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has anyone ever seen a gas valve fail open?

luketheplumber
luketheplumber Member Posts: 123
I have heard a lot about it happening on water heaters and them going through the roof like on the mythbusters show. But has anyone here ever see a gas valve fail in the open position on any appliance, if so whats the story?
Learning about Steam and Hot Water Heating Systems. Will Soon be looking for an apprenticeship in Steam Heating as soon as I Graduate.

Comments

  • luketheplumber
    luketheplumber Member Posts: 123
    shoot! how do i move this discussion to the main wall
    can I do it of do i need an administrator to do it?
    Learning about Steam and Hot Water Heating Systems. Will Soon be looking for an apprenticeship in Steam Heating as soon as I Graduate.
  • Fred
    Fred Member Posts: 8,515
    edited April 2020

    shoot! how do i move this discussion to the main wall
    can I do it of do i need an administrator to do it?

    Ask @Erin Holohan Haskell to move it for you. I had a water heater thermostat fail and the water was probably boiling. I heard the water pipes rattle and I though I had an animal running across the pipes in the basement. When I found none, I turned the hot water faucet on, in the basement, it was a steam cloud. Shut the water heater down immediately! PRV hadn't blown yet.
    luketheplumber
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,312
    Seen a few on boilers.
  • luketheplumber
    luketheplumber Member Posts: 123
    edited April 2020
    > @Erin Holohan Haskell can you help move this?
    my mistake
    Learning about Steam and Hot Water Heating Systems. Will Soon be looking for an apprenticeship in Steam Heating as soon as I Graduate.
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,084
    Hi, It’s extremely rare for gas valves to fail open but good plumbing has a lot to do with it. Propane water heaters have a sediment trap built into the gas valve so flakes of rust or other debris cannot get caught in the valve seat. Other gas appliances have a dirt leg the plumber builds. Most plumbers are careful not to use Teflon too close to the ends of threaded pipe, so no fragments of Teflon wind up in the valve. Still, with tank type water heaters, the relief valve is really important. I’ve serviced thousands of heaters and in my area one of forty relief valves is plugged solid. It’s important to test them.

    Yours, Larry
    Big Ed_4
  • retiredguy
    retiredguy Member Posts: 353
    I witnessed an older Maxon 3" or 4"motorized gas valve stick open due to a broken bearing on the gas valve release closing mechanism. Nothing happened since there was a second blocking gas valve that was usually required on larger installations. I have seen a few oil valves stick open with disastrous results. In one case, on a brand new H B Smith 4500W boiler installation in a high school, the shock was felt in the whole building and the new boiler was a total loss.
  • SuperTech
    SuperTech Member Posts: 1,579
    I've never seen it happen. Usually if something fails it's the solenoid burning out and keeping the gas valve closed. Any appliance should have redundant safety's to prevent what was shown on mythbusters. I did have an electric water heater split open like someone dropped a M-80 in it at my house. I've since moved on to using an indirect tank. I've definitely seen plugged relief valves on the job. Testing them should be done annually, but its not because so many would need replacement because they would drip afterwards.
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 1,558

    > @Erin Holohan Haskell can you help move this?
    my mistake

    Yes, I've moved it.
    President
    HeatingHelp.com
    luketheplumber
  • JUGHNE
    JUGHNE Member Posts: 8,175
    A memorable gas valve stuck open was an old furnace from the 50's.
    The older tenant lady was getting panicky as here house got over 80 degrees. She shut off the power to the furnace which stopped the blower. (this blower was controlled by the old school heat sensitive plenum switch).
    That caused the oversized furnace to really overheat.
    There was cheap flex duct connected right to the plenum on top of the furnace and it was getting pretty soft.
    Fortunately no fire damage.

    Large gas trains may have 2 gas valves in series for redundancy.
    Many of those have a vent pipe in between the valves with a solenoid controlled valve that is piped outside.

