It’s winter and outside temperatures can fluctuate drastically, which means more work for your home heating system. So what are the best winter thermostat settings for a home thermostat? Most people try to strike a balance between personal comfort and fuel economy — no one enjoys an inflated energy bill at the end of the month. Here are some things to take into consideration when you’re setting your thermostat for winter weather.
We all know that setting a thermostat lower will save energy. But how much setback does it take to realize savings? Does it matter how long the thermostat is set back? These are questions we don’t often consider. But the answers do matter, and they have to do with two kinds of “temperature differentials.”
This is the difference between thermostat settings — the degree difference between your starting temperature and how far back you set the thermostat: the greater the difference, the greater your fuel savings. For example, if you normally keep your thermostat at 72° F and set it back ten-degrees to 62° when you’re gone, you’ll save more than if you set it back just five-degrees to 67°F. Similarly, the longer you leave the thermostat set at the lower temperature, the greater your savings. If you leave the setback for just an hour or two, it won't make much difference. However, leaving it set lower overnight on a consistent basis will definitely result in savings. So it’s a combination of the amount and duration of setback that will reduce the heat loss from your home and save on fuel usage and costs.
The other differential to consider is the difference between outside and inside temperatures. If the outdoor temperature is 50°F and the indoor temperature is 70°F, you have a 20-degree differential — not too great of a difference. But, if it’s negative ten-degrees outside and your home is at 70°F, now you’ve got a huge difference of 80-degrees. At that kind of degree differential, your home will lose heat at a much faster rate than at a 20-degree differential. So, lowering your indoor temperature as low as is reasonable will lower that differential and slow heat loss from your home. In fact, while you’ll save some energy anytime you set back your thermostat for a long duration, the most heat energy is saved when you set back during the coldest weather, when your home loses the most heat. By reducing the thermostat set point, you change the indoor/outdoor differential, slowing heat loss.
Furnace Operating Limits
Obviously there are limits — both to comfort and efficient use of your heating system. All furnaces have a low temperature operating limit. Most manufacturers state that the return air temperature entering the furnace must be at least 60°F, although some are as low as 55°F. Heat exchanger damage can result if the furnace is operated below the manufacturer’s minimum. The other risk is freezing pipes. Keep in mind that your thermostat is reading the temperature in the middle of the home at eye level. But in the lower areas where water pipes may be located, the temperature will be lower, possibly much lower. If you set your thermostat to 50°F when you leave for vacation, you may subject some areas of your home to freezing temperatures, particularly in older homes with less insulation. It’s best to follow manufacturer guidelines and keep it at 60°F when you’re gone for a long time.