RenzoARG t1_jcuwlg6 wrote on March 19, 2023 at 7:16 PM

If it's electric, you need to replace the resistance that heats up the water. Otherwise, all you need to do is remove the plaque buildup by filling the heater pipes with either vinegar or hydrochloric acid and purging it after an hour or so after it did its chemistry. Repeat with clean water 2 or 3 times to remove any traces of acids (tho it is not dangerous, it does sting in your eyes a bit if you shower with those residues).

incensenonsense t1_jcv3jr1 wrote on March 19, 2023 at 8:02 PM

I recommend sticking with vinegar and skipping the hydrochloric unless you have some product specifically diluted for water heaters or are a pro with extensive knowledge on use and safety procedures. The muratic/hydrochloric acid sold for pools is so concentrated that it’s downright dangerous. Need to wear acid gloves, goggles, and be really careful. In an OSHA approved setting pretty sure it would require gown, face shield, and ventilation. Putting in too much would also corrode through the metal inside the water heater very quickly, and if any got in your eyes you could become blind and on skin you would get chemical burns.

Vinegar or citric acid (or even glycolic acid which is in Zepps descaler) are weaker acids and are effective at dissolving minerals but gentle enough on the water heater internals so really good for this application. Still be careful not to get any in your eyes.