Yes, warmer is a Scrabble word!

Adjective

1. Having or producing a comfortable and agreeable degree of heat or imparting or maintaining heat

2. Psychologically warm; friendly and responsive

3. (color) inducing the impression of warmth; used especially of reds and oranges and yellows

4. Having or displaying warmth or affection

5. Freshly made or left

6. Easily aroused or excited

7. Characterized by strong enthusiasm

8. Characterized by liveliness or excitement or disagreement

9. Uncomfortable because of possible danger or trouble

10. Of a seeker; near to the object sought

Noun

1. Device that heats water or supplies warmth to a room