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Moline Steam System

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Maintek
Maintek Member Posts: 7
I ran across a Moline Steam System. It seems mostly intact. Did this type of system use a vacuum pump?

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  • GBart
    GBart Member Posts: 746
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  • Steamhead
    Steamhead Member Posts: 16,886
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    No vacuum pump. The Moline Air Trap, placed at the ends of the dry returns, let air out but would not let it back in. In the days of coal-fired boilers, this would allow the boiler to continue generating steam as the coal pile burned down.

    However, this doesn't work too well with oil or gas firing, since the fire goes out well before all the air is out of the system. Then, when vacuum forms, the air will expand and block the steam.

    Several Wall members are experimenting with small vacuum pumps on ordinary Vapor systems, and the results have been promising, though they're not ready for prime time yet with a contractor-ready package. When they are, I see no reason why the Moline system could not be retrofitted.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 1,218
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    I've "re vacuumed" a number of former induced vacuum systems and they have worked well with a gas fired boiler. I use an Apollo NO 61-104-A1 check valve on the main vent to serve as the vacuum device. On systems we've monitored, the vacuum will drop to about 10 inches between cycles, keeping most of the air out of the system between cycles so on the next burner on cycle there is almost no air to vent. Many of these systems we have modified using the Moline concept of metered steam delivery to each radiator and the elimination or radiator traps. This works exceptionally well.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Jamie Hall
    Jamie Hall Member Posts: 23,419
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    No reason why that shouldn't work just fine. But... check and make sure that the main vent is the only vent, and that some hasn't gotten clever and stuck more vents somewhere off it a dark corner...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • jumper
    jumper Member Posts: 2,282
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    No reason why that shouldn't work just fine. But... check and make sure that the main vent is the only vent, and that some hasn't gotten clever and stuck more vents somewhere off it a dark corner...

    Speaking from experience,Jamie?

    Another idea is to have no vent except for a mechanical evacuator. Some buildings in Toronto worked that way. Did not employ an automatic ejector/air trap like Moline. Instead there was a manually controlled eductor. Building superintendent occasionally evacuated system.Obviously folks in trap & vent business disapproved.