Apocalypse Revealed # 648
648. 14:18 And another angel came out from the altar, who had power over fire. This symbolizes the heavens of the Lord's celestial kingdom, which are prompted by the goodness of love received from the Lord.
Another angel here symbolizes the heavens of the Lord's celestial kingdom, because he was seen to come out from the altar. For an altar symbolizes worship of the Lord prompted by love, as may be seen in no. 392 above. Moreover, fire symbolizes love (no. 468), and fire on an altar symbolizes Divine love (no. 395).
We are told that the angel had power over fire because angels guard that love in themselves.