Water heater filters are contained in a filter housing.
Hot water heater filter location.
The installation code for a tankless water heater varies a lot by location.
The tac or scale net filters use a big blue housing that installs on the cold water line to feed the water heater.
Since it would not be economical of me to provide the codes for every town in the united states and canada let me just give an example.
Place it under the heater and pipe it into an adequate drain for water disposal.
Install a water heater filter system on the cold water line that feeds the heater to eliminate or sequester these minerals before they get into the heater and create scale.
Water heater maintenance is fairly straightforward and many property owners know how to do the basics such as flushing the tank twice per year checking the anode rod and other aspects.
Water heater maintenance clean the filter.