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Subtractive Pressuretrol Control

I have a Burnham Low Pressure Steam Boiler Model MST396.  The burner has a Subtractive Pressuretrol as seen in Dan's Book on p. 124. The burner technician has set the control for the Differential (left control) at 1. The control for the Main (right control) is set below the marking for 1 and half way to the bottom of the register.  I don't understand this setting for 1/2 lb of pressure!


  • vaporvac
    vaporvac Member Posts: 1,520
    Repost to steam

    Try reposting this to steam for abetter response.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
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