Low water problems

All work and no play makes Bob a dull boy. Just wanted to have a little break so I took myself and six of the guys from the shop down for a Kansas City Royals game. Since we had seven people I went ahead and booked a limo ride and that way we could indulge in some adult beverages and not have to worry about the drive home.
There are a multitude of things that can cause low water issues. First you need to understand that you have to lower water cut outs, a lower cut out and an auxiliary low water cut out. These can be a float or a Warrick probe. Your auxiliary low water cut out should cut out 1 inch before all visible water is gone from the sight glass. Your low water cut out should be about an inch and a half to 2 inches above that.
One major cause of lower water alarms is a dirty Warrick probe. Your probe needs to be clean cleaned and inspected yearly. After the probe has been cleaned you should take a multi meter set it to the resistance and make sure you have conductivity throughout the probe. If the insulation is cracked and needs to be replaced. This will cause a short and your boiler may not trip out on the when it is in a lower water condition. Low TDS will also cause your low water probes to give a false low water condition. TDS or total dissolved solids should read about 3000 ppm. If it’s too high it will scale up and cause large bubbles instead of the small steam bubbles that you would like. If your boiler is too low then your low water cut out probes may not work because it cannot pass current between the common probe and you’re sensing probe.
Floats should also be pulled and cleaned yearly. They should be inspected for damage. The bowl that float sits in needs to be free from mud and scale. Floats and probes should be blown down once a shift or every 8 hours of operation.
Another common problem of low water is a pump that isn’t working properly. The pump could be cavitating or the motor running backwards. There’s a multitude of issues that could happen with your pumps. The best way to test your pump is to have a gauge on the outlet side and dead head the pump for a short period of time. All boilers should have a check valve right by where the feedwater enters the boiler. If this check valve is not functioning properly you overheat your feed water or DA tank and cause cavitation in your pump.
These are only a few of the basic things that go wrong to indicate a low water problem. I hope it helps.

Why the Boiler in the Tofu Restaurant dose not Have Water

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Above is a photo of the A Fulton boiler system.  The components from left to right are as follows:   feed water tank with the pump mounted on the bottom of it, boiler, and blow down tank.  There is a water softener that is not show in the photo to the left and forward of the feed water tank.  It is not shown because it had nothing to do with the fault at first glances revealed.   This fact will be explained latter.

The task at hand is to find out why the boiler is not filling with water so that it can generate steam.  First a basic overview of what the system is meant to do.  City water is fed into the water softener.  From the softener the water is delivered to the feed water tank.  The pump under the feed water tank is tuned on when the boiler’s control system is near a low water state (Low water state will shut down the boiler for safety reasons).   Therefore, overcoming the pressure of the boiler and filling it with water.  Lastly the blow down tank is used to cool down the water and steam in the case of draining the boiler or blowing down the water callem. 

The history of this system is that RF Macdonald Co has had many call backs of this fault.  Technicians in the past few mounts have gone out to the sight turned a valve or pushed a rest button and been on there way to the next job or home.  I was encouraged to do the same after talking to the last technician to fix the problem.  The truth is that this boiler is still under warranty, and RF MacDonald is not making any money off services work.  More importantly the owner of the tofu restaurant needs this boiler to operate because he can not make tofu without steam.  Steam can not be made without water in the boiler.

Result-Center Troubleshooting

The boiler will be filled with the proper amount of water when the control system should call for water, if:

It is a good unit.

There is a complete and proper path for the water to flow.

The boiler is calling for water.

There is proper voltage to the system.

All control setting are set correctly.

First Glance

Feed water tank has water

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More then likely everything is good to the feed water tank.

Pump is not on

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It would appear that the boiler is not calling for water.

Boiler will call for water if

The controls are set properly.

The proper voltages are applied to the circuit.

The control panel is a good unit.

There is a complete path from the control to the pump.

Trouble shooting reveled that the relay that energized the pump contactor were not making a complete path.

I rest the relay, the pump turned on, the boiler filled with water, and began to make start the process to make steam.

Why when I rest the relay did the pump turn on?  Did it shake loose?  Is there a loose wire?  Or is it something else?  The only way to know was to watch the system run.   

The boiler ran well used up enough steam for the control system to turn the pump on to put more water into the boiler.  The pump did turn on, but looking at the sight glass I could not see that the water was going into the boiler. I lessoned to the pump and it sounded like the water in it was boiling.  While lessoning to it I placed my hand on the feed water pipe to feel for flow.  All I felt was a lot of heat.   There should be no heat on that line because the feed water is cold and there is a check valve between the pump and the boiler.   Yes the only way that can happen is if the check valve is a bad unit and the reason resting the relay worked is because it reset an overload circuit in the relay.

