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Pressuretrol Issue

Fred Member Posts: 8,541
I have a one pipe steam system with 15 cast iron radiators spread over 2 floors. This morning I put a new, 1-3lb., low pressure gauge on it, per an earlier posting. I had the boiler down for a couple hours so when I started it up, it had to bring the house back up to temperature and ran for about an hour and 15 minutes. Normally it only runs for 15 to 20 minutes.My problem is, while watching the new gauge, the pressure actually got up to 3psi before it cut out. I have the pressuretrol set at .5psi cut-in and 1psi differential so it should have cut out somewhere around 1.5psi. I cleaned and filled the syphon tube while installling the new gauge (on the same syphon.  My question is: Does this indicate a defective pressuretrol or are they simply that sloppy? Does it make sense to replace it with a vaporstat or is there something I can do to get better control with the pressuretrol? I think I have good venting on the mains as I only got 1 oz. of back pressure during the venting cycle. Any advice is appreciated. If I shoud put a vaporstat on, can someone tell me which one I should use? Do they have to be calabrated and, if so, is that difficult? My current pressuretrol is a Honeywell PA404 A 1033. 


  • Jamie Hall
    Jamie Hall Member Posts: 21,111
    I seem to recall

    from somewhere that pressuretrols have a calibration adjustment on them.  They do get out of whack, and if it is on the same pigtail as your gauge, they really should be in closer agreement.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Fred
    Fred Member Posts: 8,541
    I don't see any way to calibrate

    I looked at my pressuretrol again and also the installation instructions that came with it. There does not appear to be any way to recalibrate it. I watched my boiler run a couple normal cycles (where it was not trying to bring the house temp up 2 or 3 degrees) to see where the pressure was when it reached temp. The boiler only got up to 7.2 oz. so, under normal circumstances the pressuretrol does not cut-out but I'd feel much more comfortable if I knew it would cut-out at around 1.5psi when I need to turn the heat in the house up a few degrees. Should I consider a Vaporstat and if so, do you recommend the 0-4PSI model or the 0-16 oz. model. I saw somewhere on this site that the 0-4lb. model was better for a single pipe steam system. It also said to set it the Main at 1.5 and the differential at 1 but I noticed you recommend only a 2 oz difference between Main and Differential. Thanks for your help!
  • Fred
    Fred Member Posts: 8,541
    Recommendation on Vaporstat

    Can someone offer up a recommendation on if I should use a 0-16 oz. or a 0-4lb vaporstat on my single pipe steam system. Burnham boiler rated at 866 sq. ft. of steam 15 radiators, currently running at around 7.2 oz pressure during a normal cycle but pressuretrol lets the pressure get up to 3lbs, before cut-out when the boiler runs for extended period (raising the room temp 2 or 3 degrees) even though it is set at .05lb and 1 differential. Syphon is clean and clear.
  • Boiler Talk
    Boiler Talk Member Posts: 136
    edited February 2014
    How to adjust the PTrol Micro switch.

    See those screws on the micro switch inside of the Ptrol.   Turn off the power to the boiler.   Loosen them screws and then push the switch down and then retighten the screws.  Turn on power.  This is what I did and I don't have pressure above 18 ounces.  These units are not made to demanding specs. 
  • Fred
    Fred Member Posts: 8,541
    I'll give that a try!

    I will give that a try and see what happens! Thanks for the info.
    EBEBRATT-Ed Member Posts: 13,443
    Pressure control

    I wouldn't recommend screwing around with a pressure control put on the 4 lb vapor stat. Keep the PA404A as a back up safety limit.

    You shouldn't be screwing around with a limit control, that's a safety control. If you cant adjust it to control as you want (and you wont be able to with a PA404A) Replace it or keep it as a limit.
  • Fred
    Fred Member Posts: 8,541
    edited February 2014
    I did figure out how toCalibrate a Pressuretrol

    I don't know if anyone else is interested in calibrating their Honeywell Pressuretrol but after tinkering with mine, I finally figured it out!

    Inside the Pressuretrol, right below the micro switch, there is a pivot arm. At the end of that arm you will see a screw pin that is activated by the diaphragm at the bottom of the Pressuretrol. If you look very carefully at that screw pin, you will see it actually has a tiny (I mean tiny) hex head on it. It takes a .050 hex wrench and you can turn it clockwise (Towards the bottom of the Pressuretrol to decrease the Cut-out pressure or counter clockwise to increase the cut-out pressure (which none of us want to do but who knows, your Pressuretrol may be really screwed up!). Turn the power to the unit off first. You may find the first attempt to turn that screw a little bit stubborn (relatively speaking) because it has some Locktite on it but it does turn. Don't turn to much, a fraction of a turn goes a long way towards getting it adjusted where you want it (not even an eighth  turn). You may need to play with it to get it exactly where you want cut out to be but at least mine won't run pressure up to 3 Lbs when I have it set to cut-out at 1.5.
  • SWEI
    SWEI Member Posts: 7,356
    Assuming your description is accurate,

    it appears that Honeywell has a serious QC problem (as opposed to an actual design defect.)  This could be a good thing.