The Honeywell T4 is a programmable thermostat for your on/off boiler. The thermostat is suitable for a 24 and 230-volt, 2-wire connector. Thanks to the simple settings, you can start saving energy in no time. You can set up to 6 different temperatures per day. The thermostat is also self learning, so it will automatically adjust the temperature in your home to match your use. The screen lights up when you touch it, which is useful in the dark. Going on vacation? Turn on vacation mode. Once you're back, the thermostat will automatically switch back to the regular week program. The thermostat use 2 AA batteries, which are included by default.