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Tim Question for 1968 diaphragm gas valve......

JUGHNE Member Posts: 11,108
Have this valve on a 2,000,000 BTUH atmospheric burner on a coal conversion Kewanee steel fire tube boiler.

Boiler is rated at 1,080,000 input.

2 1/2" General Controls 3950X valve body. Has large (14"?) "pancake" diaphragm on top of it with push rod for air damper with lever with counter weights on it.
Has electric pilot valve mounted on pancake with tube connected to the bottom section of pancake.

Is is operable but a little "gasey" at the plunger rod and around where the operating solenoid valve is mounted.
Probably has been a minor leaker for awhile.
Any advice about repairs or replacement.
The air damper could be locked in place as needed.
The operation is slow opening gas valve.
Even the theory of operation would be helpful.

Thank you


    JUGHNE Member Posts: 11,108

    EBEBRATT-Ed Member Posts: 15,839
    Not Tim but I'll put my 2 cents in.

    I would replace it with a Honeywell motorized gas valve. You get the valve body separate from the actuator. The actuators are made with various opening times and have a square shaft that you can put a crank arm on to drive the damper. They are $$

    Some states some codes would require a second valve piped in series on a burner that large. The second valve can be a solenoid

    They still make diaphragm gas valves but I don't know about one with an air damper hook up. Pipe size? 1 1/2? .....2"
    JUGHNE Member Posts: 11,108
    Thanks Ed,
    The pipe size on the existing is 2 1/2".
    Could most likely be smaller as we need only 1/2 the burner input now.
    Could just get the air damper set for good combustion and lock in place.

    Every year there is talk of changing out the boiler.
    It might limp along another year.
  • retiredguy
    retiredguy Member Posts: 930
    Wow, I have seen a million of these dinosaurs. The best money spent would be on a completely new boiler or at least a new burner and draft controls. In Pennsylvania, when that center shaft of the gas valve leaked the boiler inspector would force the customer to replace that gas valve.

    Geeze, that boiler looks like some of the crap I worked on. I bet it has a "flame rod flame sensor" on a conversion burner on an NRC boiler. Those type burners were known to provide very little in boiler or burner efficiency. Operating costs including fuel usage are usually very high.