Smart thermostat guide
Honeywell Home ElitePRO S1100 Smart Thermostat THX1100B4 (Black)
Professionally installed systems up to 4H/2C heat pump or 3H/3C conventional, with IAQ equipment
Resideo's trade-channel 5-inch touchscreen thermostat with Redlink 3.0 sensors, control of up to two IAQ devices and Matter; the installer guide lists no doorbell video for it. Honeywell says it requires a pro for installation and warranty, and the user guide says the 5-year warranty may be void without professional installation.
Listing checked . Confirm the model, included parts and availability before ordering.
Published specifications
- Maker and listing: up to 4H/2C heat pump or 3H/3C conventional
- Maker: dual fuel, fan-coil, PTAC and radiant compatible; optional EIM
- Maker: hardwired; listing: C wire required; THP9045A adapter sold separately
- Maker: Wi-Fi 2.4 and 5 GHz, Redlink 3.0; guide: BLE, radar 61.5 GHz
- Maker: 3.54 x 5.25 x 0.96 in; 5-inch display; IAQ up to 2 devices
- User guide: 5-year limited warranty, may be void without pro install
Fit and limits
Strengths
- Supports up to 4H/2C heat pump or 3H/3C conventional systems
- Controls up to two IAQ devices and reads humidity, VOC and estimated CO2
- Five-year limited warranty, per Honeywell and the user guide
Caveats
- Trade product: warranty may be void if not professionally installed
- No video doorbell connection, per the installer guide
- Room sensors, outdoor sensors and the EIM are not in the box
A trade thermostat: read the warranty condition first
The ElitePRO S1100 is a Resideo trade thermostat under the Honeywell Home name. Honeywell's product page says it requires a pro for pricing, installation and warranty. The S1100 user guide states a 5-year limited warranty and adds that, as a trade product, the warranty may be void if it is not installed by a professional.
The installer guide, which lists THX1100B4 as the black S1100, warns that the product must be installed by a trained, experienced HVAC professional. We do not give wiring or setup steps here.
What this listing is
The listing's model and part number is THX1100B4/U, matching the SKU on Honeywell's S1100 page. The S1100 user guide lists two models: THX1100W3, the white thermostat, and THX1100B4, the black thermostat. Honeywell gives 3.54 by 5.25 by 0.96 inches, and the listing gives 0.96 by 5.24 by 3.54 inches.
Honeywell's page lists the box contents as the thermostat, the UWP wall plate, a decorative cover plate with J-box adapter, mounting hardware and literature; the listing agrees. The installer guide notes that kits may include other accessories.
Stages and systems
Honeywell's page and the listing say the S1100 works with systems up to 4 heat/2 cool heat pump or 3 heat/3 cool conventional, and is compatible with dual fuel, fan-coil, PTAC and radiant systems. Modes are heat, off, cool, auto and emergency heat, and program types are time-based or smart away, residential or commercial.
Both list an optional equipment interface module (EIM). The installer guide shows a 2 heat/2 cool gas furnace layout and a heat pump with auxiliary heat layout without the EIM, and points to online documentation for other layouts.
Power and connectivity
Honeywell's S1100 page lists the power source as hardwired, and the listing says hardwired with C wire required. The installer guide says that where there is no C wire or spare wire and the old thermostat used both Y and G wires, the THP9045A C-wire adapter, sold separately, may be used.
Honeywell lists Wi-Fi on 2.4 and 5 GHz and Redlink 3.0. The installer guide lists Bluetooth Low Energy, Redlink at 900 MHz and radar at 61.5 GHz, with input ratings of 24 V, 60 Hz, 0.11 A in its specifications and 2.6 VA in its wiring section.
Air quality, sensors and app
Honeywell's page says the S1100 can control up to 2 IAQ devices and monitors indoor humidity, VOC and estimated CO2. It lists Redlink 3.0 for wireless room sensors, the EIM and outdoor sensors; none of those is in the box list.
The S1100 user guide covers the First Alert by Resideo app, room priority with wireless sensors, humidity and ventilation menus when IAQ control is configured, and Matter setup. The installer guide lists video doorbell connection as S1200 only. Heat setpoints run from 40°F to 90°F and cool from 50°F to 99°F unless range-stops are set.
Warranty
The S1100 user guide states a 5-year limited warranty that may be void if the thermostat is not installed by a professional, points to resideo.info/US-Warranty-THERMOSTAT for terms, and says Resideo Customer Care at 1-800-633-3991 will mail a printed copy.
Honeywell's page and the listing both list 5 years. Neither repeats the professional-installation condition. We did not read the written warranty itself.
Check the current listing
Confirm the model, included parts and availability before ordering.
Primary sources
- Honeywell Home ElitePRO S1100 Smart Thermostat product page and specifications (SKU THX1100B4/U)
- Resideo ElitePRO S1100 Smart Thermostat User Guide 33-00737EF-01
- Resideo ElitePRO S1100 & S1200 Smart Thermostat Installer Guide 33-00706EF-02
Primary sources checked .
Compare with
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Simple single-transformer systems with one stage of cooling, on a 2.4GHz network