Thermostats

Your thermostat is the control center of your heating and cooling system. It decides when the system runs, for how long and, on newer equipment, how hard. A good match keeps your home comfortable without wasting energy, while a poor one can leave rooms uneven or keep your system from using features you paid for.

Choosing a thermostat starts with your equipment, then the way your household lives. Before they upgrade, most Libertyville homeowners want to know which type fits, what a smart thermostat really saves and whether it will work with the system they already have.

Which Type of Thermostat Is Right for You?

There are four main types. Which one fits depends on your system and how much you want the thermostat to do on its own:

A programmable thermostat saves energy only if someone sets the schedule and sticks to it, and many never do. ENERGY STAR stopped certifying programmable models in 2009 over questions about their real-world savings. It now certifies smart thermostats instead, based on a year of data from real homes.

How Much Can a Smart Thermostat Save?

According to ENERGY STAR, a certified smart thermostat saves about 8% of heating and cooling bills on average. Some homes save more, depending on climate, comfort preferences, how often the house sits empty and the equipment it controls. You may see bigger numbers in advertising, but the ENERGY STAR figure comes from independent field data. The savings come from features that trim runtime without you having to think about it:

• Schedules and away settings. The thermostat eases off while you sleep or are out, then brings the house back to temperature before you need it.
• Home and away detection. Many models use your phone's location or a motion sensor to tell when no one is home.
• Room sensors. Remote sensors let the thermostat respond to the rooms you're using, not just the hallway where it hangs.
• Humidity control. Some models can run a whole-home humidifier or dehumidifier, so you stay comfortable at a more efficient setting.
• Reports and reminders. Energy reports show how your system runs, and alerts tell you when it's time to change the filter or schedule maintenance.

Should You Turn the Heat Down at Night?

With a furnace, yes. Setting the temperature back while you sleep or are away saves energy, because a cooler house loses heat more slowly. A heat pump is different. When it has to warm the house back up several degrees on a cold morning, it can call on its backup electric heat, which costs several times as much to run as the heat pump itself. With a heat pump, keep setbacks small and use a thermostat set up to recover gradually and limit backup heat.

Will a Smart Thermostat Work With Your System?

ENERGY STAR notes that smart thermostats work with most forced-air systems installed after 1975. Whether a particular model fits comes down to your equipment and the wiring behind your current thermostat:

• The C-wire. Most smart thermostats need a common wire, or C-wire, for steady power to run the screen and Wi-Fi. No C-wire doesn't rule one out, because an adapter or a new wire can often solve it.
• Heat pumps and dual-fuel systems. The thermostat has to be set up for the heat pump's heating and cooling modes and its backup heat. A dual-fuel system also needs one that can switch between the heat pump and the furnace.
• Multi-stage, variable-speed and zoned systems. These usually need professional setup so every stage, speed and zone is controlled correctly.
• Boilers. Many heating-only systems, including most boilers, have just two thermostat wires and no C-wire, so they often need a power adapter or a model made for them.
• Electric baseboard heat. Baseboard heaters run on 120 or 240 volts and need a line-voltage thermostat. A standard smart thermostat can't control them, and line-voltage wiring should be left to a professional.
• Gas wall and floor heaters. Many use millivolt controls that can't supply enough power for a smart thermostat.

Communicating Systems Work Best With Their Own Control

Many variable-speed systems are communicating systems: the thermostat, the indoor unit and the outdoor unit share information to adjust speed, airflow and humidity. They are designed around their matching control, and ENERGY STAR advises using the thermostat the equipment manufacturer recommends for variable-speed equipment. A generic smart thermostat may run the system in a simpler mode that gives up the variable-speed efficiency and humidity control it was built for.

A quick clue: if the wires behind your thermostat connect to terminals marked with numbers or letters like A, B and C instead of the usual R, W, Y and G, your system is likely communicating or proprietary. We can tell you exactly what it needs.

Thermostat Repair or Replacement?

When your heating or cooling stops responding, the thermostat is often the first suspect, but the cause can just as easily be the wiring or the equipment itself. A few quick checks can tell you whether you need a service call:

• Batteries. A blank or dim screen often means the batteries are low. Many thermostats use them, including some that are also wired to the system, so try fresh ones first.
• Settings. Make sure the thermostat is set to Heat or Cool, the fan is on Auto, and a schedule or temporary hold isn't overriding the temperature you chose.
• Location. Direct sunlight, a nearby supply vent or an appliance that gives off heat can make a thermostat read the wrong temperature and run your system at the wrong times.
• The breaker. A wired thermostat shares a breaker with your heating and cooling system. If that breaker has tripped, leave it off and call us. The trip points to a problem in the equipment, and switching it back on can cause more damage.

When a Repair Makes Sense, and When to Replace

If the quick checks don't solve it, a technician can test the thermostat, its wiring and the system to find the real cause. Loose, corroded or damaged wiring, a thermostat in the wrong spot, or settings that don't match your equipment can usually be fixed without a new thermostat. Replacement is the better choice when the thermostat itself has failed, when it's an older dial or lever model, or when it can't run your current system the way it should. It's also a chance to move up to a smart thermostat if you want scheduling, phone control and room sensors.

The Carrier Test Dealer - DS team diagnoses thermostat problems and recommends a repair or a replacement based on what we find.

Schedule Thermostat Repair

What Professional Thermostat Installation Includes

Some thermostat swaps are simple. Others involve a heat pump, extra stages, a missing C-wire or line-voltage wiring, where one wrong connection can blow a fuse on your system's control board or leave it running poorly. Here's how a professional installation goes:

Frequently Asked Questions About Thermostats