I am having a problem with my gas central heating system. I have a Lux
500 programmable thermostat that I installed a few years ago. When I came home this evening, my house was extremely hot. The thermostat display was flashing "OL" which I found out means that the temp is above 95 degrees. I turned the switch from heat to "off" and the heat turned off after a few minutes. I removed the cover and changed batteries. Still, when I click the switch back to heat, the heater starts up again even though the temp has dropped to 92 and the setting is on 68. Do in need to replace the thermostat with a new one, or do I have another problem?Thanks, Steve