bubbles in steam sight glass


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Old 11-14-11, 05:43 PM
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bubbles in steam sight glass

I have a gas fired steam boiler that I maintain myself on a regular basis. I will clean the burner tubes and pilot assembly. Blow off the low water cut off regularly (weekly). Add water to the correct level and start the boiler with no issues. The last time I did the servicing, bubbles started to form in the sight glass. I will let some water out and the bubbles stop. About every three days or so I will notice bubbles in the sight glass. I have not noticed a pattern when the bubble appear...(begining, middle or end of heating cycle). What might a cause of the sudden appearence of bubbles be from? The boiler is about 4 years old and have never had this problem before.
 
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Old 11-14-11, 06:32 PM
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If you are on public water, I wonder if the water utility has started adding some type of chemical to their treatment system. Certain chemicals, especially when heated, will cause the release of gases.
 
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Old 11-14-11, 08:27 PM
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Explain what you mean by bubbles. If you mean that you will get a clear space with water above and below then you have some pretty crappy water or partially plugged gauge glass passages. How often do you blow down the boiler and how much make-up does it use?
 
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Old 11-15-11, 02:16 PM
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bubbles like putting a straw in a glass of water and blow gently. The sight glass is clear. The boiler gets blown down weekly via the low water cutoff. I have only blown down thru the return once and that is when I last did the servicing and the bubbles started.
 
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Old 11-16-11, 07:08 PM
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How often, and how much water do you add to the boiler? Does the boiler have an automatic water feeder? How often do you do a BOTTOM blow through the boiler drain? Have you ever cleaned the upper and lower gauge glass connections internally?

A few pictures might help.
 
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Old 11-17-11, 04:51 PM
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I believ a more inportant question here is residential or commercial system.
If residential do not use the return blow-down. Add as little water as possible. Flush LWCO only until it runs clean. Too much fresh water is as stated by Furd too much oxygen and chemicals.
 
 

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