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pressure

kamruz
kamruz Member Posts: 18
Hi,

I have 3 year old Well Mclean steam boiler with Honeywell  pressuretrol and 30 psi pressure gauge. Pressuretrol cut in set at 0.5 and inside dial set at 1. But when there is call for heat boiler turns on and when it reaches 3 psi it turns off, after 2 to 3 minutes it turns back on when the pressure falls to 2 psi. 

My question are:

1-Why is it going up to 3 psi before it turn off and turns back on at 2 psi, shouldn't it go up to only 1.5 psi, with the current pressuretrol setting? what should it do?

2- Is it normal to turn back on after 2-3 minutes and pressure falling 3 to 2 psi in that time?

Please help

Thanks



   

Comments

  • steamedchicago
    steamedchicago Member Posts: 72
    accuracy of gauges

    0-30 gauges tend to be inaccurate at the low end.  That's why fitting a 0-3 psi gauge is a common recommendation.  It's possible that either your pressurtrol is inaccurate, which is possible, or that the gauge is inaccurate at those pressures.  Or both, of course.



    You get pressure building in a system when the boiler makes steam faster than the system condenses it.  If it's cycling on pressure before the radiators are getting steam, you have inadequate main venting.  If it's cycling when the radiators are hot, there can be lots of things going on.  If it's trying to raise the temperature a large amount (coming back from a setback, or you raised the thermostat's setting), it may be expected.  If it's happening a lot in normal operation, it's quite possible the boiler is oversized.  
  • kamruz
    kamruz Member Posts: 18
    Pressure

    If I put 0-3 gauge and if pressure goes above 3 then what happens to the boiler or gauge?
  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    Over 3 psi...

    Nothing.  Most gauges -- and all boilers -- will withstand considerably higher pressures before things get interesting.  Gauges will typically go to at least twice the max.  Boilers are designed to be safe at more than 15 psi -- which is why the pressure relief valve is set at 15 psi, and all codes and most insurance require that 30 psi gauge.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • kamruz
    kamruz Member Posts: 18
    Gauge

    Hi,

    The gauge should be straight or angle?

    I have pigtail, straight gauge and pressuretrol on a T, is it correct?
  • kamruz
    kamruz Member Posts: 18
    Gauge

    Can I just replace the current 0-30 with 0-3 gauge or I have to keep current one on and add

    New one.
  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    You have to keep

    the 0 to 30.  It's a requirement of most codes and insurance policies. 
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England