Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Need Modulating Vaporstat

Is there such a thing?  Just upgraded a Smith 19A-6 with a new Powerflame CR1-G-12.

The problem:  the system runs on 6 ounces and I learned the pressuretrol that controls the modulation doesn't go low enough to function.  As a result, I can't modulate the burner.

Does anyone know of a control with a 120 ohm potentiometer that will allow me to modulate a low pressure system like this?

Steve Garson

Boston, MA
Steve from Newton, MA


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,515
    below 6 oz.

    can you replace the pressuretrol with a vaporstat. i think some of these modulating systems use 2 vaporstats-one to handle the transition from high flame to low, and the 2nd to cut the burner off completely if the pressure continues to rise even on low fire.

    the 0-16 oz honeywell vaporstats would be right for you. --nbc
  • The Steam Whisperer (Formerly Boilerpro)
    edited August 2011
    Available.... YES....But

    you have to combine a few components.  If you start with an electronic modulating pressure control that accepts a typical 4-20 MA pressure sensor signal, you can simply swap in a pressure sensor that operates in a lower range.  The lowest most controls some with is 0 to 30 psi, however, you can get sensors that operate at much lower ranges,  say 0 to 15 ounces.   The display will not be correct , but operation is uneffected.  You would then just need to set up the operating range off  a reliable vapor gage.  Omega, ashcroft and others have pressure transducers.
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert

    Noisy Radiators are a Cry for Help
This discussion has been closed.