Hot water heater hissing, cant find leak - but doubled water bill!

Old 06-04-12, 09:17 AM
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Hot water heater hissing, cant find leak - but doubled water bill!

I am having a huge problem with my water heater. It has made a hissing sound for about a month. It is constant. I recieved my water bill and electric bills and they have gone through the roof. The water company says I have a leak. I can not find any signs of one. The only thing I can think of is it has to be the water heater. Today I shut off the power to the water heater and then it continued to make the sound. SO I shut off the water. Someone please tell me what to do. I am a mother to 5 children and my husband is deployed.
Old 06-04-12, 09:23 AM
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Welcome to the forums and thank you for the service your husband and family do for us!

Can you inspect all the way around the heater? If there is a leak you should be able to tell. The hissing might not stop until the water has cooled down or the water pressure has reduced.
Old 06-04-12, 09:43 AM
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Sounds like a typical slab leak from what you describe.

Its the water piping that is under the cement floor. Most likely a hot water line near the water heater. The sound often resonates through the heater.

With no water running in the home, take a look at your water meter. Is it still spinning?

Your best temporary fix is to shut the heater water valve off. This will at least give you cold water in the home. Also shut the electric to the heater off.

Let us know.

Mike NJ
Old 06-04-12, 09:45 AM
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The most likely cause is a defective Temperature and Pressure (T&P) safety valve. It looks like this and is typically on the side of the heater near the top but could be in the top itself. If you have an add-on insulation blanket it might be under the blanket.

(Image courtesy of home repair,

The pipe shown going down from the valve outlet often goes outside the home or perhaps just into a crawl space. This valve protects from excessive pressure AND from excessive temperature. The pressure function could actuate as a result of a failure of a Pressure Reducing Valve (PRV) on your incoming water line and the temperature function could actuate due to a failure of the thermostat in/on the water heater. Or, sometimes the valve just plain fails.

CAREFULLY touch the pipe coming out of the T&P valve some distance away from the valve to determine if it is hot. If it is, this is the primary problem.

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Old 06-10-12, 06:20 PM
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are all your hot water pipes above the floor in the basement none going under concrete and such.the hot water heater is basically the cold water pressure feeding it.if you have no water leaking in the walls typically 60PSI from the town cold and hot.with no hot water running into sinks shower do you feel any real hot pipes reaching up in the basement area of the HWH feeding up into the sinks bath something is moving the water and making the heater heat the water

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