1. Is the water heater itself hot? if not, it’s not a hot water heater.
2. It heats water to make it hot. That means it’s a water heater, not a hot water heater.
3. It doesn’t heat hot water; hot water is already heated.
Just use water heater.
+. Pet peeve.
My hot water heater has a thermostat, as do most.
The water inside stays hot, according my setting, usually right around 105.
At times in winter when I have been out hunting, fishing or shoveling snow, I’m eager to jump into my big clawfoot tub to soak and relax.
On those days I kick up the thermostat a few degrees...thereby heating my already hot water.
You are still wrong. Or should I drop the “still”?