Steam boiler sight glass questions and answers, set #3.

This article series describes how to find & use the sight glass (or sight gauge) on a steam heating boiler to check or set steam boiler water level.

Steam Boiler Sight Glass Repair FAQs #3

These recently-posted questions & answers about the sight glass on steam boilers appeared originally at SIGHT GLASS, STEAM BOILER - be sure to review that article.

On 2019-02-10 by (mod) - what to do when boiler water drops out of the sight glass and LWCO does not turn off the boiler

Stafford,

What to do when the HydroGard LWCO does not shut off the boiler at low water condition

Watch out: Thank you for asking Stafford, as you've touched on a very important safety feature designed to avoid boiler damage, desctruction, or even more-dangerous conditions.

It appears that your CycleGard Low water cutoff LWCO is not working, perhaps needing sensor cleaning or, less likely, replacement of the control.

Periodic maintenance is needed to keep this LWCO working properly.

TO have space for a thorough reply to your question I have made a new page where I repeat your question and answer it.

Please see

LOW WATER CUTOFF VALVE NOT WORKING

and let me know how that works for you and do not hesitate to ask further questions or post other photos of what's going on with your boiler.

On 2019-02-10 by Stafford

My steam boiler doesn’t cut off when the water level falls to a point where I can not see it the light donesn’t come on on it a manual feed and a cycle guard low water cut off middle CG450

[see photo above provided by reader Stafford]

On 2019-02-06 16:17:18.683480 by ISAAC

When boiler fire the water in the sight glass drops all the way down one pipe system Weil McLean

On 2019-01-24 by (mod) - How to charge gauge glass in boiler?

Rakesh

To replace a steam boiler sight glass or boiler gauge glass

The boiler is shut down and cooled

Depending on the specific hardware (show us a photo)

it may be possible to close the top and bottom sight glass valves, then un -screw the glass mounting hardware, replace the glass tube with a new one of the proper height and diameter (and gaskets),

then re-open the vales and restore the boiler to operation.

If there are no working shut-off valves at both top and bottom of the sight glass then you'll need to shut down and cool off the boiler and drain its water level below the bottom sight glass fitting.

Be sure you have the right replacement sight glass for your boiler brand and model- sold by the manufacturer as well as by plumbing and heating suppliers, though a generic sight glass replacement will be fine if it is of the proper dimensions.

Detailed procedures and notes about steam boiler gauge glass or sight glass replacement are

at SIGHT GLASS REPLACEMENT

Also see details and photos at STEAM BOILER SIGHT GLASS REPLACEMENT FAQs

On 2019-01-24 by Rakesh

How to charge gauge glass in boiler?

On 2019-01-04 by (mod) - My boiler is new sight glass is a third full and the lower light comes on and the boiler will not start until I add a little water to it.

That sounds to me as if your automatic water feeder is not working or you have a problem with condensate return delay or both.

On 2019-01-03 by Clarence

My boiler is new sight glass is a third full and the lower light comes on and the boiler will not start until I add a little water to it. Then it run and heat the house. But the water will get third and the light come on and I have add more water.

On 2018-12-30 by (mod) -

No worries.

On 2018-12-30 00:17:37.531748 by Melynda

The Anonymous comment below is a continuation of the conversation I started earlier. Sorry I forgot to put my name in the form.

Thanks . I'll take some photos tomorrow and attach them. But some more info: The boiler has not been turned on for since late January, 2018. In early January, I had to replace the lower water cutoff and I used the boiler for about 3 weeks after that.

It worked very well. It has sat unused since then. I went down to check on it around Nov 15 when it turned unusually cold here. I saw that the sight glass was empty and I turned on the valve and added water -- slowly -- even though the furnace was cold. Nothing showed up in the sight glass and I ran out of time to watch it.

The next day when I had time I added more water and still nothing showed up. Therefore, I was afraid to turn on the boiler and instead relied upon the heat pump for heat for the next few days before I left the house for a month.

It is possible, then, that the water in the sight glass showed up shortly after I stopped looking at it. Before I left the house for the month, I turned off the circuit breaker for the boiler (at the same time I turned off the one for the hot water heater).

I returned here late yesterday and did not look at the boiler's sight glass but did flip its circuit breaker back on (when I turned the one for the hot water heater).

This morning, Dec 29, wanting to be able to use the boiler for heat (I vastly prefer it to the heat pump), I looked at the sight glass and was surprised to see water in it.

As I said, maybe the water has been in there since mid-November -- hours after I stopped trying to fill it. I realize how confusing this must seem.

On 2018-12-29 by (mod) - is it normal for the boiler to take time for the water to settle and show up in the sight glass when it's off?

