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Pressuretrol Setting Honeywell PA404A

Ken_40 Member Posts: 1,320
Five PSI?

That's about four more than required. Wasting fuel big time.

Fawgettabowt what the "dial" on front says. It is a guide, not the actual setting. The white wheel inside that you state is set at "1" is correctly set.

The secret to these things is hidden by fact that they are grossly insensitive to the pressure normal house heating steam boilers are designed to operate at. The norm being between 1/2 pound and 1-1/2 pound, frequently symbolized as '#'.

Start by unscrewing the top screw until the little "blade" thingy is half a matcthbook thickeness away from dead lowest point in the slot/raceway. At that point your as close to a satisfactory setting a homeowner might get to (without destroying the 404).

The correct "solution" is to replace the 404A with a vaporstat. These are designed to very accurately work in the 1/8 to 2# range with exacting on/off control.

Cost? About a buck 'n a half wholesale. Around $300 installed by a pro who has more than a clue (plus travel time). The investment would pay for itself in a year.

Let us know how you make out lad.


  • Emmett McGuire_2
    Honeywell PA404A - Diff set to 1 but cuts out at 5 psi

    My boiler is building up pressure to 5 psi on cold days before it cuts out. My pressuretrol's indicator on the front panel is set to the lowest setting of 0.5 psi.
    The internal differential dial has no mark or arrow to indicate its "set" position. Currently, the dial is set with 1 facing front. Does mean it is set to 1?

    If the differential IS set to 1, then what could be causing the boiler to continue running after it reaches 1.5 psi?

    In addition, the boiler seems to require more water than it has in years past. Typically, the water in the sight glass would rise to about the half-way mark. This season, the water fills the sight glass about 3/4 of the tube. I am also experiencing much more hammering in the system much longer into the heating cycle.

    Thanks, Emmett
  • Dan_29
    Dan_29 Member Posts: 111
    pressuretrol problem

    Is your pigtail plugged? Is the pressuretrol old? All electrical devices fail sooner or later. If your pressuretrol wheel reads 1 the cutout point at 1.5 psi should shut off the boilerun until it drops to the .5 cut-in point.

    Do you have an water autofeeder that is falsely releasing makeup water due to a false reading on your low water cut-off device-probe type? This may account for why your water level is too high at 3/4 level rather than 1/2 level in the sight glass. Overfilling the boiler may cause banging.

    A vaporstat is a great idea, however, make sure your steam supply lines (to the radiators) are quickly vented of air.

    A call to a pro might be a very good idea.

  • Emmett McGuire_2

    Thanks for your fast responses...

    I have a service contract with my fuel supplier, however, they don't seem to know steam very well.

    My pigtail was plugged last year at which time my service company replaced the Pressuretrol and cleaned out the pigtail (they initially tried to replace the pigtail but all the pigtails they had on hand were too small so they resorted to cleaning out the plugged pigtail). The symptoms I experienced with a plugged pigtail were that the furnace would not fire at all - the plug prevented the contacts from meeting.

    I replaced my main vents with Gorton #2s last year and all radiator vents are functioning properly. My heat is excellent and all radiators get equally hot at the same time.

    The low water cut-off appears to be functioning properly as it will only fill when there is only a trace of water in the bottom of the sight glass.

    As an experiment, I drained the boiler from the 3/4 full point to the 1/2 point on the sight glass and observed the next heating cycle. It seemed that as the pressure increased to the 2-3 psi range, the visible water level decreased to the minimum line, the boiler stopped, the auto-fill opened the valve for about 45 seconds bringing the water level up to about 1/4 to 1/3 of the sight glass, and then the boiler fired up again - all of which seems like the controls are operating correctly. When the heat cycle is satisfied and all the condesate returns to the boiler, the water level in the sight glass reads about 3/4 full.

    Is the higher pressure creating more steam, thus, requiring more water? The boiler is a Burnham V75.
  • jim_110
    jim_110 Member Posts: 24

    Emmett call that "service company" and tell them the pressuretrol they installed last year is NOT functioning PERIOD.They should replace it and check the pigtail again.Regardless of your other concerns that control should cutout at 1.5 lbs . Pressure at 5lbs is detrimental to your system's ability to function properly.Your pressuretrol is THE MAIN control to limit your pressure, after that it's your 15lb safety relief valve and you DON'T WANT TO GO THERE.
  • Vermonter
    Vermonter Member Posts: 57

    I had the exact same pressuretrol on my system and even though the little metal tab pointed to "0.5PSI" it ran up to 5psi before I adjusted it.

    I took off the cover and lowered the set screw until the lower shoulder of the set screw lifted off the body of the pressuretrol (tough to explain, when you do it you'll see what I'm saying). Then I tightened it down about 1 full turn. This helped quite a bit more than I expected but I still ended up installing a vaporstat.

    I wouldn't rely too much on what the gauge says inside about +/-1 psi. Odds are good that it's fairly cheap and not *that* accurate.
  • sphen
    sphen Member Posts: 9
    is there a "fine adjustment" other than the low and diff?

    hi there -- i know the answer is most likely going to be - "you should get a new one" but i am currently in the search for a non-"knucklehead" boiler guy and in the meantime want to make sure things dont get worse....

    i noticed that the pressuretrol is not working properly... i have double checked the settings on it but as the psi gauge goes up (after he pigtail, before the pressuretrol) even though the pressuretrol is set to .5 on the front and 1 Diff, pressure will go to 5.5 or so until it shuts off. the boiler will kick in before it drops all the way down too.. seems like it is just out of calibration or something to me. are there any other adjustments on the pressuretrol i can work with before i get another one in there? i would sit by it and make sure it goes properly through a cycle and adjust as needed. higher that 5 psi starts to scare me...

    thanks for the help -- and if anyone knows anyone knowledgeable with boilers in new haven/fairfield country CT let me know!
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