Thermostats and Heat Detectors

Before anything else, confirm what powers your system. That single check decides which thermostat will actually run on your wall. Modern Honeywell thermostats require 24 VAC power — a C-wire — and are incompatible with millivolt or high-voltage (120-240V) systems. Get that wrong and you’ve bought a device that won’t function, no matter how good it looks.

For broader project planning, explore WBC’s building materials resources.

This guide splits into two halves. Thermostats control comfort and cut heating bills. Heat detectors are life-safety hardware for spaces where smoke detectors don’t belong. Different jobs, different buyers, but they land in the same category for a reason — both sense temperature and both need to match the application.

Thermostats: Residential, Commercial, and Hospitality

Three classes of thermostat cover three different jobs. A homeowner swapping out an old dial unit, a building manager running rooftop equipment, and a hotel operator managing guestroom energy all need different hardware.

Residential. For a house, you’re looking at programmable and digital units. Western Building Center carries a few Honeywell options here, including the RTH230 5-2 day programmable, the RTH221B 7-day programmable, and the CT30A100 economy heat thermostat. There’s also a manual white digital thermostat in the mix. The 5-2 day splits weekday and weekend schedules; the 7-day lets you set each day independently. For Montana’s long heating season, a programmable setback schedule pays for itself when the house sits empty during the workday.

Commercial. The step up is the TC500A. It’s an advanced, configurable, connected device for commercial buildings that controls and monitors rooftop units, heat pump equipment, and their accessories. It communicates over Wi-Fi, Bluetooth, BACnet IP over Wi-Fi, BACnet MS/TP, and Sylk to integrate with the building automation system. The freeze protection matters here. Its commercial control algorithms include auto changeover, scheduled purge, power-up delay time, freeze protection, demand limit controls, and recovery methods established over decades of use. In a cold climate, that low-end protection keeps equipment and pipes from freezing during an unoccupied stretch.

Hospitality. The INNCOM line — D1, E6, E7 — is built for hotel guestrooms. The INNCOM Direct D1 Thermostat carries an on-board RF transceiver, a passive infrared occupancy sensor, humidity sensor, and outside temperature display. The point of these is occupancy-based energy management. As the key node in an occupancy-based EMS, it receives inputs from a PIR motion detector and wired or wireless door switches to determine guestroom occupancy. When the room is rented but the guest isn’t present, temperature can range up or down within a programmable setback band — saving energy with no impact on guest comfort.

Class	Representative units	Power	Best for
Residential	RTH230 (5-2 day), RTH221B (7-day), CT30A100 economy heat	24 VAC / C-wire	Homes
Commercial	TC500A	24VAC 50/60Hz, 20-30VAC working range	Rooftop units, heat pumps
Hospitality	INNCOM D1, E6, E7/e7w	Low voltage (E6: 12V)	Hotel guestrooms, EMS

Power and wiring — confirm this first

The commercial unit is specific about its supply. The TC500A power supply is rated 24VAC 50/60Hz with a working voltage range of 20-30VAC, requiring a UL listed class-2 transformer or IEC 61558 listed transformer. Wiring runs on standard low-voltage conductor — 18 to 22 gauge secured into the mounting plate terminals. If your existing system is millivolt or line-voltage, these devices won’t work without a different solution.

Programmable setback and the savings

This is why most buyers upgrade. The hospitality figures show the payoff scales with how much intelligence you add. Motion detection only saves 10-20% on guestroom HVAC; standalone EMS with motion plus a door sensor reaches 15-25%; a networked EMS pushes 25-40% — driven by the fact that on average more than 30% of hotel rooms in the U.S. are unrented at any given time. The principle carries to any building: an empty space heated to full setpoint is wasted money.

The commercial unit also fences in the setpoints. On the TC500A, heat setpoints are limited automatically between 40°F and 90°F, and cool setpoints between 50°F and 99°F. That 40°F floor is your built-in freeze guard.

