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Dual Pressuretrols

CRP Member Posts: 5
Can't seem to find my last question so here it is again...

I have a oil fired steam boiler that has two Honeywell PA4004A 1033 pressuretrols on the same pigtail and wired in series. Neither one is manually resetable.

The right pressuretrol states CUT IN and has a range of 0.5 to 9.0 psi, and has an additive differential wheel inside.

The left states it is a CUT OUT and has a range of 3.0 to 15 psi, it has a minus (subtractive) differential wheel in side..

There are just two wires coming from the burner and these are then wired to the two pressuretrols in series.

So my question is what should the settings be? One must be a safety back up. I'm having trouble with the wired in series aspect. If one goes bad then the other will take it's place. So should they both be set to act as low pressure shut offs?


  • CRP
    CRP Member Posts: 5
    RE:Dual Pessuretrols

    After looking over my notes and pictures, I come to the conclusion that the pressuretrols may be wired in paralell. This is what happens when the same color wire is used to often! Makes them puppies hard to trace.

    Still wondering what you all think.

    Thanks again, Ken
  • BobC
    BobC Member Posts: 5,473
    edited January 2011
    2nd should be a safety.

    They had better be wired in series, unless it is a dual firing setup (high - low). The chance of it being an oil fired dual firing setup are nil on a residential boiler.

    The idea is to have one control the boiler for normal low pressure operation and the other is a backup to shut things down in case the other pressuretroll doesn't cut out. It would be best if they were on seperate pigtails so one clogged pigtail didn't negate the safety factor.

    The low pressure one would be set to cut out at 1.5PSI and back in at 0.5PSI. The backup would be setup higher (5-10PSI) just to backup the primary.

    What does your pressure gauge read just before the boiler shuts down?

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
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