Hot water

Do you need it?

A kettle plus cold plumbing is simplest. Built-in hot water earns its space for daily showers and dishes but adds energy, freeze risk, valves, relief devices and maintenance.

Heater choices

Electric tanks are simple but energy-heavy. Propane tank/tankless units require listed RV installation, combustion air and exhaust. Hydronic and engine-coolant exchangers integrate heat efficiently but add complexity and must prevent cross-contamination.

Tank vs tankless

Tank heaters store energy and deliver low-flow hot water but occupy space and lose standby heat. Tankless heaters save storage and can run longer, yet need minimum flow, stable pressure and substantial fuel/power.

Temperature safety

Hot storage can reduce microbial growth but increases scald risk. CDC advises thermostatic mixing at the tap when storage is above 120°F. Use the heater's required pressure-temperature relief valve, drain and approved mixing arrangement; never cap a relief outlet.

Build rule

If you cannot reach it, isolate it, drain it and explain its pressure/temperature or water-quality job, it is not ready to hide behind a wall.

CHAPTER CHECK

• I can explain the purpose and failure mode of each item in this chapter. • I know which manufacturer limit or water-quality claim controls my choice. • I added the valve, access, drain, measurement or maintenance task to my drawing/checklist.