Thermostat shows E07 and cannot connect to Wi‑Fi or app

Safety first: No live wiring work is required for this fault, but do not open the thermostat while powered unless you are qualified.

Steps:

• Power cycle the thermostat by turning off the fused spur for 30 seconds and turning it back on.
• Ensure your router's 2.4 GHz band is enabled and using WPA2 or WPA3 security (avoid enterprise or captive portal setups).
• Move the router or add a Wi‑Fi extender so the thermostat has a strong signal (aim for at least -65 dBm).
• Perform a network reset on the thermostat (refer to the Heatmiser model manual; often via installer menu > Wi‑Fi reset).
• Re-add the thermostat in the Heatmiser app, ensuring you select the correct SSID and password.
• If E07 persists and other devices work fine on the same network, the Wi‑Fi module or main PCB may be faulty and the thermostat may need replacement.