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

Duel safety gas Valves

John G. Merritt
John G. Merritt Member Posts: 140
in THE MAIN WALL
Guys:

What is a duel safety Gas Valve, and how is it different from a standard Gas Valve?

John

Comments

  • Unknown
    Unknown
    Redundant Gas Valves

    Prior to 1979 the requirement for gas valves was that they have one valve seat. This was called the main valve seat. If it was a 24 volt standing pilot system it would have your regular pilot safety and then the main valve seat.

    Due to the one seat sometimes sticking open and causing a run away valve (it would not shut off) and hopefully the relief system would work. On warm air this is no relief system so look out. The high limits were out of the picture as this was a mechanical failure.

    The ANSI standard for gas valves was changes in 1979 to require either two valves in gas controls for central heating or at that time they also would allow an Energy Cut Off wired into the millivolt circuit of the pilot safety to act as a back up safety in the event of mechanical failure. All gas water heaters still have ECO's built in to accomplish this.

    The gas valves today if 24 volt standing pilot have in addition to the pilot safety two internal valves in series with the gas flow. They are playing the odds that two valves are less likely to both stick open than just one. When you get into intermittent pilot system (spark ignition) the first valve is called PV (pilot valve) the second valve is called MV (main valve). For all Direct Burner Ignition - Direct Spark or Hot Surface Ignition the two valves open together the gas then is ignited by spark (DSI) or igniter (HSI).

    Honeywell identifies their gas valves that are dual seated by the "R" in the valve # such as VR-8300.

    Robertshaws valves that are redundant are their 7200 series. The 700 series is not redundant watch out for that when replacing gas valves. The rule is you can replace a single seated with a dual seated, but you can not replace a dual seated with a single seated.

    White Rodgers 36 E series are all redundant.

    Hope this helps. By the way we cover all this and much more in our seminars. With out training you really do not know.
This discussion has been closed.

Categories