Heat Detectors: Detection Classes and Where They Belong

Heat detectors are the other half of this category, and they’re life-safety equipment — not comfort hardware. In an unheated shop, a dusty garage, or any space where temperature swings and airborne particles would trip a smoke detector, a thermal detector is the right call.

The FST-951 series is the current generation. Notifier FST-951 Series intelligent thermal detectors are direct replacements for the FST-851 Series. The detection class is the spec you match to the application. They use a thermistor sensing circuit offering Class A2S (fixed 59°C), Class A2R (Rate-of-Rise 59°C), and Class C (88°C) high-temperature detection.

Fixed-temperature trips at a set point. Rate-of-rise reacts to how fast the temperature climbs. The 88°C high-temp class fits spaces that already run hot, where a lower threshold would false-alarm.

Feature	Detail
Detection classes	A2S (fixed 59°C), A2R (rate-of-rise 59°C), Class C (88°C high-temp)
Colors	Ivory, White, Black
Connection	Two-wire SLC
Panel compatibility	FlashScan and CLIP protocol fire alarm control panels
Testing	Magnet-activated functional test switch
Security	Built-in tamper-resistant lock

On the build quality and code side: the FST-951 includes a built-in tamper-resistant lock, a built-in functional test switch activated by magnet, and simple rotary decimal addressing — 1-99 on CLIP systems, 1-159 on FlashScan systems. It uses a two-wire SLC connection and carries UL/ULC Listing S2101 and FM Approved certifications. Those listings are what make it acceptable for code-driven installations.

Installation Basics and When to Call a Pro

A residential thermostat swap is within reach for a competent DIY builder. The mounting routine is straightforward: level the mounting plate about 5 feet above the floor and drill 7/32-inch holes for drywall anchors. Use the provided decorative cover plate if you’re mounting to a junction box or concealing paint gaps. Secure the wiring into the terminals using 18-22 gauge wire.

Commercial and life-safety work is a different story. A trained technician is recommended for installation — and for fire detectors tied into a control panel, that’s not optional advice. Getting addressing, SLC wiring, and panel compatibility right is the difference between a working system and a code failure.

One option worth knowing for retrofit jobs where pulling wire is a headache: the battery-powered route. The INNCOM e7w has a battery life of two years and eliminates the need to pull wires, and it’s powered by four AA batteries. Its wireless design also lets it be placed virtually anywhere in a room for precise occupancy detection.

Frequently Asked Questions

Will any modern thermostat work on my system? No — and this is the check to make before buying anything. Modern Honeywell thermostats require 24 VAC power (a C-wire) and are incompatible with millivolt or high-voltage 120-240V systems. Confirm your system’s power type first.

What’s the difference between a 5-2 day and a 7-day programmable thermostat? A 5-2 day unit runs one schedule for weekdays and a second for the weekend. A 7-day unit lets you program each day individually. Western Building Center carries both in the Honeywell line — the RTH230 5-2 day and the RTH221B 7-day.

Why use a heat detector instead of a smoke detector? Heat detectors suit spaces where dust or temperature swings would false-trip a smoke detector — garages, shops, unheated outbuildings. The FST-951 offers fixed-temperature, rate-of-rise, and high-temperature (88°C) detection so you can match the class to a space that already runs hot or dusty.

How much can a setback schedule actually save? The hospitality data gives a useful range. Motion detection alone runs 10-20% savings on HVAC, motion plus a door sensor reaches 15-25%, and a fully networked EMS hits 25-40%. The savings come from not conditioning empty space — which applies to any building, not just hotels.

Does the commercial thermostat protect against freezing? Yes. The TC500A includes freeze protection among its control algorithms, and its heat setpoint floor is locked at 40°F. That low limit is built-in cold-climate protection.

Can I install a heat detector myself? For life-safety detectors tied into a fire alarm control panel, bring in a trained installer. The FST-951 uses a two-wire SLC connection and carries UL/ULC and FM certifications, and proper addressing and panel integration are not DIY territory.