ESI Thermostat Not Working? Simple Checks Before You Call an EngineerIf your ESI thermostat is not working, it can feel as though your boiler is not working or your central heating is not working, particularly during colder months. In many cases, the problem is straightforward and can be resolved without calling an engineer.This guide explains how to replace the batteries correctly, how to use the manual override, and when it’s time to contact a professional for boiler repair.Replace the Batt...