My heater is 9 years old and never had a problem before, on christmas eve this year it stopped working brought out a tech he said the transformer was burned out. Replaced it good to go, last week it went out again replaced it again, last night went out AGAIN I am not a service tech but am sick of paying them to "fix" it. What could some of the possilbe reasons be for this happening, the transformer going out not the techs.

Short circuit to the 110V transformer
Check the wiring of the unit coming from the transformer and also the thermostat
Good luck

You have a short in the low voltage side of the system. If it's a heat pump? You need to check the wires on the low & high pressure switch-- check the defrost thermostat and the reversing valve. All of those are low voltage controls and are known to short out on the equipment.