When our heating bills doubled in one month, and our system's red warning light started blinking, we were stumped. Oour geothermal coil system is very unique, and requires a specialized technician. We were told that the nearest technician was located in Troy, New York, and a service call would be prohibitively expensive. Neighbors recommended Deerfield Valley Heating and Cooling, and they sent a specialist. It took two service calls, but he finally isolated the problem--a freon leak in our system--and made the repairs. The technician was reliable, helped educate us about our system, and did a great job overall.