When it comes to performance, efficiency and longevity of tankless hot water heater we learn more every day that they need to have annual maintenance service performed by a qualified technicians, but seldom do we think of how important is the role of water quality going to these units.
Some water heating equipment manufacturers would even void the warranty the parts breakdown if caused by poor water quality. Hardness, rust & scale chlorine and abnormal PH levels are mostly seen to have been a cause for many service calls resulting in unexpected expenses and some frustration for most homeowners.
Some water heater manufacturers recommend descaling done with food grade vinegar every year as part of the maintenance to address this issue.
EPA (Environmental Protection Agency) has a table of allowed maximum contaminant levels in National Secondary Drinking Water Regulations (40 CFR Part 143.3). This can be helpful when testing local water quality and knowing what you are dealing with and widely used by a few water heater manufacturers.
Best practice would be to have the water tested by a lab and address the poor quality by prevention methods and filtration. Depending what you have in your water you can at least have an inexpensive scale inhibition water treatment filter installed on cold water inlet side of your water heater and easily replace the filter every six to 12 months depending on the contaminant levels of your water. This alone will save quite a bit of headache down the road and unexpected interruption of hot water and emergency service calls to plumbers.
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