STEAM BOILER ADDS WATER

Matt Weippert

I have a one pipe steam boiler in my 105 year old home. Recently when the boiler runs while it is producing steam the water fill kicks in adding water. This can happen either 1 or 2 times depending how long the boiler is running. I replaced a couple of vents that were continually hissing and I don't see or hear any pipes leaking which would indicate steam being lost to a leak.

Any thoughts as to why the boiler would be adding water like this?

BobC

Adding water

Either that water is leaking out or it's not coming back after being turned into steam.



Do you have any return pipes buried in concrete? It would take a pretty major steam leak to cause a boiler to add water once or twice a steaming cycle. When the boiler is making steam, step outside and look at your chimney, do you see a large plume of white coming out of it? If that plume is larger than your neighbors you may have a leak from the boiler into the firebox and the leaking water is being turned into steam. 



One way to detect this is to overfill the boiler well above the sight glass and let the boiler sit for a few hours, This should be done when the boiler is cold or just warm and can remain off for several hours. if there is a leak the water level will fall on it's own and you will see water around the boiler or inside the firebox. When your done drain the boiler down to it's normal level and fire it up to make steam, this is to drive off any oxygen in the new water.



The other possibility is that the boiler return is clogged up and not letting the condensed steam come back. This usually shows up as the boiler becoming overfilled a few hours after a heating cycle.



Bob

JeffM

slow return

One of your return pipes may be partially clogged, so that condensed water from your steam is slow to return back to the boiler. If you can shut off the auto-feeder, watch the gauge for a cycle and after the boiler shuts off, see if the water level comes back slowly to normal. If it does you have slow (clogged) returns - if it stays low until the next burner cycle you may have a leak.

Matt Weippert

FOLLOW-UP

Last night I watched the boiler as it ran and I am now wondering if it is an

automatic feed problem.  As the boiler ran and was building up steam the automatic fill kicked in twice to add water.  The odd part was that I was watching the sight glass and there seemed to be sufficient water.  The water level in the glass had a slight bounce and after the boiler ran for about 15 minutes the level did drop a bit but not low enough to shut down or add water but the automatic feed kicked in anyway. 

When the boiler shut off the water level dropped and was no longer visible in the sight glass so the auto-fill added more water.  I watched the glass for about 20 minutes after the water fill stopped and I could see it gradually rise so there is definitely a return on the steam.

 What would cause the feed to kick in? 

A slight bounce in the sight glass water is normal....correct?

The water fill kicking in while I'm producing steam will cut down on the heat to the radiators, isn't that right?



One final thought:  many years ago the end line in the basement had one air vent.  When the system was serviced by a 'steam expert' he took that out and added a pipe that included 3 air vents.  When the boiler kicks in I never hear them hiss out any air.

Should they be replaced and should I go back to 1 vent?

BobC

water feed

When you say the water eventually comes back, does the boiler end up being filled too high? If it doesn't you are losing a lot of water and that boiler will not be long for this world if it continues. A steam boiler should only need water every few weeks at most. If the boiler did not end up overfull you have a leak and it must be found. Try shutting the auto feed off and sit and wait for the level to drop, when it drops enough the boiler will stop. See how long it takes the water to come back and if ALL of it comes back.



Some bounce in the sight glass is normal but if it all disappears at some point you have a problem. Post some pictures of the boiler and the piping around it.



Are you sure there aren't any leaks and have you tried overfilling the boiler to check for leaks in the boiler itself?I assume you have a float type low water cut off, has it been flushed a couple of times a month and has it ever been disassembled and cleaned - they tend to fill with crud over time if they aren't flushed regularly.



The air vents may well be working, try holding a piece of paper up to them to see if air is escaping, be careful using your hands because steam will burn you. It's important that the air in the steam mains get out hast, whoever replaced the single vent with three was right on the mark. have him look at your system and find out where the water is going.



Bob

nicholas bonham-carter

Over-feeding?

Test your LWCO for cutting off the flame on low water, And valve off the feeder, so it cannot add water, and see if the boiler will run low. This test is best done when you are around to watch it. Another reason for slow returns could be an old vacuum radiator vent still on one of the rads. This will keep the water from coming back out of the radiator, at the end of cycle, and will starve the boiler.--NBC

Matt Weippert

UPDATE

Hard as I try I cannot find a steam pipe leaking.

Water does return, slowly, but it does return.   The boiler water feed adds water twice while the boiler is running.   This only started about 2 weeks ago.  I have not had time to fill the sight glass/boiler and let it sit to see if it drains.

Additionally I cannot tell if the mainline vents are working. I did hold a piece of paper to them but I do not see any movement.  There are two(2) sets of 3 vents.  They heat up but I cannot tell if they are drawing out the air.

I have attached some boiler pictures.

nicholas bonham-carter

Another cause of low water

If the pressuretrol is not functioning due to a clogged pigtail, and the pressure rises (unnoticed because of the useless original gauge), then the water will be forced out into the wet returns up to a height corresponding to the pressure in the boiler. With pressure out of control, the water can stack up several feet, starving the boiler.--NBC

Matt Weippert

OVERFILLED AND SHUTDOWN

As suggested I overfilled the boiler and shut it down for about 1-1/2 hours. The water level dropped about 1" while the boiler sat idle. Odd thing is there is no water around the boiler and I do not see any evidence of water in the fire box.



Any idea where the water is going?

Matt Weippert

OVERFILLED AND SHUTDOWN

As suggested I overfilled the boiler and shut it down for about 1-1/2 hours. The water level dropped about 1" while the boiler sat idle. Odd thing is there is no water around the boiler and I do not see any evidence of water in the fire box.



Any idea where the water is going?