This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
煗 combines 火 (fire) with 耎, which likely contributes the sound. The exact historical development is uncertain.
The left side is fire 火, and the right side 耎 suggests something soft or yielding. Picture a gentle fire warming something soft, but the exact meaning is unclear.
For ダン, imagine a warm down blanket: down -> ダン, and the fire 火 keeps the soft 耎 blanket cozy.