excessive water in boiler(Steam heat) causes water hammer, is my auto feeder broker?

lakefruit

Hi All

I am puzzled by my stream heater's recent problem. It starts to have severe water hammer which it never had before. Yesterday in the morning, I checked the water level, it is normal and steam runs fine without water hammer. But at night, it banged really loud. I then checked the water level again. Man, it is over the roof! I drained about 10 buckets of water out of it before water level back to normal!!!!! No wonder it water hammered like crazy, water is spilled over to main.

Can you guys help us diagnose this problem? I can't think of any other reason other than a bad auto feeder module? Is there any reason that could cause water level in the boiler to raise?

Thanks

JohnNY

It's very likely that the problem is with the low water cut off device. It's probably stuck calling for water from the feeder even though it's full.

lakefruit

@JohnNY Thanks, where is the low water cut off located? Is it something a regular joe like me can take care of? Should I schedule a plumber to come and take a look? Thanks

JohnNY

If you can post a picture of the side of your boiler where all the controls and electronic goodies are, I'll point it out to you. It's not often a user-serviceable item but let's see what we can do .

lakefruit

Thanks, @JohnNY Here are pics

lakefruit

I noticed that during morning heating cycles, water level doesn't rise much and no water hammer. It only happened at night when it is colder and Boiler runs longer.

JohnNY

Are you flushing water through your system regularly? You need to flush your low water cut off bi/weekly or so to keep it functioning normally. There's a float inside that tells either the boiler to run or the feeder to feed. When it inevitably gets all mucked up, it gets confused and gives the feeder/boiler the wrong message.

lakefruit

@JohnNY, I flush low water cutoff once a week using the pull up handle.

If I understand you correctly, I should drain boiler, remove lower plug, clean it and install it back?

JohnNY

Yes, you could do that but be careful, your hand will be right in the line of draining filthy hot water as you remove the plug. Flush some cool water through the boiler and flush handle first, then remove the plug. Lift out and use the brass rod mounted next to the vertical glass tube to poke around in the LWCO once you've removed the plug to loosen up the float and anything else in there. Put a bucket under the open port and manually add some water to the boiler to flush it out again without using the handle.
When you're carefully poking around in there, notice the clicking sound you can make to simulate the float reacting to what's normally the changing height of water in the device.

lakefruit

@JohnNY , Thanks a lot. I just did the flushing. I will report back if that would resolve the problem.

nicholas bonham-carter

Try to do this flushing with the boiler running, so you can be sure it cuts off the burner. When you flush it even regularly, the water will first be murky, and then runs clear as all the rust particles are washed out.
It would be easier for the first timer to do this flushing, and checking for cutting off, numerous time, over several days, before removing that plug, which may have been in place for many years.
It looks as though the valve to the auto-feed is closed.—NBC

JUGHNE

How do you heat your domestic water for faucets etc?

EBEBRATT-Ed

There is a tank less water heater in that boiler. Can't tell from the pictures if it is disconnected or not.

That could be the issue

lakefruit

@JUGHNE @EBEBRATT-Ed Tankless water heater has been discounted earlier last month.

lakefruit

@nicholas bonham-carter I have auto feeder water valve half open. Should I leave it open entirely? It has been set at half open since I moved in. I have never had any issue before.

lakefruit

@JohnNY Heater run a couple of times today. So far so good. However today is not too cold, so each time boiler was not running for long. I need to see if it still creates problem when boiler runs longer.

Fred

You can turn the auto feeder fully off for a couple days and see it that resolves the problem. It is possible water is leaking past the internal valve in the water feeder.

I see you have a on McDonnell Miller #67 the boiler? They need to be taken apart and cleaned out every year or so. The side walls and floor of those units get a build up of crud on them and that will cause the float to rub and hang up on the side walls and, if not cleaned, will eventually cause enough build up on the floor of that unit to prevent the float from dropping down enough to shut the boiler down, in the event of a true low water situation. When you do that, you need to buy a gasket set for it. It is also remotely possible that the copper float inside has a pin hole in it and is water logged but that is less likely or it would call for water constantly.

lakefruit

@Fred , Thanks for the advice.