Melynda

I'd sure like to see some photos (use the Add Image button, one per comment) to see the Sears steam boiler and each of its controls including the sight glass.

I don't have enough info to be sure but from your description it's possible that

1. you added needed water to the steam boiler - up to the fill line

2. the boiler ran, got up steam, sent steam upstairs, lowering the water level in the boiler

3. condensate had not fully drained back to the boiler when you looked again.

4. You added water SLOWLY - which is smart to avoid cracking a hot boiler with cold incoming water

5. You left town and left the boiler off

6. Condensate from upstairs finally found its way back to the boiler - raising the water level so high that we figure you added water too soon or more than was needed previously.

There could be a clog in the condensate return line that is slowing water return to the boiler.

On 2018-12-29 by Melynda - Sears Roebuck steam boiler with cast iron radiators. No water in sight glass.

Also, is it normal for the boiler to take time for the water to settle and show up in the sight glass when it's off? When its running and I add water it shows up in the sight glass quickly. Thanks again.

I have an old Sears Roebuck steam boiler with cast iron radiators. I have had it regularly serviced, have replaced a part, and had other work done on it, and it works well. It has been off for a year. When I went down to look at it about a month ago, the sight glass was empty so I turned on the valve and added water, watching the sight glass.

After about 20 or so minutes, no water had appeared in the sight glass. I turned off the water. The next day I added more water -- maybe another 10 minutes or so of slow running water. Again, nothing in the sight glass.

I had to go away for a month and I left the electric heat on to keep the pipes from freezing while I was away. When I returned two days ago, I checked on the boiler and saw that the sight glass is nearly full -- only about an inch of space between the top of the glass and the top of the water level.

There's a mark made with a red marker years ago that says water level in someone's scribble. It is about 3/4 of the way up the sight glass. The amount of water in the sight glass is about 3 -4 inches above that handdrawn red mark. I let some water out into the sump area (I hooked up a hose to ghe bottom valve)

-- I let out maybe 2 gallons just now -- and the sight glass level has not changed.

My question is this -- is it safe to turn on the boiler or is that too much water? The boiler adds water on its on -- when it is on -- but I also check it every few days and occasionally add water as needed. Any advice would be very much appreciated. Thank you.

On 2018-12-26 by (mod) - signs of flooding steam boiler - water too high

Kevin

When the sight glass shows water filling the boiler well above the recommended fill-level the steam boiler is flooding.

The result ultimately will be loss of heat - and there is risk of boiler damage as well.

The underling cause is usually a problem with the automatic water feeder valve (or someone over-filling manually) or sometimes a problem with delayed return of condensate to the boiler from the radiators.

See STEAM BOILER FLOODING / SURGING REPAIR

for detailed diagnostic and repair suggestions.

On 2018-12-26 by Edward K. Parker

The water level in site glass exceeds the level almost to the top of the site glass and then furnace turns off. Where is this water coming from

The furnace should work in the reverse as furnace is putting put hear the water shoulddrop in the site glass.

What is the problem when site glass fills up with waterDuring heating. The water must be drain from the furnace everyday to below indicator level.

On 2018-12-17 by (mod) - normal vs abnormal movement of water in the steam boiler sight glass - surging

Interesting question, Paul thank you.

The amount of movement of water in the steam boiler sight glass it would be considered normal or abnormal needs to separate answers.

First is the actual water level in the glass. Water should never Disappear Completely from the sight glass and at the end of heating cycle water level should return to the mark showing normal water level as condensate returns to the boiler and the water feeder valve as water as needed.

Now with respect to surging which may have been your question, you'll see the water level rise and bounce a bit if you feed water to the boiler manually or if the automatic water feed valve feeds water to the boiler. Then it should settle down.

If you see water bouncing up and down like mad the boiler is surging and probably needs cleaning or some other service.

On 2018-12-16 by Paul Reeves

Just how much movement of sight glass water is considered normal?

...

Continue reading at SIGHT GLASS, STEAM BOILER - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see SIGHT GLASS, STEAM BOILER FAQs-4 - more-recent Q&A about using or fixing the sight glass on a steam boiler

Or see these

Boiler Water Control Articles

• BOILER CLEANER CHEMICALS / TREATMENTS
• BOILER LOW WATER CUTOFF CONTROL LWCO MANUALS
• LOW WATER CUTOFF VALVE, BOILER
• LOW WATER CUTOFF VALVE NOT WORKING
• LOW WATER CUTOFF CONTROL MANUALS
• SIGHT GLASS, STEAM BOILER
• STEAM BOILER FLOODING / SURGING REPAIR
• STEAM HEATING SYSTEMS & CONTROLS - home
• WATER FEEDER VALVE, HYDRONIC BOILER
• WATER FEEDER VALVE, STEAM

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