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The shiny part of the brass in the photo to the left is were it buy-passed. 


In conclusion with my new techniques in troubleshooting and a basic knowledge of how boiler feed water system work I believe that I have solved this problem for good.  Before taking this class feed water problem were some of the hardest thing for me to troubleshoot.   In fact when I got told to go to this job I was not sure I would be able to help because I do not no much about pumps and there was no documentation on sight.

There was one more major problem I found in the system when I blow down the boiler.  It blew hot steam right into the kitchen under the cook feet.  It had nothing to do with the problem, but it is a safety concern and kind of interesting to summarize in my conclusion.  I could not believe any one would pipe hot steam into a place were people could get burned.   The problem was not were it was pipe, but that it was still hot.  I called my boss and he expanded that a blow down take mixes the hot water and the steam with cold water to cool it off .  When I Looked at the blow down take there should have been a thermostat and cold water piped in, but there was not.

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This job thought me a lot.   Of cores I learned more about the way things work, but it showed me to look at the whole picture, and that I can do a lot more then I think I can if I take the time to put it into a logical order.

Pilot flame problems

One of the most common faults I see is the pilot flame will not light. So this means that the boiler goes though it pre-purge, then tries to light but the burner management system says flame failure while trying to light the pilot, or something to that effect.

One of the first things I will do is see if you can see the flame though a sight port. If there is one in the back as there often is, that will probably give you the best view.

If there is a nice pilot flame then the next step is to take off the flame scanner and look though the pipe that the scanner was connected to. This will show you if something is obstructing the line of sight for the scanner. It is usually obvious. If nothing is in the way and you see the flame the scanner is probably bad. You can conform this by holding a light in front of the scanner and seeing if it lights up and shows a flame signal on the burner management system.

If you look in the back and could not see a flame or a spark, you need to pull the pilot assembly. If it has soot on it, clean it. Soot can make a short across the electrode and the pipe that is being used as the ground. After you have cleaned the pilot, you should set the gap for the spark 1/8” gap and ½” back from the end of the pipe. This has worked the best for me. To test your spark: set pilot assembly on a stable platform and hook the ignition transformer up to the electrode. Make sure the pilot tub is grounded and shut off pilot gas. Start boilers and watch to see how your spark looks. If it dose spark, blow on it. See how the ark moves and that it ark about a half of an inch. If it doses not spark or just small, your ignition transformer is probably bad. If it sparks in the wrong location, the porcelain igniter probably has a crack. Remember that the spark is six thousand volts. Do not get shocked.

This guide and a bit of good common senses should help you correct many pilot problems. At lest if you have to call the boiler technician now you know it is not a simple fix that you could have done.


So before I get to the meat of this sight I need to say that you are responsible for your own actions. If you hurt yourself or break something on the boiler it is your fault. I have spent years learning and working on boilers. I have not spent years leaning or teaching others how to do this, so don’t do anything that you are not comfortable with.

In all honesty a boiler is extremely dangers. Most things are done better by a professional like myself. This be said I know that many of you will work on your boiler yourself and I hope my tips help you do it safely.

As far as setting combustion on a boiler, the normal maintains person should never try to adjust the main air or fuel valves. You could soot your boiler up very easily, make it flame out, or even force your boiler to BLOW UP. Combustion should never be adjusted without a calibrated analyzer that reed oxygen, carbon dioxide, nitrogen oxide, and nitrogen dioxide. When I say calibrated I mean by the factory or with certified gasses.

I have seen an operator look at a boilers flame and rightfully determine that the boiler is running rich (to much gas). To correct the problem he took the linkage off the air damper and opened it up. This caused a five-foot flame to shoot out of the front of the boiler. If a flame is rich that means there is more fuels that then there is air to burn, so giving it the air it wanted causes a ball of fire. The best course of action would have been to turn off the boiler and call a certified boiler technician. The secondary option would have been to close the gas valve.

The last thing I would like to cover for safety today is the boiler going into a low water condition. In the extreme case that you see no what in the sight glass and the boiler is still running, do not add water to it. For example if someone left the feed water valve closed and the boiler did not trip off on low water or Aux Low water. If you open the feed water the boiler may blow up. Water expand sixteen hundred time is size when it flashes to steam. So a gallon of water will deliver the amount of force of a stick of dynamite.