Water heater noise

Lately I have been noticing a thumping noise from my water heater. That’s the best way I can describe it. Not consistent, just hear it thump from time to time. No water will be running and the burner is not ignited when it happens. It’s a natural gas heater, 40 gallon, tall. Tried draining it, flushing it but that didn’t help. Is it possible to have an airlock in the top?

It’s probably telling you to get a new one!

Possible sediment build up at bottom of tank. The noise is actually bubbles that escape through the sediment.

Exactly it is hard water build up in Bottom of Tank and the small amont of water under the scale turns to super heated water and then when it escapes it flashes to steam and that causes the thunder thumping noise you hear.
Sorry If you had drained the tank bottom frequently it might not be so bad ,
What is the age of the Tank and are you in a hard water area .
A water softener might be a good investment when you replace the tank
Roy Cooke

Periodic removal of the sediment in the tank by opening the heater drain vlave until it runs clears can prolong :)life in areas with hard water.

Located in Columbia SC. Water is city water and I don’t think I have a hard water problem. Never had it tested either, though. Water heater is about 10 years old. Pulled the anode to check it a while back and it was pretty crusty. Been having some problems with soot on the burner also but after cleaning it twice in 2 weeks it hasn’t happened again. Thinking it may have been something in the gas?? Probably is time for another one. Just hate to get it now. Any suggestions on a good one? Mine is a State industries.

10 years isn’t bad but I would still open the drain and run it until its clear. This may dislodge any sediment that is still loose. If you decide to buy a new one, pay attention to the energy sticker on the unit and compare. Tanks can be purchased with 5,7, or 10 year warranty’s for example. Also keep in mind the the new heater will probably not fit exactly the same and will require some plumbing changes for the water and gas connections. Consult a plumber if you are not familiar with installing this type of appliance.

Check out http://www.bradfordwhite.com/ They have a helpful site for sizing properly, etc.

Noises like this, also refered to as ‘popcorn sounds’ are an early indication that the water heater is going to fail, near term. The cause is sediment build-up in the bottom of the tank that deteriorates the cermaic liner.

Make sure that the water heater is in a pan (to minimize water damage when it lets go) and start budgeting for a new one.

Drainage of the water heater, to drain off sediment at the bottom, is recommended twice or three times a year.

Sounds like you are going to have a near term failure. Water heaters ony have about a 10 year life in any case.


Thanks for the replies. I was reading on another site a while back. A guy was telling how to get up to 10-15 years out of a water heater by careful maintanence. Flushing the tank a couple times a year, keeping a good anode in it and replacing the diptube with a modified one, ie. bent on the end up to around 90 degrees. That supposibly helps keep the sediment from building up. Oh well, too little too late for me. But I’m better educated now though. Thanks again.

Glad to be of help.

Call me if you have any questions.