This is an idea that 100% of Tankless water heater companies would advise you not to do. However, it can be just as effective if not more effective than normal maintenance. Here it is. Never service your tankless water heater. Ever. Tankless water heaters in the southern regions of the united states suffer from scale build up in the heat exchanger. Manufactures advise flushing the water heater with vinegar or some other gentle acid. The acid in vinegar or CLR break up the calcium and magnesium scale. Ultimately the flush cleans the inside of the copper heater exchanger to make sure that the water heater functions properly.
Alternative tankless service never service or flush the water heater. Leave it alone and use the money you would have spent on servicing on changing the heat exchanger every 5 years. Here are the details: tankless water heater servicing costs between $100-$200 per year. Servicing your tankless water heater adds up quickly plus it can be time consuming to have a technician come to your house every year to service your water heater. Alternatively, changing the heat exchanger only needs to be done every 5 years as opposed to every year. The replacement service costs $600-$800 dollars.