Maison de designer à Triana
The pool. Heated private pool on the top-floor terrace. The host says it's heated during the cooler months, from October to May, and usable summer and winter.
The pool comes up in 28 guest reviews, according to the listing page. I haven't yet found guest reviews that mention the water temperature.
Guide's tip. In winter, heating must be requested when you book or at the latest two days before arrival: don't forget.