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john wood water heater gurgling sounds backflow problem help?????

heatmiser Member Posts: 16
was servicing a new customers home today. they had concerns on a john wood oil fired hot water heater. when it runs and heats the water it has a gurgling,rushing noise very similar to an air bound boiler system. the cold water supply pipe felt hotter than the hot water out pipe.  upon looking at the piping arrangement i noticed that there was no vacuum relief valve installed on the heater . this heater is not on street pressure its running approx. 50 lbs of pressure at a pressurized  well tank its a stand alone heater, its not hooked to a boiler with a pump etc.  would it help to raise the tank pressure and install a vacuum relief valve such as a watts n-36 . does it also need some sort of check valve or would a vacuum relief valve prevent the siphoning. any help will be appreciated.  


  • icesailor
    icesailor Member Posts: 7,265

    The noise you hear is from sediment in the bottom of the tank. It makes boiling sounds because it stops the free transfer of heat into the water. Water boils between the sediment. You need to flust the water heater. You need to turn off the cold water supply and drain the water heater through the bottom drain. When the tank is completely drained, turn on the cold water inlet with the hose on the drain, open and draining. The idea isn't to fill the tank but to flush the crud in the bottom. It doesn't take too much to make it happen. And my experience is that it still may happen. I find that the water heaters don't last much lomger once it starts happening seriously.
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