Our Cape Cod heating systems are usually not designed for sustained temperatures below 0 degrees. When temperatures drop into the subzero range like they have this week, set your thermostat a couple of degrees higher than usual. DO NOT TURN THE HEAT DOWN AT NIGHT! Your heater will be working continuously to maintain your home's temperature. Asking it to bring the temperature up will just put exxtra stress on the system. Just set your thermostat a few degrees higher and then forget it.