Low Water Cut Off

mcp1

I have a gas fired steam boiler, that was installed about 7 years ago. I have noticed that my automatic water feed keeps supplying water to the boiler. I closed the valve on the automatic feed (both valves, main & Bypass), because the sight glass is 3/4's full with water. When I closed the valves last night the gauge on the feed was 17 gal. This morning I checked the feeder gauge & it was 39 gal, with the valves closed to the automatic feeder. How is this possible & why would the Low Water Cut Off keep calling for more water when the sight glass is 3/4's full?

Big Ed_4

What sets the gallon gauge is a clock with a known flow rate (not a flow meter ). The low water cut off is sending the feeder a signal to add water ..The issue is in the LWCO. . It could be A dirty , teflon tape or bad probe . May be a bad LWCO . I would replace the LWCO complete ...

mcp1

Thank for the response Ed. Why Would the gauge on the automatic feed almost double gallons when the valves are closed?

Jamie Hall

mcp1 said:

Thank for the response Ed. Why Would the gauge on the automatic feed almost double gallons when the valves are closed?

Every time your low water cutoff calls for water, the indicator on the feeder will count. It does NOT actually measure the flow -- just has it been asked to provide water.

Now... having said that, as @EBEBRATT-Ed said either you have a problem with the low water cutoff itself -- or you have a boiler which is misbehaving and dropping the water level too far when it is firing. Neither one is good, and you should have the situation checked and fixed as soon as possible. For starters, go down there when the boiler if firing and observe what the water level is doing. Note: if the water level doesn't fluctuate at all when the boiler fires -- if it is nice and steady -- it is possible that the openings to the sight glass from the boiler are clogged. You can check that by deliberately lowering the water level briefly with a blowdown drain; the glass should respond. If the glass isn't responding, the is very dangerous. The boiler should not be operated in that condition.

mcp1

The water in the sight glass does NOT seem to move.
The other day the sight glass was completely full & I tried to drain water out of the boiler & there was no movement within the sight glass.
How do I unclog the sight glass, if it is clogged? Where is the blow down drain?

Jamie Hall

If the water in the sight glass does not move, you have an extremely dangerous situation. You need to clear the openings from the sight glass into the boiler. There are various ways to do this, depending on the exact installation; a picture or two of the sight glass -- including the valves at the top and the bottom -- would help.

In the meantime, I'd be very unwilling to run the boiler, since you have no idea how much water is actually in it.

JUGHNE

You may not have drained enough water too lower the level to be visible in the glass. There are several inches of space above the sight glass that could contain several gallons of water.

With the boiler off:

On the very bottom of the site glass assembly is a small drain port.
You loosen the smaller fitting to open a very tiny drain port.
Close the bottom glass valve first. This way you drain the glass only, not the boiler.
If you get that loose and water dribbles out the level should drop.

Close the drain and open the lower glass valve. The water should bounce back up to previous level.

You could do this several times to loosen up crud in the lower valve connection into the boiler.


The water feeder does not know if it is even hooked up to water or not.
It is simply a timer that opens an internal valve and counts and displays the time of doing so.

Cleaning it's probe would be the first easy thing to do.

A

mcp1

Thank you guys, i will post some pictures of the sight glass

mcp1

mcp1

JUGHNE

The drain port looks chewed on, did you get it open?

mcp1

I opened the drain port & drain the sight glass empty. When I plugged the port & turned the bottom valve open it refilled the sight glass to about a 1/4 full.
I have the boiler off now. Should I wait about an hour to refill to 3/4 full?
Im in NY & the outside temp is around 20 degrees

mcp1

Thank you
This is the water level it refilled to, when I plugged The drain port and opened the bottom valve.  It’s about a quarter of the sight glass. 

Should I slowly add more water until the sight glass is about 3/4’s full?