OT: Hot water heater issue-thumping

redtom · Dec 25, 2012

A new thing going on. My 40 gal nat gas heater is "thumping". Its about ten yrs old. It occurs after a shower while its warming back up. It does a few solid thumps a few minutes apart maybe 6 times. We are on city water which is nice a soft. I never had an issue with an anode rod. Water isn't stinky or anything. It just started maybe a month ago.

OH Boy · Dec 25, 2012

It has sediment in the bottom of the tank, flush it out, if you can.

VicS · Dec 25, 2012

No matter, it has built up crap in the bottom. Shut off the water and drain it. Always helped ours. Do you have a softiner? our city water needs one. Haven't had any drip marks on the tub since we got one. Also no thumping! Vic

Gary from Muleshoe · Dec 25, 2012

It is the sediment in the bottom of the tank. When water heats it causes it to bubble and the sediment is causing it to be larger than normal bubble hence the thumping sound. On electric heater you can take out the bottom element and clean it our using a shop vac. Commercial gas heaters have an access panel that is for cleaning them out. Might look but I doubt your 40 gallon household heater has an access panel.

37chief · Dec 25, 2012

Here is another thaught. Normal operation water goes in at the bottom, from a tube connected at the top. It is called the dip tube. If this tube falls off at the top cold water mixes with the hot at the top, which causes this rumbling noise. More than likely this is the problem. It is possible to add a length of pipe, and make it go to the bottom again.Stan

Dalet · Dec 25, 2012

My hypothesis is that it is caused by the new cold water entering the system. This water has air entrained in it due to the cold temperature. When it gets near boiling the air is released. Eventually you have some bubbles that need to be released.

FBH44 · Dec 26, 2012

Pick a day when you can give it all 10 - 12 hours, get a shop-vac, get a troubloe light, then unscrew the bottom element, if you can.... you"ll see the probolem.

Dean Olson · Dec 26, 2012

If that heater is in a place where it will do damage when it leaks I recommend replacing it. Modern heaters just flat do not last as long. Back in the day water heater where heavier than they are now. Less metal thinner tanks. It's either that or I'm getting stronger as I age

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There is a layer of sediment on the bottom. The water in that layer is boiling as the transfer of heat is slower.

Chip812 · Dec 26, 2012

You need one of these: http://www.lowes.com/pd_160680-4832...currentURL=?Ntt=expansion+tank&facetInfo= plumbed into your pipe near the water heater...

Blackhole49 · Dec 26, 2012

Bottom element on natural gas?

OT: Hot water heater issue-thumping

redtom

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OH Boy

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VicS

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Gary from Muleshoe

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37chief

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Dalet

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FBH44

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Dean Olson

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Chip812

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Blackhole49

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