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again gas valve

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billy89
billy89 Member Posts: 2
in Gas Heating
can i replace vr8200c3005 with a vr8200a2132 they have all the same specs

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  • Tim McElwain
    Tim McElwain Member Posts: 4,621
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    No the VR8200C is a step opening valve and the VR98200A is a standard opening.
    kcopp
  • Motorapido
    Motorapido Member Posts: 307
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    Tim McElwain said:

    No the VR8200C is a step opening valve and the VR98200A is a standard opening.

    Tim, not to take this thread off topic, but I need clarification on "step opening" versus "standard opening." I'm guessing step opening opens the valve to less than full-flow and then after a short delay turns on full gas flow. My gas valve sounds like it does this and I can see flame difference and sound difference between the initial firing and then the louder sound of full flow. I've always wondered -- on my grossly oversized boiler -- if it is possible to modify the control input so that the valve stays on the initial, lower-flow setting to essentially down-fire the boiler. I'm guessing that the initial, partial opening might not create the ideally balanced flame and might not create enough heat for good chimney draft and might cause condensation. But anyway, can you explain further the two types of valves? Did "step opening" replace "standard opening" as an enhancement, or are both type still installed at the factory?
  • mattmia2
    mattmia2 Member Posts: 9,637
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    It is built in to the valve, there is no external control of the slow opening process. It opens slowly or in stages to let the flame propagate to all sections of the burner before it supplies it with the full flow of gas. In burners where the flame is slow to propagate you can get delayed ignition where some parts of the burner will light with a small explosion if you start with the full flow. This isnt designed to down fire the appliance.
  • Tim McElwain
    Tim McElwain Member Posts: 4,621
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    All the major manufacturers Honeywell, White Rodgers and Robertshaw all offer several different opening characteristics. With Honeywell as the standard the letter following the valve number "A" is standard opening "C" is Step Opening Comes on on low fire and 10 seconds later goes to full input. Then there is Two Stage which can come on low fire satisfy the thermostat and never go to hi-fire. This is accomplished by having a two stage thermostat. Normal thermostat operation is "R" and "W" two stage will have R - W1 and W2.
  • Tim McElwain
    Tim McElwain Member Posts: 4,621
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    Thisis one of the best explanations I have seen:

    Standard open valve

    • Fast open
    • Reaches full rate in 1 to 2 seconds depending on capacity
    • On some applications, particularly low firing rates there is little variation in regulation for a half second when it first turns on

    Slow open valve

    • Takes about 4 to 5 seconds to get fully open
    • Under maximum capacity it may even take 9 to 10 seconds to get fully open
    • Again, for service replace with slow open

    Step open

    • Valve opens to some fixed (non-adjustable) low rate for light-off and after 10 seconds goes to full rate
    • For service work replace with step opening only as there may be ignition problems with any other opening characteristic
    • Equipment manufacturers chose step open (at higher cost) for a reason
    • Usually used to make light-off smoother or to cure light-off problems

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