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setting differential admustment dial on Honeywell pressuretrol

lindera
lindera Member Posts: 26
in Thermostats and Controls
It is not clear to me how to set the white dial inside my PA404A Honeywell pressuretrol.  I see the numbers on the dial but I don't see a pointer to line the numbers up with.  the literature on their site has a very dark black and white photo that doesn't help.

Thanks.

Comments

  • will smith_4
    will smith_4 Member Posts: 259
    L404A settings

    If you look at the face of the control, you will see one side marked as "Main", and the other marked as "diff is subtractive". There should be metal tabs in each of these sections which will move as you adjust their settings, using the slotted screws on top of the control itself.

    For example, if you set the "Main" to 1 1/2, and the "diff" to 1, the boiler will cycle on if the pressure drops to 1/2#, then cycle off when it gets to 1 1/2#.

    If you don't have the metal tabs as reference points, the control might have been made 5 minutes before quitting time!

    All the best
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