If you’re dealing with dry indoor air, cracked floors, or static shocks, having your thermostat automatically manage humidity can make a big difference. Modern smart thermostats can adjust humidity based on outdoor temperature, prevent condensation, and let you control everything from your phone.
Every winter in Edmonton, we get the same question from our customers:
Can my smart thermostat control the humidifier?
The answer is — it depends. It depends on the model of thermostat you have and how many wires are connected between the thermostat and your furnace. Some thermostats include dedicated terminals for humidifier control, while others don’t support accessories at all.
At Vese Heating & Cooling, we install and configure smart thermostats that not only run your furnace and air conditioner but also control your whole-home humidifier automatically. Below, we review the best models available in 2025 and explain what wiring each one requires.
Why Choose a Smart Thermostat with Built-In Humidity Control
Traditional humidifiers rely on a manual humidistat mounted on the return duct — you set it and forget it. But these controls can’t automatically adapt to outdoor temperature or indoor comfort changes.
Smart thermostats fix that problem. They:
Monitor indoor humidity and temperature together
Adjust humidity automatically based on outdoor conditions (frost control)
Let you monitor and fine-tune humidity through an app
Replace the need for a separate humidistat
When wired correctly, these thermostats send a 24 V control signal directly to the humidifier, turning it on only when needed. This saves energy and prevents condensation on windows.
Ecobee Smart Thermostat Premium
Best overall for humidity and comfort automation
The ecobee Smart Thermostat Premium has dedicated ACC+ / ACC- terminals that control a humidifier, dehumidifier, HRV/ERV, or ventilator. It supports both 1-wire (powered) and 2-wire (dry-contact) humidifier connections and includes a Frost Control feature that automatically lowers humidity during cold weather.
Key features:
Built-in temperature, humidity, and air-quality sensors
Frost-control algorithm to prevent window condensation
Works with Alexa, Apple Home, and Google Home
Supports powered or relay-controlled humidifiers
Requires a C-wire for stable power
Minimum wires required (furnace + A/C + humidifier): 6 — R, C, W, Y, G, ACC+.
Honeywell Home T10 Pro Smart (THX321WFS2001W)
Best professional-grade thermostat for multi-stage systems
The T10 Pro Smart thermostat uses its U-terminals to control humidifiers, dehumidifiers, and ventilation equipment. It can operate as a powered or dry-contact output and includes window protection, which automatically reduces humidity when outdoor temperatures drop.
Key features:
Window protection humidity logic
Flexible wiring via U1/U2 or EIM module
Compatible with Aprilaire 400/600/700 series humidifiers
Wi-Fi app control through the Honeywell Home app
Minimum wires required (furnace + A/C + humidifier): 7 — R, C, W, Y, G, U, O/B (for heat pumps).
Emerson Sensi Touch 2
Best budget smart thermostat with humidifier control
The Sensi Touch 2 provides full humidifier and dehumidifier support when wired to the ACC+ / ACC- terminals. It’s easy to configure in the Sensi app and works well for homeowners who want humidity control without paying premium pricing.
Key features:
Works with 24 V humidifiers (not 120 V models)
Humidity setpoint adjustable through app
Sleek, responsive touchscreen
Compatible with Alexa, Google Home, and Apple HomeKit
Minimum wires required (furnace + A/C + humidifier): 6 — R, C, W, Y, G, ACC+.
Google Nest Learning Thermostat (3rd Gen and 4th)
Best option for Google Home users
The Nest Learning Thermostat (3rd & 4th Gen) can control a humidifier through its star terminal, which acts as a dry contact. Because the Nest doesn’t supply voltage on that terminal, most powered humidifiers (like the Aprilaire 700) require a small 24 V isolation relay.
Key features:
Smart Humidity automatic adjustment
Cool to Dry dehumidification using A/C
Controls humidifier, dehumidifier, or ventilation device
Works with Google Home app and voice control
Minimum wires required (furnace + A/C + humidifier): 6 — R, C, W, Y, G, *.
Aprilaire 8920W Wi-Fi Thermostat
Best match for Aprilaire humidifiers
The Aprilaire 8920W is built to integrate perfectly with Aprilaire whole-home IAQ products. It controls humidity, dehumidification, air cleaning, and ventilation in one platform.
Key features:
Full IAQ (indoor air quality) management
Wi-Fi monitoring via Aprilaire Home app
Automatic frost protection
Ideal for Aprilaire 400/600/700/800 humidifiers
Minimum wires required 6 — R, C, W, Y, G, HUM.
Wiring Summary (Minimum Conductors)
System Type | Functions Controlled | Wires Needed | Wires Needed |
Furnace + humidifier | Heat + Fan + Humidifier | 5 | R, C, W, G, ACC / U / star |
Furnace + A/C + humidifier | Heat + Cool + Fan + Humidifier | 6 | R, C, W, Y, G, ACC / U / star |
Heat pump + aux heat + humidifier | HP + Aux + Fan + Humidifier | 7 | R, C, W, Y, G, ACC / U / star |
Professional Installation Matters
While these thermostats are DIY-friendly, adding a humidifier connection involves low-voltage control wiring that can damage your furnace board if wired incorrectly.
At Vese Heating & Cooling, our licensed HVAC technicians will:
Confirm compatibility with your furnace or heat pump
Install new conductors if necessary
Configure the thermostat for proper humidifier operation
Calibrate humidity sensors for accurate readings
Frequently Asked Questions
Q: Can a smart thermostat run a whole-home humidifier?
A: Yes. Models such as ecobee Premium, Honeywell T10 Pro, Nest Learning Thermostat (3rd & 4th Gen), and Aprilaire 8920W can directly control a 24 V whole-home humidifier without a separate humidistat.
Q: Do I still need a manual humidistat?
No. Once a smart thermostat is wired to your humidifier, it replaces the manual humidistat and automatically adjusts humidity based on indoor and outdoor conditions.
Q: Do all thermostats need a C-wire for humidifier control?
A: Yes. The C-wire (common) supplies continuous 24 V power, which is required for Wi-Fi operation and for energizing humidity accessories.
Q: How many wires do I need for a furnace, A/C, and humidifier?
A: Most systems require six wires — R, C, W, Y, G, and one accessory wire (ACC, U, or star). Dual-stage or heat-pump systems may need seven or eight.
Q: Can I install this myself?
A: It’s possible, but not recommended. Humidifier wiring ties directly into your furnace control board, and an incorrect connection can cause permanent damage. Professional installation is the safest choice.
Upgrade to Smarter Comfort in your Edmonton home with Vese Heating & Cooling
Adding a thermostat that directly controls your humidifier removes guesswork, saves energy, and keeps your Edmonton home comfortable all winter long.
Whether you prefer ecobee, Honeywell, Nest, Sensi, or Aprilaire, our team will help you choose, install, and configure the right model for your HVAC system.
Call Vese Heating & Cooling today at (825) 343-6222 or book online to schedule your smart thermostat and humidifier upgrade.
