Disclaimer
Disclaimer
Researched guidance, not professional advice. WaterHeaterCalc publishes calculators and buying guidance compiled from published test procedures, code tables, manufacturer specifications and installation manuals. It is general information. It is not a sizing, a design or an inspection of your installation, and it does not replace the judgment of the licensed trade that signs the permit.
The things that genuinely hurt people
- A water heater is a pressure vessel. The temperature and pressure relief valve is never capped, plugged or removed under any circumstances. A valve that will not open when the test lever is lifted has failed and must be replaced. The discharge pipe runs full size to within six inches of the floor, with no threads on the end, no valve in it and no upward run.
- Gas line, flue and vent work belongs to a licensed plumber or gas fitter. An undersized gas line starves a burner and a starved burner produces carbon monoxide. Backdrafting on an atmospheric vent is real and invisible. A working carbon monoxide alarm belongs on every floor of a house with a gas appliance.
- Scalding. Water at 140 F scalds a child in seconds. 120 F is the common setpoint guidance, while Legionella control argues for storing hotter and mixing down at a thermostatic mixing valve. That tradeoff is a decision for your household, and this site presents both sides rather than choosing for you.
- Electrical. Turn the breaker off and verify with a meter before opening an access panel: both legs of a 240 volt circuit are live. Never energise an element that is not submerged.
Codes vary
Code tables reproduced here are from widely adopted model codes, and your jurisdiction may have adopted a different edition or amended it. The authority having jurisdiction is the authority, not this website.
No testing claims
We do not test products in person and never claim to. Where a manufacturer does not publish a figure, this site says so rather than estimating one.
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