沸かす

1. Origins, structure, and basic meaning

• Structure: 沸かす (わかす) is a transitive verb for heating water, including water prepared for a bath.
• Basic usage: 湯を沸かした reports boiling water for tea in a kettle, while 風呂を沸かす denotes heating the bathwater during another activity.

2. Common pitfalls and similar expressions

• Referent of 風呂 with this verb
  • 風呂を沸かす does not mean boiling the tub or room itself; it means heating water to prepare a bath. The shared element with 湯を沸かす is change in water temperature.