Most of our heat is hot water. We replaced the old cast iron boiler years back. That saved $100 a month on the winter heating bills. Our A/C is the old system. I would estimate the old compressor unit to be 50 years old. It still works and really works pretty well. Not too energy efficient though. The Compressor and fan are both 220 volt units and the lights will flicker a second when they both start at the same time. Sometimes when it's really hot, I will just leave the fan run constantly and the t stat will cycle the compressor as needed. Air circulation to prevent temp stratification is the key.