installed my wyze thermostat and now the heat won't turn off, it just runs constantly, what did i do wrong?

Diagnosis

The primary cause of a Wyze Thermostat calling for heat indefinitely is a "closed-loop" short circuit, typically caused by incorrect wiring at the backplate or a failure in the C-wire (Common wire) connection. When the thermostat is not receiving consistent 24V power from the C-wire, it may attempt to "power steal" or fail to trigger the internal relay to open, leaving the W (Heating) terminal energized. This creates a constant signal to your furnace or boiler, telling it to run regardless of the temperature reading on the screen. Another common culprit is a jumper wire error. If you have a system that requires a jumper between Rc and Rh, but the Wyze internal bridge is malfunctioning or the physical jumper is improperly seated, the power can bleed directly into the heating circuit. You can confirm this by removing the thermostat faceplate from the wall; if the heat stops immediately upon removing the faceplate, the issue is definitely in the thermostat wiring or settings. If the heat continues to run even with the faceplate removed, you have a short in the wall wiring or a stuck relay at the furnace control board.

How to Fix It

Follow these exact steps to isolate and resolve the constant heat issue:

1. Shut off the power to your HVAC system at the main breaker panel to prevent blowing a fuse on the furnace control board.
2. Remove the Wyze Thermostat faceplate by pulling it gently away from the wall base.
3. Inspect the W (White) wire. Ensure it is stripped back exactly 1/4 inch and is firmly clamped into the terminal. If the wire is loose or barely touching the contact, it can cause intermittent signals or constant calls.
4. Check the C (Common) wire. The Wyze Thermostat requires a dedicated C-wire for stable operation. If you are using a "C-wire adapter" or "Power Extender Kit," verify that the wires at the furnace end are seated tightly in the terminal strip.
5. Verify the Rh and Rc wires. In most standard heating systems, the red power wire should be in Rh. If you have a jumper wire installed between Rc and Rh, remove it; the Wyze Thermostat handles the bridge internally. Having an external jumper can sometimes cause feedback loops.
6. Check for "wire bridging." Ensure no stray copper strands from the Red wire are touching the White wire terminal. Even one tiny strand of copper crossing the gap can trigger the heat.
7. Reattach the faceplate and restore power. Go to the Wyze App, navigate to Settings > Advanced > Equipment and ensure the "Heat Type" (Gas, Electric, or Oil) is correctly matched to your system, as incorrect configurations can lead to erratic relay behavior.

If That Didn't Work

• Check the Furnace Fuse: Inspect the 3-amp or 5-amp blade fuse on the furnace control board. If the fuse is blown due to a short during installation, the system can sometimes "fail-safe" into a permanent-on state depending on the board model. Replace the fuse and re-test.
• Test with a Jumper: With the thermostat removed, take a small piece of insulated wire and briefly touch the R terminal to the W terminal. If the heat kicks on and then turns off immediately when you remove the jumper, your furnace is fine and the issue is a defective Wyze relay.
• Verify C-Wire Voltage: Use a multimeter to measure the voltage between the R and C wires. You should see between 24V and 28V AC. If the voltage is lower than 22V, the thermostat may be rebooting constantly, causing the heat relay to "stick" in the ON position.
• Factory Reset the Device: Perform a hard reset by holding the reset button on the device for 10 seconds. This clears any software glitches in the heating algorithm that might be ignoring the target temperature set-point.

Heads Up

• Avoid Over-stripping: Never leave more than 1/4 inch of exposed copper outside the terminal; this is a high-risk area for short circuits that can fry the thermostat's logic board.
• C-Wire Necessity: Do not attempt to use "battery-only" workarounds or "power-stealing" tricks with the Wyze Thermostat; it is designed for 24V C-wire power and will behave unpredictably without it.
• Check Air Filters: If the heat runs constantly but doesn't actually warm the house, your furnace might be hitting a "high-limit switch" due to a dirty filter, causing the system to cycle rapidly or run the blower without heat.