The easy energy-savers: electronic thermostats can make cutting energy bills a no-brainer.(Buyers Guide)

Rising heating bills and the threat of heating-oil shortages this winter have given energy conservation renewed urgency. And if you live in a warm-weather area, odds are you've also felt the pinch as the cost of keeping cool skyrockets. Fortunately, you can cut those costs as much as 20 percent by lowering your home's thermostat 5[degrees]F at night and 10[degrees]F during the day when nobody is home--or, in warm climates, raising it that amount. Setback thermostats take much of the hassle out of doing that by handling the adjusting for you. You may still find some electromechanical versions like the $120 Honeywell T8090A we looked at while testing for this report; while good overall, it couldn't match the response and flexibility offered by the best of the electronic models we focused on.

Many of these let you set different schedules for different days--helpful if your at-home time varies. Many also tell you when it's time to change your furnace or A/C filter and how long the heating or cooling system has been running. And several switch from heating to cooling control automatically. A couple even indicate whether your heating or cooling system is malfunctioning. Better yet, programming all of these electronic setback thermostats is far easier than it was for earlier programmable units.

That and prices of less than $60 for many make replacing even a working, non-programmable thermostat worth considering. Many homes use just one thermostat to control the whole house. If your home has several heating or cooling zones, you'll need a setback thermostat for each zone to maximize energy savings and convenience throughout the house.

SIZING UP YOUR OPTIONS

The 21 electronic setback thermostats rated for this report provide a range of flexibility.

You get the most schedule options from seven-day models like the Lux TX9000, $55, which let you set different programs for different days--usually with four possible temperature periods per day. You'll pay nearly three times as much for the $145 White Rodgers 1F97-371. But this unit's multitude of features includes the ability to continue working even if its batteries die, since it draws power from the heating or air-conditioning system--unique to this and the White Rodgers 1F90-371 and 1F80-71 in this test. Still another notable White Rodgers feature on models 1F87-51, 1F77-51, and 1F80-51 are secondary switches that keep temperatures from getting too high or low should the batteries die. These are two innovations we wish other brands would adopt for their thermostats.

You can also opt for simpler models that do less but involve less programming. Single-day electronic units like the Honeywell CT2700 allow two daily temperature changes that apply to all days. Fewer options don't necessarily bring a lower price, however; at $50, this model costs almost as much as the seven-day Lux.