Only bottom half of sight glass rusty

[Deleted User]

On a Crown Bermuda 103mbh steam boiler, only the bottom half of my sight glass water has dark brown solids floating and clinging to the glass. The upper half of the water in the glass is clear. But the boiler water itself is clear when I let some out from the bottom drain. When I remove the sight glass, there's dirty water in the lower sight glass valve when I open and drain it a little. The bottom-half sight glass rust returns every time I reassemble it. The ph of the water is 9.0 (by electronic meter, properly calibrated) with a Steamaster tablet having raised it. It was a new boiler last year and I skimmed a couple hours. Water bounces only 1/2" in the sight glass.

Is the upper half of the water in the sight glass clear because of residual oil, even though it's not bouncing? Is air getting into the bottom valve of the sight glass, causing local corrosion there? It's just a mystery why only the bottom one-half of the water in the glass turns dark.

KC_Jones

Post a picture so we can more clearly see what you are talking about.

icesailor

Did you ever boil water to cook pasta? And add olive oil to the boiling water? The olive oil floats on the top.

Have you ever noticed a bottle of Olive Oil & Vinegar salad dressing? The oil is on the top and the solids are on the bottom. Shake up the bottle and mix it up. Then let it sit for a time. The heavier solids sink first and the lighter solids sink last. But they all sink.

Seems to me that the solids in the bottom of the sight glass are like the solids in the bottom of a bottle of Newman's Own Olive Oil & Vinegar salad dressing.

nicholas bonham-carter

Have you taken the tube out to clean it with a skinny bottle brush? In my gauge glass the iron stain seems to be more pronounced at the bottom, but is easily cleaned.--NBC

[Deleted User]

Yes, I've cleaned the glass, on several occasions. The strange thing is the water drained from the bottom-most valve of the boiler is *clear*. If it were a need for more skimming, with the top half of the sight glass mysteriously filled with transparent oil, wouldn't it be bouncing more than 1/2" when the water's boiling? It's not dark enough to show in a photo yet, because I just cleaned the glass again. In a couple weeks though, that bottom half will be filled with dark solids all over again. Right now, the solids are just starting to cling to the bottom half of the glass. The dark ugly stuff from the lower sight glass valve slowly pushes its way up. In a few weeks, it will be almost black yet never higher than 3.5" of the 7" of sight glass water.

BobC

A nice slow skimming might get rid of those solids, does the boiler have a skim port available (1-1/4 to 1-1/2" diameter)?

Bob

nicholas bonham-carter

I have to clean my glass every two weeks, and the water seems very clear, but then the deposits return.--NBC

ChrisJ

nicholas bonham-carter said:

I have to clean my glass every two weeks, and the water seems very clear, but then the deposits return.--NBC

This is one of the reasons I insist on using water treatment.
I clean my gauge glass once a year and even that isn't necessary.

mitch, I recommend building a wand like this and pressure washing the boiler out via a skim port or any other large accessible connection.

Here is Gerry Gill's video of using a wand.
http://youtu.be/q1tw9rz-pUk

And here are pictures of the wand I built.

Fred

I don't think a skimming is going to fix this issue. The dirt or rust residue is on the bottom of the sight glass which, to me, indicates it's heavier than water and not oil. Being on the bottom, it isn't going to skim off of the top of the boiler water. It is probably just dirt and the boiler might benefit from a drain and flush after the heating season.

KC_Jones

What about adding a sight glass blowdown? I open mine up once a week and always get some cruddy water out of it. The OP says the boiler is new...perhaps it is some amount of crud working it's way back to the new boiler from the old system?

Charlie from wmass

Has anyone addressed the fact the rust is in the bottom half because there is no water in the top half? The rusty water is the water level in the boiler, there is no water above that point.

KC_Jones

Good point I guess I (maybe all of us) assumed they weren't saying the "air" is clear and the water is dirty. Perhaps the OP can clarify that?

Fred

Charlie from wmass said:

Has anyone addressed the fact the rust is in the bottom half because there is no water in the top half? The rusty water is the water level in the boiler, there is no water above that point.

The OP has a normal water level above the dirt level in the sight glass. but I do suspect the dirt line is where the water level drops to during a heating cycle.

[Deleted User]

There is 3 1/2" of clear water above the 3 1/2" of dirty water in the glass There are no symptoms of oil on the surface because there's no significant surging or bouncing in the sight glass. It's just odd that the solids only rise to a certain level in the glass and no higher.

ChrisJ

mitchg said:

There is 3 1/2" of clear water above the 3 1/2" of dirty water in the glass There are no symptoms of oil on the surface because there's no significant surging or bouncing in the sight glass. It's just odd that the solids only rise to a certain level in the glass and no higher.

