Surging - different water levels eliminate surge, does that help diagnose?

Woven · March 1

After doing a lot of reading, posting my first q here. Hello!

Boiler is surging at start up when water is higher than 3 1/2" in the sight glass. When the water level is exactly at 3 1/2 inches there is minimal surge, and when it's lower there's no surge at all. Surge is only as water nears/reaches a boil - ie: it stops after that while boiler still firing, but again, only if water is above 3 1/2".

When the water level is lower and there's no surge it isn't just that it doesn't surge up into the pipes and is low enough not to make the bad boomy sounds that mega-surge does, I mean literally no surge. Just a happy gentle expansion of the water with some small movement. At the lower levels with no surge the water in the sight glass stays clear. When it's above that and there is surge, the sediment gets all stirred up.

Would the change in surge depending on water level give you any thoughts about the most likely culprit of the surge?

(I have some thoughts, and have looked into a few factors, but I don't want to throw them out there in advance of hearing more expert thoughts.)

ethicalpaul · March 1

Water level is definitely a factor, but water level won't cause surging by itself unless you are at the very top of the glass.

Your water quality is likely bad—either oil on the surface or tons of dirt/rust/dissolved solids

Woven · March 1

Thanks @ethicalpaul

I definitely agree/get that water level itself isn't the culprit. If I thought that, then I would have assumed that I had already solved the problem!

Am I understanding right that you're saying even with bad water quality the surge could not occur when water is at a lower level?

ethicalpaul · March 1

No, I'm saying that even with bad water as the actual cause, the water line can influence whether and how much surging occurs.

If you have marginally bad water, then higher water level can make surging happen. That's what I believe you are seeing right now in your boiler.

techforlife · March 1

Agree on the need for skimming. Depending on the boiler, if the water level is high into the section coil cavities, it could be intensely rolling and circulating and stirring up the contaminates. It just makes it more obvious that the issue is contaminated water.

mattmia2 · March 1

perhaps when the level is lower the water that erupts from the surface with the steam because of the poor water quality falls back in to the boiler but when it is higher it gets thrown in to the riser. also maybe it is priming rather than surging and when the water level is lower the foam collapses before it gets to the riser.

EBEBRATT-Ed · March 1

Higher water level put the water level closer to the steam outlet pipe(s). The velocity of the steam/water increases going up the supply pipe. The higher water level gets caught in the increased velocity.

This will be exacerbated especially if the near boiler piping isn't right or is undersized.

Woven · March 5

Great, thanks all. Obviously skim was the first thought, but after seeing the difference in surge behavior with water level, wondered if this indicated skimming would be a waste and the main issue was something else.

This was influenced by fact that the sight glass levels I’m talking about are less than 1/2 of total. But digging into boiler specs, the post skim ordinary operating water levels (as long as I’m right that measurement includes boiler legs) are actually a little below where I’m seeing surge issue.

(For the curious for other theories, I’d already drawn off some ‘clean’ water and tested for foam by boiling it - no foaming). Will see what happens!

ethicalpaul · March 5

How did you draw it off?

Woven · March 5

With the water drain valve.

ethicalpaul · March 5

I thought that might be what you meant. That doesn't help because the oils that cause surging are floating on the surface. That's why skimming exists, to float those out from the top.

Woven · March 5

Yup. What doing this verified was the core water behavior re foaming. Ie: to see if there was an issue underneath whatever oil may be at the top.

Interestingly, had NE Steamworks out mainly prompted by another concern and the two who came convinced us skim not necessary at all. So, that's one thing settled.

techforlife · March 8

Please inform us as to what solved your problem. Thanx.

Woven · March 15

What I've laid out already pretty much covered it - keeping the water level low. I can get more into specifics on the steps I took while diagnosing and modifying water levels if that's helpful to you. Nothing additional was suggested.

ethicalpaul · March 15

It is my opinion that if you have to lower your water level to prevent carryover, your water quality is bad enough to warrant skimming and/or replacement (which you get basically automatically get with skimming)

Surging - different water levels eliminate surge, does that help diagnose?

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