How to get rid of crystals in hot water heater?

[H.Huester]

Have the hot water heater out and flushed it with a garden hose. Out came quite a bit of white crystal-like flakes - I presume it's some sort of mineral build-up (calcium, lime...). I looked into the hot water line and it has a build-up as well. What can I use to flush out the remaining build-up? Thanks in advance.

[Ganglin]

Heated white vinegar will do it - finding a way to fill the lines and tank is another issue....

[Jammer]

It's calcium carbonate with a little magnesium thrown in.

It can be removed with an acid solution of any kind. As Ganglin notes, vinegar will work, though you have to use a good deal of it. Other acid cleaner products, like San-teen and hydrochloric acid, or sulfuric acid (sold as battery electrolyte at the napa) will work more quickly and require less chemical, but require considerable precautions while handling. Minimally, rubber boots, rubber apron, rubber gloves, splash resistant goggles, and a face shield.

The hazard is that, in addition to being corrosive, the acid will react with the white residue to produce a gas, which will pressurize the water heater, and potentially blow acid out through whatever pipes are open under pressure.

Look up "heat exchanger chemical descaling" on google for more.

The stuff does lead to lower efficiency and early failure due to hot spots, since the steel under the calcium deposit is heated to higher temperatures than it would be if it were in direct contact with the water. It also makes the water heater noisy.

Usually the safest way to do this with a water heater is to drain it, leaving 1/2" or so of water in the bottom, then remove the relief valve and (while wearing proper protective gear) slowly add in the acid through a small (1/4" or so) piece of tubing inserted through the relief valve tapping. Any gas produced can exit through the open space between the tubing and the threads of the relief valve tapping. Then drain and rinse. The worst deposits are usually on the bottom, so get those first, then you can fill the water heater most of the way and add some acid. The solution that results, while dilute, will still work and with time will get most of the stuff on the walls and burner tube.

[BillTex]

Vinegar...or CLR.

[bobfowler]

Originally Posted by H. Huester

Have the hot water heater out and flushed it with a garden hose. Out came quite a bit of white crystal-like flakes - I presume it's some sort of mineral build-up (calcium, lime...). I looked into the hot water line and it has a build-up as well. What can I use to flush out the remaining build-up? Thanks in advance.

I had a heck of a time getting the crud you describe out of my water heater. The first time we fired it up, the flakes came down the line and clogged the aerators at every faucet so NOTHING came through. The first thing I tried was one of those plastic wands that attaches to a garden hose. It blasted some of it out, but not all. When I had the water heater out to repair the floor under the furnace area, I spent an hour or so getting ALL the crud out (I hope).

[87MH]

Originally Posted by H. Huester

Have the hot water heater out and flushed it with a garden hose. Out came quite a bit of white crystal-like flakes - I presume it's some sort of mineral build-up (calcium, lime...). I looked into the hot water line and it has a build-up as well. What can I use to flush out the remaining build-up?

Lets look at a few facts -

• You're dealing with a 35+ year old gas appliance.
• An Acid Flush is never 100% effective - you will always fighting nozzle plugging.
• You already have the water heater removed.

Hands down, the best course of action for you is a new water heater.

Old gas water heating systems usually mean corroded burners and air mixers. Pilot lights are subject to failing due to internal oxidation. The thermal safety "burner on" element is always subject to fail. The gaskets in the thermostat/pressure regulator may have deteriorated in the last third of a century.

Drain the WH, lift it and get a good "feel" for how much it weighs, go to a local Camping Supply Store and heft a new replacement - you'll be amazed what the weight difference - consider the time to clean out and refurb your old unit.

Natural Gas Liquids (LPG's), open flames, and Airstreams do not combine well. Some things it's cost effective and safe to refurbish - gas water heaters are not in among them.