I have an old Honeywell Thermostat model # T651A1269 and there are 5 wires - Blue, Red, Brown, Black, White. The wires are hooked up to numbers not letters. The Red wire was hooked up to a separate on/off button. The new thermostat has letters in the back of it and it is difficult to hook up. Anyone that can help please write a comment. Thanks in advance.