Mitch can you take a quick picture of this?
It would help greatly.

BobC

A picture of the sight glass would help a lot.

There may not be oil on top of the water but there might be other crud - try the skimming and see if it affects the situation.

Bob

Fred

I'm going to take a wild shot in the dark here and bet the OP has a McDonald Miller LWCO with a blow down valve. I have seen this happen on my own system on occassion and I suspect it to be residue from the inside walls of the LWCO. What I have seen is not actually solids floating in the water, the water all the way up the glass is actually clear but the lower half of the sight glass gets a dark/ almost black haze on it that looks very much like the cast material used on the unfinished internal float chamber of the LWCO. Over the course of the heating season, after weekly blowdowns it gets better.
I did not see this when I used a water conditioner but I stopped using one as it was causing some foaming and I operate much better with plain water.

Abracadabra

The water drops 3.5" during a cycle. The movement of the water scrubs the glass clean.

Fred

Abracadabra said:

The water drops 3.5" during a cycle. The movement of the water scrubs the glass clean.

That's an interesting thought and may well be what is happening.

[Deleted User]

Abracadabra's idea makes sense, the scrubbing effect. The lwco is a Cyclegard though, with probe (wish it were a Safgard...). But why the dark crud appears only in sight glass and not in a blowdown from bottom of boiler remains a mystery. Maybe the dark crud is free-floating and would only drain out if I let the system completely cool down.

Abracadabra

mitchg said:

Abracadabra's idea makes sense, the scrubbing effect. The lwco is a Cyclegard though, with probe (wish it were a Safgard...). But why the dark crud appears only in sight glass and not in a blowdown from bottom of boiler remains a mystery. Maybe the dark crud is free-floating and would only drain out if I let the system completely cool down.

I haven't tested any of the crud I see on sight glasses but I'm guessing it's basically iron oxide that's flying around in the water and found the inside surface of the glass to attach to. After time more and more collects there. There's the same stuff in the boiler water, just not in the same concentration you see it attached to the inside of the glass. I'm usually able to clean off the inside of the glass by closing the bottom gage glass stopcock, opening the petcock or drain on the bottom with boiler under pressure. Steam cleans the inside of the glass. Just watch yourself if you try it so you don't get burned.

nicholas bonham-carter

I also have put a ball vave on the bottom of the lower gauge cock, and with many attempts at closing the lower valve, and opening the sight glass blowdown valve, while steaming, I have not found the results to be spectacular. The brush very quickly, and easily cleans the tube, so it's not a matter of rust being stuck on.
Of course, if I were operating at a pressure higher than 3 ounces, maybe I would have better luck.--NBC

Abracadabra

nicholas bonham-carter said:

...
Of course, if I were operating at a pressure higher than 3 ounces, maybe I would have better luck.--NBC

Heh... NBC, these are all larger commercial boilers that hit a max of about 1psi, so maybe the extra 13 oz. is what does it

nicholas bonham-carter

Mine is a peerless 211A-1,050,000 BTU, so I am commercial sized. But luckily low pressure.--NBC

[Deleted User]

Thanks to everyone, especially Fred and Abracadabra who pointed out the dirt line in the glass is likely the low point of a heating cycle. The system must be dirtier than I thought; will drain and flush next season.

Charlie from wmass

3.5" is a lot of drop for a heating cycle

ChrisJ

Charlie from wmass said:

3.5" is a lot of drop for a heating cycle

Agreed.

Abracadabra

A CrownBermuda 103MBH has 6.5gallons of water to the normal water line. I seem to remember someone on the forum having a problem with a small water capacity boiler and the manufacturer recommended height for the LWCO as the LWCO would always get tripped on every cycle. Anyone remember who that was? Based on the dimensions, the waterline appears to be about 15" from the bottom of the section. A 3" drop is about 20% of the water capacity. 20% of 6.5 gallons is 1.3 gallons. figure maybe .75 gallon backing up into returns depending where he's got his pressuretrol set? figure 400? gallons steam capacity in the mains /risers/radiators? That's about .25 gallons of water. Total of 1 gallon? plus a .3 gallon bounce on the water line?

[Deleted User]

Apologies! I exaggerated the amount of clear water vs. dark in the sight glass. It's really only about 1.4" of clear water above vs. around 3.6" of dark below. Very sorry for detouring this thread. I was basing it on a 9" glass when only around 5" is actually filled.

Fred

Nota problem, situation is still the same and I think what Abracadabra said about the scrubbing effect is probably the answer.