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Honeywell PA404A - Pressuretrol question

ksd99 Member Posts: 77
I changed the cut in to .5psi and cut out 1 in my new house, I just found the manual for the unit and I am confused because the PA404A can either be a additive or subtractive - how do I know how it is set up ?
New owner of 1 Pipe Steam Boiler - learning all I can- no real steam pro in S.W. Michigan - if you know of 1 -let me know.


  • Jamie Hall
    Jamie Hall Member Posts: 23,428
    Most PA404A's used and available are additive. One difference which is quickly visible is the main scale; for the additive versions the main scale will be graduated from 0.5 to 9, while the subtractive versions will be graduated from 3 to 15. Also the subtractive versions should have, somewhere on the main scale plate, the words "cut out".
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England