My employer has a one pipe low pressure steam heat system. Some of the
system is fairly old. One of my jobs is to "blow-down" the boiler each week
during the heating season. Lots of rust! Recently we had to have a
backflow prevention valve installed and I asked the tech doing it if there
was some kind of anti crosion compound we could put into the make up water.
He said the way to deal with the problem was a system that continually adds
chemicals to boiler water. He estimated around $1k. I would appreciate any
Are you blowing down the low water cut off or blowing down the boiler
itself? It's essential to blow down the LWCO in order to keep crud from
building up and fouling it but take it easy with blowing down the boiler.
All the water you lose must be made up with oxygen rich fresh water. This
tends to accelerate rusting of the boiler and pipes.
Having a chemical systems in the make-up water is a must. You can contract
a company like AquaChem to come in and test your water, and then they will
recommend the proper chemicals. They usually also install a water meter
that will deliver the proper amount of chemical for so many gallons of
make-up used. The will also leave behind a test kit for you to measure
critical levels in the water.
Blow down is an absolute must. In my past experience in Milwaukee County, I
did it daily on all 3 150hp LP boilers. Even in a system that was
chemically sound, I still saw small amount of rust, but it sound like
nothing you see. I would do it more often than once a week until you can
chemical added to your make up water....
Another common mistake: When the heating season is over, and the tank is
opened up, and the water side of the tubes are exposed, you will probably
see rust "pillows" on some of the tubes. DO NOT remove them! You can
almost guarentee to get pin hole leaks into the fire side of the tubes,
requireing repair from a cetified welder.....Correct the pillows with water
Original piping, of course - no way are they still running the same tubes in
the vessel. Boiler tubes do wear out, even with a good chemical program.
And are replaced as needed. I have seen many boilers re-tubed with good
chemical programs, and less than 30 years of service.
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