We experienced intermittent problem with the heater of our downstairs heating and air system. Went through 3 different service companies over a 3 year period attempting to fix the problem. As I said, the problem was intermittent so in all fairness I understand it was hard to diagnosis when the unit was working properly. The service tech from Choates caught it when it faulted while he was working on the unit. His diagnosis was correct and after ordering and installing replacement part the heater now operates correctly at all times, fortunately just in time for a week of sub freezing weather. I was also pleased that when the replacement part arrived Choates came out and installed it without charging for a second service call. Very satisfied with Choates service.