Thermostats, Smoke Detectors and Carbon Monoxide Detectors

Thermostats control your home’s heating and cooling; smoke and carbon monoxide detectors warn you about smoke, fire and CO hazards. A programmable thermostat takes repeated temperature adjustments off your daily list. Interconnected combination smoke and CO alarms detect both hazards and sound together when one activates, a feature worth buying when bedrooms and living spaces are on different floors.

Smart thermostat or programmable thermostat?

Buy a Wi-Fi thermostat for remote temperature adjustments. Buy a Honeywell programmable thermostat for temperatures that follow your daily schedule. Those are different conveniences: one lets you make changes from your phone, while the other handles the changes you already know you want.

Many smart thermostats learn your preferences over time. Wi-Fi thermostat features can include an alert when the house drops below a temperature you choose. That is a useful feature for a Montana home left empty during winter. Flathead Valley winter lows average 16°F, and inversions hold cold on the valley floor from late October through February. A low-temperature notification gives you a reason to check on the house before your next planned visit.

For a regular workweek, buy the Honeywell five-two-day programmable thermostat. You get one weekday schedule and another for the weekend. For changing shifts or a week when Tuesday looks nothing like Thursday, buy the Honeywell seven-day programmable thermostat. Each day gets its own schedule.

Thermostat type	Schedule arrangement	Buy it for
Honeywell five-two-day programmable thermostat	5 weekdays share a schedule; 2 weekend days share another	A regular workweek and a different weekend routine
Honeywell seven-day programmable thermostat	7 days can each have their own schedule	Shifts, school and activities that change through the week

The mistake is buying a schedule that fights your household. Separate daily programming is useful when your days differ; a shared weekday schedule keeps a regular week simple. If you prefer to make every change yourself, buy a manual digital thermostat. Manual adjustment is exactly what that control is for.

Match a replacement thermostat to the equipment and wires

Start with the heating and cooling equipment, then choose the controls you want. Check the system type, its heating and cooling stages, and the existing thermostat terminal connections. A stage is an operating level: a single-stage system switches on or off, while a multistage system can run at different capacities. The replacement thermostat must control the stages your equipment uses.

Most residential thermostats operate on low voltage, typically 24V AC. Line-voltage controls are a separate choice. Match the voltage and equipment before choosing between manual, programmable and smart features.

The common wire for a thermostat is the C-wire. Many modern smart thermostats need it for continuous power. That makes the existing wiring part of the buying decision, especially when replacing an older control. Identify wires by their terminal connections, not their colors; thermostat wire colors do not have standardized functions.

For thermostat replacement, turn off power to the heating and cooling equipment before wiring work, and photograph the existing connections with terminal markings visible. Heat pumps, multistage equipment and work requiring a new C-wire are jobs for an HVAC professional. That gets the new control matched to the equipment it has to run.

Winter is Montana’s interior renovation season. Put thermostat replacement on a planned workday, with the equipment and wiring identified before the old control comes off the wall. A cold house is a poor place to start sorting out compatibility.

How to set a Honeywell digital thermostat

For everyday use, select the heating or cooling mode for the season and set the temperature you want. For programming, enter the times and temperatures that match when you wake, leave, return and sleep, using the periods your control provides. On a five-two-day thermostat, build the weekday and weekend routines. On a seven-day thermostat, work through each day.

A manual temperature change on a programmed control typically lasts until the next scheduled period. If the temperature keeps returning to a previous setting, check the schedule. The control may be doing exactly what you programmed.

On a basic on-off system, turning the thermostat above your comfort setting does not warm the house faster. Set the temperature you actually want. Great Falls chinooks can swing outdoor temperatures quickly, so a readable display and straightforward adjustments matter when the weather changes during the day.

“EM heat” means emergency heat. Some heat-pump systems use a gas or oil furnace for backup or emergency heating. Match that function to the equipment in your home when choosing a replacement control.

How to change the battery in a Honeywell thermostat

For a Honeywell thermostat with a pull-off face and an AA battery compartment, pull the thermostat away from its mount, insert fresh AA batteries in the indicated direction, then align it with the mounting plate and push gently until it snaps into place. Some thermostat faces release from the bottom or use a locking tab, so establish how yours releases before pulling.

Wired equipment can still leave you with batteries to maintain. Thermostats may use batteries for primary or backup power, and low-battery alerts tell you when replacement is due. A visible battery warning is a feature worth having during heating season.

