The title reads like a train departure, "07:12 Train King's X -> Ely," which suggests the speaker may be writing on a journey, though the poem itself never says so. What it does give us is a feeling of coming home: the speaker is curled up against a radiator, comfortable and settled.
From there the poem turns playful. The speaker asks how the radiator compares to a person, and answers with a cheeky "Incomparable." The jokes that follow, that a radiator doesn't snore and needs less maintenance, sound like affectionate teasing aimed at someone close, perhaps a partner. The tone is light and a little cheeky, but it also hints that this person is the real source of warmth.
The ending is a love offer dressed up as a joke. One is a radiator, the other a two bar heater; one runs on gas, the other on electricity. Different, but a good match. The mood is cosy, funny, and tender.