The boiler problem almost everyone has experienced
It’s the end of the day and you have one pair of pants to finish. You dress the topper, hit the button and suddenly there is water pouring out the legs of the pants. Or maybe you were touching up a white dress and the iron spits out some rusty water.
It’s enough to make a preacher swear! It only happens once in a while, but it always seems to be at the worst possible moment.
You may be suffering from foaming or surging. The water in the boiler ‘surges’ out of the boiler, down the pipes and into your machine. It overloads the trap and comes out when you press the button for live steam.
A machine with a closed chest (e.g., a collar-and-cuff press) is not bothered by a little surging. It is only machines that inject live steam that have problems (form finishers, hand irons, etc.).
If you watch your sight glass, you will see the water level move up or down several inches in a matter of seconds. When the burner shuts off, you may see the level drop. Or if there is a sudden demand for steam, the water level may jump up for a few minutes while the water foams and then drop as the boiler runs out of water.
After that, the level usually drops so low that the pump takes several minutes to catch up and the steam pressure drops off.
VIDEO 1: Shows the water level in a boiler rising several inches as the water starts to foam up. The burner had just turned on. At the end of the video you can see small grains of scale floating on the water.
Foaming is usually caused by excessive contaminates in the water. It may be oil from some recent pipe work. It may be scale – minerals left in the water after some of the water has evaporated. It may even be a buildup of boiler treatment. Some people think that if a little boiler treatment is good, then a lot is better. That is not true!
Our water in Alberta is hard. It contains dissolved minerals. Those minerals are dissolved rock. When you evaporate the water, the ‘rocks’ are left behind. Soft water is critical for proper boiler operation, but you still need to blow down the boiler. The more water you evaporate, the more minerals (dissolved solids) are left behind. Removing some contaminated water and adding fresh water will keep the dissolved solids at a reasonable level.
Think about a boiler as a pot of pasta. The longer it boils, the more concentrated the water gets and the longer the bubbles last. If you evaporate enough water, you will be left with a thick ‘stew’ instead of water.
That is what happens in your boiler. If you are not removing enough contaminated water and adding fresh water every day, you will end up with a foaming issue. This problem can also be caused by too small a boiler or piping problems.
Occasionally there is a problem with the blowdown piping being plugged. You may still be blowing the boiler down, but there isn’t much water leaving the boiler so the contaminants still build up.
VIDEO 2: Shows a sight glass that hasn’t been blown down for a long time. You can see the sludge in the water when it was blown down. The glass and water column need to be blown down every day.
Cure correct amount of boiler treatment, correct amount of blowdown, soft water
If you think you have a surging problem the cure is simple. Start with fresh water. To do that, shut your boiler down. Open the bottom blowdown valve a little and wait till the pressure gauge reads zero. Refill the boiler with clean water and see if the problem is fixed.
If that cured the problem, then you need to decide what caused the problem to start with. Was it too much boiler treatment? Or not enough blow down? You’ll have to decide which it was in order to fix the problem.
Check the amount of boiler treatment you are using. What does the manufacturer recommend? I would suggest a little less is better than too much. Confirm with the person who is adding the boiler treatment. Do they actually have a measuring cup? And are they using the correct amount?
If the treatment is okay, how long are you blowing the boiler down for? If you blow it down longer you might waste a few gallons of hot water. That doesn’t cost much compared to the problems you are having. Increase the amount of blowdown for a couple weeks and see if that fixes the problem.
Blow down the sight glass, then the water column and finally the bottom blowdown. In Alberta, we usually recommend a total blowdown time of 45–60 seconds.
Most dry cleaners use a one-shot boiler treatment. No one is monitoring the water condition, so it is better to do a little more blowdown than necessary. Better to have a little too much rather than too little.
This is one problem that is completely an operator issue
This problem is completely operator error. And it’s easy to fix. Before you assume there is a mechanical problem, empty the boiler and see if the problem goes away for a couple of days. If the problem goes away, it was not a mechanical issue. You just need to make a change in the amount of boiler treatment you are using, or increase the blowdown time.
If that doesn’t work, of course, it’s time to call in a technical person to go over your boiler and get it back up and running properly.
Kevin Marois founded Calgary-based Integrity Mechanical in 2003 to serve plants in Western Canada. He writes on issues related to equipment, its purchase, maintenance and use.
You can reach Kevin at firstname.lastname@example.org, or via his website, www.imicanada.ca.