Pro Handyman Blog

Water Heater Rumbling Noise

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A customer just called and asked about why her water heater was making a thumping noise. Specifically, she said the sound was similar to the noise that her clothes dryer makes when she has a pair of tennis shoes rolling around inside.

I asked her when the last time she drained her water heater, and she didn't know. The water heater was 5 years old. It sounded to me like it had never been touched since it was installed. What happens is that you get a layer of sediment at the base of the water heater. If your water heater is gas, this sediment effectively creates a barrier and slows the transfer of heat from the burner to the water, making the unit burn longer to heat your water (and also costing you more money). This sediment makes your water heater inefficient and causes it to make a gurgle or rumbling sound. If your water heater is electric, the sediment builds up on the heating elements and eventually flakes off.

All of this sediment collects on the bottom of the water heater's tank and effectively displaces the amount of water available turning a 40 gallon tank, for example, into a 38 gallon tank.

This customer's water heater was gas and the analogy I used was for her to imagine cooking spaghetti sauce. Imagine a delicious thick sauce on the stove. As the heat builds up from the burner below, the sauce is so thick and heavy it can't boil and instead develops a large bubble that finally burps out. This is what happens at the bottom of your gas water heater, but instead of sauce its sediment. Here is some information on flushing your water heater.