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Summer Boiler shut down/skimming?

Jeff_98 Member Posts: 4
In Jan of 2006, we had our old steam boiler replaced with a new Dunkirk.
The installation team skimmed it on the first day and then came back about a month later and skimmed it again. Since then, I've had to skim it about once a month to get rid of the bouncing in the sight glass. The skimming instructions in manual say that after skimming, you're supposed to let the boiler cool completely, drain all the water and then refill. From what I've read here on the wall, it's not a good idea to keeping adding fresh water. So when I"ve skimmed
the boiler, I've not drained and refilled the boiler.

Now that the boiler is shut down for the summer, would this be a good time to skim and then refill the system?


  • Tom Hopkins
    Tom Hopkins Member Posts: 554
    There are about ...

    Five ways people skim boilers. Some don't work at all. Some work well. None are perfect.

    The "perfect" skim is the one you do AFTER chemically cleaning the boiler.

    1 cup of TSP into the block. Heat to almost steaming (200-210F). Dump the system (returns, Hartford loop, etc.)

    Refill the boiler with clean, cold water. If the boiler feed comes from the hot water heater, change it to cold - only)

    Fire the boiler to 200-210F again and skim until the water is absolutely clear, and the "rainbow" look no longer appears in the bucket.

    Fire to 200-210 one time (to drive of the O2 in the last fill) and you're done.

    About one time in 10, you'll have to do it a second time.

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