The short answer
A tankless installation touches several trades: water connections, gas line sizing and venting for gas units, and 240-volt circuits for electric ones. Most owners hire it out: the Harvard Joint Center for Housing Studies found DIY was 13.1% of spending on replacement projects such as HVAC and systems in 2023.
Have ready
- Your fixtures at once and winter rise (size planner).
- The unit's gas load or amps (requirement calculator).
- The model's installation manual: venting, clearances, valves, condensate.
Distribution
Water heaters reach homes mainly through plumbing wholesalers and retail: A. O. Smith reports selling through about 800 independent wholesale plumbing distributors and four of the six largest home center chains.
Products mentioned
Questions readers ask
Can I install a tankless water heater myself?
Water connections are within reach of some owners, but gas line sizing, venting and 240-volt circuits are licensed work in most places, often with a permit and inspection.