Left a message for the principal of the firm on a Saturday, when the office is closed. He returned my call the same day while he was out of town! Spoke to their receptionist Monday morning early, who was expecting my call. She set up an appointment for the same morning. Keith arrived, diagnosed the problem in about 20 minutes, located the necessary parts at a supplier, fetched the parts and fixed the problem in about 2 hours. Had heat again. Aside from paying the bill, this was all in all a very pleasant experience with courteous and knowledgeable people. Highly recommended.