Given your description of your system, we presume that you are already paying Rate DT.
Even though oil prices are at their lowest in five years, you should not heat only with oil. To maximize your savings with Rate DT, you should choose the more economical energy source based on the outdoor temperature and price. Given current oil prices, you should run your dual-energy heating system on electricity when the temperature is equal to or above −12 °C or −15 °C, depending on where you live, especially since your heat pump also reduces your electricity consumption for heating. In very cold weather, it is best to heat with oil. For more information, visit our Rate DT Web site.