We called Nerthling's to look at our furnace which was shutting off without heading the house. The individual I spoke with on the phone clearly explained the cost of the diagnostic and generally what to expect They came out within 2-3 hours of my call at 8 AM. The two technicians where thorough , professional, and polite. They had the furnace repaired by the afternoon They were reasonably priced and honest. I highly recommend them