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Old 05-16-2011, 04:21 PM   #1
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Water Heater Calcium Deposits -- What to do?

I have a 6-gallon Atwood water heater (model #G6A-8E) in a 1999 27-foot Safari which I purchased recently. It heats fine, but the water reservoir seems to be loaded with calcium deposits. When I flushed out antifreeze this spring with city water, then opened the water heater bypass, then opened all the faucets, every faucet (all of which operated properly when flushing the antifreeze) was now clogged shut with sand-like calcium deposits. I opened up the water heater drain and ran city water through the water heater for 45 minutes -- at the end I was still getting quite a few white flakes in the draining water. The previous owner had used one of those Hott Rods to heat the water electrically for about 6 years, and someone told me this may have contributed to the problem. I'll remove the Hott Rod -- any ideas on how to remove the calcium deposits? Should I consider replacing the water heater?
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Old 05-16-2011, 06:01 PM   #2
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You need to get about 3 gallons of white vinegar and get it into the water heater through the drain hole. You can use a 3/4 nipple and I used the hose from a old hand held shower head. Put a funnel on the hose and hold it higher than the WH to get the vinegar in and follow with 3 gal. of water. Close off the bypass valves and just let it sit for a few hours. You can fire up the heater to warm it up. Then just lower the hose and watch the white stuff come out.

You may need to pressurize and flush your system a few times and take all the filters off of the spigots and hope nothing plugs up the faucet valves.
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Old 05-16-2011, 08:36 PM   #3
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What Mojo said, except I would pull the pressure relief valve and leave the drain plug installed. Much easier to fill this way. I might use more vinegar and less water than a 50% mix too.
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Old 05-17-2011, 05:54 PM   #4
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Limited experience owner, but I had enough deposits to glog my faucets, my .02$, I didn't know about the vinegar approach.

I used a piece of 1/4" copper tubing and adapted it to a water hose, only needed a compression fitting+reducer+adaptor to the hose. The tubing was about a foot long or so, but I crimped the end almost shut to make a nozzle, bent it into a large J shape and inserted the spray tube in via the drain plug, hit the water and rinsed the inards of the tank. The crud came a flushing out. Over a year of mostly backyard camping and several outings later all faucets unclogged.
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Old 05-17-2011, 05:57 PM   #5
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The vinegar approach is the standard recommendation for build-up in coffee machines, so should work with the water heater as well. Put it in, heat it up, dump it out. Rinse.

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Old 05-18-2011, 02:02 PM   #6
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Thank you all for the great advice. I will try the vinegar approach first and hope for the best. These forums are certainly helpful!
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Old 05-18-2011, 02:11 PM   #7
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Vinegar works well, is cheap, and doesn't harm any of the components of your system.
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Old 05-18-2011, 03:11 PM   #8
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The deposits are mostly calcium carbonate but may also contain manganese compounds and other calcium salts depending on the nature of the water that caused the deposits.

You remove them by dissolving them with acid. White vinegar is typically 6% acetic acid. It works slowly and will not remove all the lime. There are other de-liming agents available that use higher concentrations of acid, or stronger acids like hydrochloric acid or phosphoric acid.

Any acid will also attack the steel in the tank and there is always some risk of de-liming causing leaks, both due to the chemicals attacking the steel and due to the possibility that pinhole leaks may exist that have been plugged by the accumulation of lime.

If the hott-rod was heating the water to unusually high temperatures that may have contributed to the problem but ultimately it's about the quality of the incoming water.
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