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Calcium in my hot water heater

how to desolve calcium in a electric hot water heater i am replacing element, and want to get calcium out.

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Try dissolving with a gentle acid like white or apple cider vinegar - these are very inexpensive by the gallon.  If your drain is too slow you can use a wet/dry vac with a 3/4 inch hose.  Remember that this is your water supply so you should not use any chemicals unless you are 100% positive that it can not harm you in the short or long term. 

Many/most people don't bother replacing the element and just deal with water heaters by draining off any sediment periodically and replacing them in their entirety once the element burns out (after 7 - 10 years).

In most water supplies calcium, magnesium and iron along with other minerals are dissolved in the water.  All of these will deposit in a heater.  Calcium usually comprises the greatest percentage.  As water is heated calcium becomes less soluble (it wants to deposit).  Since the heating element is the hottest surface in the heater the deposits will form there first.  As the deposits get thicker the heating element has less ability to transfer its heat into the water.  At some point, failure of the element is expected because it gets too hot for too long of a period.  Also, as the deposits increase the heater works longer, this results in greater electrical bills? 

These metal ions (calcium, magnesium and iron) will form deposits in the heater usually combined with carbonate.  To remove the deposits the carbonate/metal bond needs to be reversed.  To solubilize the deposits the pH of the solution around the deposit needs to be lowered to less than 4.0.  At 4.0 and above the deposit will not go back into solution and you will not be able to remove the deposits.  For your reference a neutral pH is 7.0.  For your application you can use vinegar.  It is a mild acid that is OK to be consumed by humans.  Other acids like phosphoric (Lime Away), hydrochloric or sulfuric (battery acid) are much stronger and you have to be much more careful.  The lower you go below a pH of 4.0 will dissolve the deposits faster.  A ph of 2.0 is 10 times stronger than 3.0 and 100 times stronger than 4.0.  You can dissolve the deposits by pouring in vinegar but it is best if you can circulate the vinegar solution through the heater in a loop.  As deposits are dissolved the pH of the vinegar solution will rise requiring you to replace it with new vinegar.  If you can check the pH (litmus paper or other means) of the solution (circulating or not) you will know when to replace it.  If the pH no longer rises you have dissolved all that is possible to dissolve, keeping in mind that the pH will stop rising at 4.0 even if more needs to be dissolved.

Low pH solutions are corrosive to mild steel and copper.  If you do try to dissolve the deposits do not leave the low pH solution in the heater for extended periods of time after you have completed the clean up.

You can eliminate this issue by removing the calcium, magnesium and iron before it ever gets to the heater by softening the water.  There are many water softeners on the market.  No matter how they are designed or how expensive they are their purpose is to replace hardness ions with a soft ion.  Sodium (often supplied in the form of rock salt or pellets) is a soft ion and it is used to regenerate softeners.  Soft ions will not form the deposits.

Good luck.


the softern is the only way to solve this issue

but make sure when you get the softener you have to keep the salt solution tank full for regenerating the resin in the softener



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