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Leaking Gas Hot Water Heater

cubicacres Member Posts: 360
edited December 2017 in Domestic Hot Water
We have two 40 gallon atmospheric gas hot water heaters in our 5 unit apartment building. One was replaced in July, the other is 5 years old.

Our tennents complained they had little/no hot water yesterday, so we went over to check it out and saw several gallons of water on the floor last night. We shut off the gas & water supply valves to let it dry out overnight, then tried it today.

It was able to start up ok with the spark ignition to light the pilot and ran for 5-10 minutes before we noticed the water leaking from the top center shaft area just below the vent hood & dripping down the side of the vent hood onto the top of the water heater before it went down the sides onto the floor about a gallon per minute or two. It looks like small a sputtering old faithful at the top center, running down the side onto the basement floor.

Does this suggest water leaked inside and filled the burner area, putting out the pilot eventually, stopping the water from heating? Or something else causing the small geyser-like sputtering at the top of the center shaft at the top of the heater, just below the vent exhaust hood leading up to the chimney?


  • Steamhead
    Steamhead Member Posts: 16,893
    edited December 2017
    Check the incoming water pressure when the heaters are cold and continue watching as they heat up. If the pressure rises substantially, there's probably a backflow device in the line, and you'll need to install an expansion tank to absorb the pressure increase so your new tank won't suffer the same fate.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • cubicacres
    cubicacres Member Posts: 360
    Thanks-are there reccomended gauges to add before the water heaters or further up the line closer to the main supply to check the pressure changes?

    We don't have any expansion tanks for the two 40 gal. hot water heaters connected in parallel to serve the building & I didn't see a backflow device other than on the boiler water supply, basement utility sink, and 2 outside garden hose hookups.

    Since connected in parallel, could we get by with a shared expansion tank between them, or it is better to have one for each water heater?
  • Ironman
    Ironman Member Posts: 7,379
    I'd put a tank on each one in case one had to be valved off and shut down. It's not a good practice on closed hydronic systems, but we're not dealing with that here.

    You also should look at your incoming water pressure. If it gets over 70 psi at night, you should install a pressure reducing valve.

    Municipal water pressure will get above 125 psi late night around here.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,335
    Hello, By " top center shaft area just below the vent hood", it sounds like the leak is from the weld at flue and top head of the tank. If so, the heater has failed, but a photo would be most helpful. Do you soften the water? That can cause an early death for tanks as the anode rod in the heater gets used up much faster with softened water.

    Yours, Larry
  • cubicacres
    cubicacres Member Posts: 360
    We just replaced it today, and don't use any water softeners. Surprising the old one was taken by a scrapper who pulled up in his van less than 5 minutes after laying it out on the curb!
    EBEBRATT-Ed Member Posts: 15,620
    Get a 0-100 psi pressure gage and a fitting to adapt it to a female garden hose thread. Then you can attach the gage to the water heater drain valve to check the water pressure
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    That’s really high pressure for municipal. I
    D look into a regulator and expansion tank. 50-70psi is plenty for residential unless you have a sprinkler system.
  • cubicacres
    cubicacres Member Posts: 360
    I just got a Raingauge brand $9 psi gauge and put it on the basement utility sink. It showed around 45 psi. Does that suggest average pressure, or any adaptations with the hot water heater or boiler?