    There are plenty of piping diagrams available for Honeywell gas trains for larger equipment.
  • rick in Alaska
    rick in Alaska Member Posts: 1,160
    Just an fyi. If you are getting steam out of your faucet, leave the water running, and then turn off the heater. That way the incoming cold water into the tank will help cool it off, and hopefully prevent an explosion.
    Rick
    luketheplumberkcopp
  • Fred
    Fred Member Posts: 8,515

    Just an fyi. If you are getting steam out of your faucet, leave the water running, and then turn off the heater. That way the incoming cold water into the tank will help cool it off, and hopefully prevent an explosion.
    Rick

    Thanks Rick, That's exactly what I did!

  • jumper
    jumper Member Posts: 1,593
    Interesting that gas doesn't have failsafe like a fuse for electricity.
  • JUGHNE
    JUGHNE Member Posts: 8,175
    Commercial range hood fire suppression systems have a spring loaded cable system. Fuse links are in the potential hot zones and if melted open the pressurized system is energized.
    Also there can be a spring loaded normally closed gas valve that is held open by the same cable system.
    If the suppression system is set off then the gas valve snaps shut.
    It is in the main gas line that feeds all of the under hood appliances.

    Also a normally open master relay(s) for the electric appliances that loses it's control voltage if system is set off.
    Solid_Fuel_Man
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,540
    Anything mechanical can fail. Gas valves are very reliable but and dirt or rust can keep it open
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 1,817
    edited April 2020
    Several-teen :/ years ago I received a call from a customer about a high gas bill in their unoccupied summer home. I picked up a key from the realty company and went to find the house was 92°F inside when the outdoor temperature was 17°F. I went to the thermostat and found it set for 55° and the indicated temperature was above 90°. went to the furnace room and found the burner and blower operating. When I turned off the switch the blower stopped but the burner did not.

    Shut off the manual gas cock, called the customer and got approval for a replacement gas valve. Since the furnace was probably overheated, I also completed a heat exchanger test to make sure there was no crack in the heat exchanger.
    That summer we replaced the heater and air conditioning system with high-efficiency equipment.
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
  • Big Ed_4
    Big Ed_4 Member Posts: 1,646
    I never seen it happen , me being a old oil guy ..But I can see it happen now , Thanks...
    I have enough experience to know , that I dont know it all
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,252
    I saw a gas valve leak by on a year old propane range. It was a dual valve one outlet (spud) for the oven bottom burner, and the other spud for the top oven ( broiler) burner. The bottom burner was held open just enough to smell.

    I replaced the valve assembly which included the appliance regulator. When I took is to the shop for failure analysis (I was curious!) I found a sliver of aluminum stuck between the soft seat and the bimetal strip. The entire valve was made of aluminum, so my conclusion was that it was leftover from the factory machining process. The manufacturer, GE, warranted it.

    Its suprising to me how little safety is built into appliances as compared to commercial redundant gas valves, each tested everytime the burner goes through its pre combustion tests.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • AMservices
    AMservices Member Posts: 593
    I had service call 6-7 years ago where a sprinkler head blew off in the middle of the night right next to a Moden heater in a auto body shop.
    Thankfully the sprinkler system did its job because it wasn't connected to the alarm system 🤦‍♂️.
    The guy opening the shop in the morning only knew there was a problem because there was water all over the floor under the Moden and the heat was off.

    First I find the power was off, so I found the breaker and re set power.
    Then I go up and the pilot was out so tried lighting the pilot... no gas.
    Maintenance man said he shut the gas off from the meter.
    So I'm sitting up on top of a 14' A frame ladder waiting for this guy to get back to tell me to try it, when I hear gas filling the heat exchanger.
    I had no idea where he was for me to even run to him and say shut it off and I was right there with my BBQ lighter for the pilot. So I Quickly lit the burner before the place filled with gas.
    Gas valve was stuck open.
    Definitely the closest I've been to blowing myself up.
    luketheplumber
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