sight glass issue

rayians · April 1

Hello all,

I recently acquired a home with an oil fired steam heat boiler/furnace. The boiler has a sight glass on it. I have never had to deal with one of those before.

To make a long story short, the house is vacant so I shut the furnace off to save some heating oil. I walked past it a few days later and noticed I could not see the water level in the sight glass. I was assuming it was empty. I ran water into it for a good minute or so and to my eye, the level didn't change. I checked it the next day, and the top of the sight glass was leaking. Apparently, shutting the furnace down raised the level in the sight glass and did not lower it. Therefore it most likely didn't need water, now I've apparently severely overfilled it.

A few questions on this, first of all, if I tried to turn the furnace back on, would I cause any damage or create a dangerous situation? Also, how can I drain some of the water out? How do I know what a proper level is if the level changes when the boiler is dormant?

Any advice whatsoever would be tremendously appreciated. Thank you all in advance!

delcrossv · April 1

There will be a drain valve near the bottom or lower 3rd of the boiler. Usually lookls like a hose connection.

You can drain until you see the waterline in the middle of the glass. Thats the normal operating level.

Overfilling seldom causes safety issues. You should be fine to start the boiler after adjusting the water level.

Probably good to get someone to look over your system before next fall.

Lastly, get the book " We've got Steam Heat" available on this site. Very helpful for a new owner of a Steam system.

rayians · April 1

Would I be correct that the water level in the sight glass raised simply due to my shutting the boiler off and letting the system cool down overnight?

ethicalpaul · April 1

No.

delcrossv · April 1

Not usually. With the boiler cold, drain until the waterline is in the middle of the glass and then operate the system.

Keep an eye on what the level does and report back.

Do you have an automatic water feeder?

109A_5 · April 1

The water level should not rise excessively by its self. The water feed system automatic or manual may have a slow leak overfilling the boiler.

If you have an automatic feeder it should periodically raise the level to maintain a safe working water level, but not over filling it.

You really need to figure out if it was under or over filled. With the boiler off and cool, drain it than refill it so you know how the sight glass looks. Once at the proper level run it at least once to help push out the excessive oxygen to minimize corrosion.

EdTheHeaterMan · April 1

Since your water level is moving slowly in and out of the glass, there is most likely a blockage in the connection to the boiler. That is common on steam boilers, especially when there is no maintenance performed for some time. There are other locations that can get blocked or partially plugged including the piping that feeds the high limit pressure control (usually a Honeywell Pressure-trol), and the pipes that connect the pressure gauge to the boiler.

The book https://www.heatinghelp.com/store/detail/we-got-steam-heat-a-homeowners-guide-to-peaceful-coexistence/ is a must read instruction manual for the new homeowner that has never had a steam heating system before.

As far as turning off the electricity to the boiler is concerned, that does not add any water to the system and would not cause the water level to go up the gauge glass.

rayians · April 1

I did find the drain valve and was able to drain it down to the point that it is in the middle of the sight glass. I was still a little skeptical whether I should attempt to fire it up or not, but apparently that would be advisable at this point. I do not have an automatic feeder, it is a manual ball valve. I do have a low water cutoff so I am assuming there isn't much to worry about at this point. I will report back once I fire it back up.

ethicalpaul · April 1

See if over time the water level goes up, indicating the manual ball valve is leaking by. But I would bet that someone just overfilled it at some point.

Yes you can fire it up.

For what it's worth, i don't like automatic feeders. You can definitely be fine without one.

mattmia2 · April 1

Does the boiler also make domestic hot water?

rayians · April 1

I only ran it for 10 minutes just to see if I would have some sort of obvious problem. No issues at all to this point. I'll be curious to see if after a day or two the level creeps back up again. The boiler is also the hot water heater for the house.

mattmia2 · April 1

If the tankless coil or coil in the indirect, whichever it uses for DHW, is leaking, that will add water to the boiler.

ethicalpaul · April 1

https://forum.heatinghelp.com/discussion/comment/1850659#Comment_1850659

Good to know!

The More You Know Nbc GIF by For(bes) The Culture.gif

rayians · April 2

As luck would have it, I took a look at it today and the sight glass was full again. Apparently I have some sort of a leak. I shut off the ball valves for the hot water to see if that changes anything.

Intplm. · April 2

https://forum.heatinghelp.com/discussion/comment/1850806#Comment_1850806

1-Manual valve is leaking by

2-Auto-feeder is leaking by

3-Domestic hot water coil is leaking into the boiler.

I'll bet its number three, and hopefully not a combination of the three. 🙄

rayians · April 2

There is no auto feeder. My untrained guess is #3 as well. Since I've shut off the ball valves into and out of the coil, If the level does not rise tomorrow, would my guess be correct that the coil is the likely culprit? How else can I be sure?

delcrossv · April 2

https://forum.heatinghelp.com/discussion/comment/1850810#Comment_1850810

That would be pretty definitive.

mattmia2 · April 2

Note that there should be a relief valve on the DHW coil, especially if there is a valve on the outlet. In fact I would leave the valve on the outlet open and leave a hot water tap open somewhere or at least let some air in to the dhw system or you might have a leak in the coil that wasn't there before once the water in it heats with it valved off.

EBEBRATT-Ed · April 2

Close the cold water inlet to the coil and leave the hot water valve open to the coil. If you don't have a pressure relief valve on the coil you will have a hole in the coil if you run the boiler with both valves closed

rayians · April 3

I currently have the boiler off, even for hot water. I also have the ball valves to the inlet and outlet of the hot water coil shut off. There is also a manual ball valve to fill the boiler/sight glass.

I checked it today and yet again, the level was high. Is this likely a leaky ball valve? How can I possibly diagnose which of the 3 is doing it without process of elimination?

On a side note, the sight glass was leaking and when I attempted to tighten it, I heard a CRUNCH. Today I changed it. It went pretty smoothly, except when I opened the valves to the sight glass back up, it filled with completely rusty water. Usually maybe the bottom third is rusty and the rest is clear. Not the case today. I am wondering if somehow these clues tie together?

delcrossv · April 3

Rusty water is a different issue.

mattmia2 · April 3

turn off the cold feed to the dhw, leave the hot water side valve open and leave a faucet open somewhere. That will keep no pressure on the tankless coil. If it still rises it is the manual feed valve that isn't holding. It is likely you can hear it if it is leaking that much too. If there is a union above the water line but after the valve you can open that and see if water is running out there as another test.

EBEBRATT-Ed · April 3

@rayians

The reason you shouldn't shut both the hot and cold water off to the coil is I don't know if you have a pressure relief valve on the coil.

If you shut off both valves and the coil is full of water the water will get heated when the boiler runs and expand and possibly wreck the coil.

sight glass issue

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