Electric warmers require no tealights or exposed flame and instead use a light bulb to heat a ceramic or glass dish to melt the wax and again releasing the fragrance into the air. The electricity and bulb provides a constant source of consistent heat. It wont quite achieve the peak heat of an initial open flame but you won’t get the fragrance drop off either. Your wax will last longer as a result.
Many people with small children or pets prefer an electric warmer as it removes the risk of an open flame but for some the flickering light of the tealight provides a calming glow they don’t want to sacrifice (although many electric burners do have wonderful lighting / flickering effects now).
