full of water up to the water line.
3. Create a water seal and hope the steam + condensate from that vertical plus the condensate from the other two returns flowing out into that steam doesn't create any hammer and that the system pressure is low enough that it doesn't blow the water out of that seal to a level below either of those two returns.
That is the order of the approach I'd take but it's not my job and I'm not dealing with this customer.

Timco

They won't do traps. I have a green light to propose what will fix it without the cost and notices for all 32 units. I need a finer gauge because I'm running at or below a pound. Gauge never moves and the building is fine.

Fred

You got the best suggestion I can offer. One other thing I see that you may need to address. In your second picture (of this last group), looking down those returns from the right. That top return looks pretty level from the point where it turns that corner. It would help a lot if it had a bit more pitch towards this end.

Timco

What about full size 2" all the way? Why reduce?

Fred

2"s fine but I doubt the reduction on those returns is a problem. What is it 1.25"? If so that should work fine.

Abracadabra

The returns should be sized to carry enough condensate for the EDR they are attached to.

Timco

Just sounds like a lot of water in them, especially when it hammers. Figured more space couldn't hurt and good pitch. Vents are new.

HVACNUT

Need an asymmetrical coupling rather than the bushing. Expensive but worth it. Not a whole lot of steam experience but is that kind of inverted trap riser gonna cause problems?

Timco

> @HVACNUT said:
> Need an asymmetrical coupling rather than the bushing. Expensive but worth it. Not a whole lot of steam experience but is that kind of inverted trap riser gonna cause problems?

24" rise then dropped header. Works great and silent. Could not heat better.

Timco

So I'm repiping these today / tomorrow.

Thoughts on theses traps? Lots of hammer out in the field.

Timco

Timco

So I repiped those returns. It's silent. I mean silent. There's some bangs for a second way down the crawl space but such is life.

Timco

Fred

That's great news! Might be a sag in one of those pipes down in that crawl space but it sounds like you made major improvements! Gonna take a few skims to get all the oils out from the new boiler/piping but you are about there.

Timco

I do have to keep the tank about 3/4 full. Any less and I guess there's enough room to push the trap water into the tank and allow hammer. I'm running about 10-12oz.