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Energy Saver: Programmable Thermostat Upgrade
(continued ...) I have owned and lived in older houses from the early 1900's. The insulation in those walls was marginal and mostly settled to the lower half of the wall. If this describes your house then consider 58 F (14 C) as your lower limit *6. Don't drop below that limit at least until you read and follow my article about fixing this insulation problem of older houses. This is the fourth step in energy reduction.
Special Provisions for really low thermostat settings in heating season: we want to reduce energy but we do not want anything to be damaged in the process. Special provisions are necessary when very cold outside temperatures (20 F, - 6 C and lower) are expected. The special provisions include but are not limited to things to protect systems that rely on junk heat so as not to be damaged. Especially sensitive areas are sinks, showers, toilets, dishwashers, laundry, outside faucets and similar plumbing on outside walls. Open vanity cabinet and casework doors. Cold air falls and warm air rises. Clear an indoor air path to plumbing on outside walls to take advantage of natural convection. Let faucets drip overnight as flowing water resists freezing by bringing new 'less cold' water to the colder points *6.
Mount insulating polystyrene or similar rigid foam boots onto outside faucets. These faucet boots allow indoor heat to conduct out to the faucet so the water inside does not freeze. The outside boot slows down heat loss through the faucet fixture. Pull your washer out away from the outside wall about a foot. Place incandescent lights in known problem areas so that the bulb's excess junk infrared heat provides protective heat for plumbing. You likely have a bunch of spare incandescent ...