Before replacing a troublesome thermostat, check its batteries, heating or cooling mode, and programmed settings. Check the air filter too; a better thermostat cannot make up for a clogged filter. If those checks do not explain the problem, have an HVAC technician check the equipment.

Ten-year battery smoke and combination alarms

The First Alert slim-profile photoelectric smoke alarm two-pack gives you two smoke alarms with ten-year battery power. Buy that pack when you need two smoke alarms and want a slim profile. Photoelectric sensing detects the larger smoke particles associated with smoldering fires.

Choose a combination smoke and carbon monoxide alarm when you want both hazards detected in one unit. Ten-year battery combination alarms are one option; battery-powered and hardwired versions are also available within this category.

CO detection matters through Montana’s heating season wherever wood, propane, natural gas or oil is burned. Incomplete combustion of those fuels can produce carbon monoxide, which is invisible and odorless. A smoke alarm and a CO alarm have different jobs. Buy combination detection when you need both jobs covered.

For bedrooms separated from the main living area, choose compatible interconnected combination alarms. They sound together when one activates. That shared warning is the feature to prioritize across floors.

Battery-powered or hardwired smoke alarms?

Buy a First Alert battery-operated smoke alarm where you need placement independent of existing alarm wiring. The battery-powered smoke alarm with an LED is another choice in this group. Keep the power arrangement central to the decision: a battery-powered unit lets you address a location without depending on a hardwired setup.

Buy the First Alert hardwired smoke alarm with battery backup for an existing compatible wired alarm setup. The backup operates during a power outage. Hardwired does not mean battery-free, so include the backup battery in your maintenance routine.

For smoke-alarm coverage, include bedrooms, the areas just outside bedrooms and every level, including the basement. Use the test button to check alarm function. Ten-year battery power is a useful buying feature, and testing remains part of owning the alarm.

The Pick

Buy the Honeywell five-two-day programmable thermostat for a regular weekday and weekend routine. Buy the Honeywell seven-day programmable thermostat when each day needs its own schedule. Choose a manual digital thermostat when you want direct, simple adjustments.

For smoke detection, buy the First Alert slim-profile ten-year battery two-pack when you need two alarms, a battery-operated alarm where wiring does not serve the location, or the hardwired alarm with battery backup for a compatible wired setup. Choose interconnected combination smoke and CO alarms when you want both hazards detected and the warning shared through the house.

Frequently Asked Questions

How do you change a thermostat?

A replacement thermostat has to match your equipment’s voltage, heating and cooling stages, and existing wiring before the swap starts. Turn off power to all heating and cooling equipment, then photograph the connections with the terminal markings visible. Label wires by those markings, keeping both designations when a terminal has a shared label, and follow the replacement’s installation instructions. Heat pumps, multistage systems and installations needing a new common wire are work for an HVAC professional.

How do you change the battery on a Honeywell thermostat?

If your Honeywell thermostat has a pull-off face and an AA battery compartment, pull it from the mount and replace the batteries with fresh AA batteries facing the indicated direction. Align the face with the mounting plate and push gently until it snaps into place. Some faces release from the bottom or have a locking tab, so check the release before pulling harder.

How do you set a Honeywell digital thermostat?

For a programmable Honeywell thermostat, set the times and temperatures for the daily periods your control provides, such as wake, away, home and sleep. Some controls let you copy one day’s schedule to another, which saves entering the same routine repeatedly. If yours has Smart Response, set the time you want the house comfortable; that feature starts heating or cooling early enough to reach the temperature at the programmed time.

What is the common wire on a thermostat?

The common wire is the C-wire, and many smart thermostats need it for continuous power. Identify it by its terminal connection, because wire color doesn’t reliably tell you its job. Before fitting a connected control, check its power requirements against the existing wiring; some installations need a new C-wire or an external transformer with professional assistance.

What does EM heat mean on my thermostat?

EM heat means emergency heat on a heat-pump system. A heat pump uses its compressor for heating and cooling, and some systems have a gas or oil furnace for backup or emergency heating. When choosing a replacement thermostat, match its emergency-heat capability to that equipment as well as its normal heating and cooling stages.

Is a smart thermostat better than a programmable thermostat?

A programmable thermostat handles temperature changes you can schedule ahead of time; Wi-Fi control lets you make adjustments remotely, and many smart thermostats also learn your preferences. A Honeywell programmable thermostat is a practical fit when the main job is following your household’s routine. If you want to check on an empty house, look for remote control and a low-temperature alert, then verify the wiring and equipment compatibility before choosing.