We have had our pool for two winters and to date have not been able to use it on our Christmas trips. Last year the reason was "Arizona's coldest winter" and we did not start the heater earlier prior to our visit. Although all of our neighbours pools worked with a 24-48 hour warm up time. This year our heater has been on two full weeks before our visit and has not made a difference. We were sold on the energy efficient heat pump? Relied upon the experts and have been let down.