Here's why:
* The letter "e" at the end of the word is silent. This means the "ea" combination creates a long "e" sound, as in "see" or "tree".
* Short vowel sounds are typically found in words with one syllable and a single vowel letter. "Heat" has two syllables, so the vowel sound is not a short one.
Therefore, the word "heat" does not have a short vowel sound.