"I like the heat."
Translation:J'aime la chaleur.
In American English this could equally mean interior heat. In French could you have used chauffage here? Duolingo didn't like it but in French it would be OK to use as you plopped yourself before the fireplace.
I thought chauffage meant "heating" -
"J'aime le chauffage" sounds quite awkward to be frank. About as off as if I washed my hands in someone's sink and said "I like the plumbing", to try to give an idea. ripcurlgirl is right about chauffage=heating (it can also be slang for heavy flirting, probably regional though)
In the situation you describe one might say "il fait bien chaud", "il fait bon ici"