I replaced an HVAC system that still worked very well but was really old (the furnace was 45 years old, and the A/C 30 years old). I did about a year's research and got eleven bids prior to beginning (getting that many bids was an accident too long to explain, but if I hadn't I wouldn't have tripped across these guys, so it was worth it). When California Energy Services arrived, I was initially unimpressed with the salesman, the brand of equipment used, and the price-- so had elected to go with someone else. To its credit, however, California Energy Services did have a good reputation from various reviews. I had given California Energy Systems a courtesy email to let them know I was going with someone else, and I received a return call essentially telling me to write my own contract. Who can refuse that sort of offer? So, I pulled my favorite pieces from other bids and asked for a much lower price to agree to California Energy Services. I'll be damned, they actually accepted it! I'm even getting a year's free maintenance and a Nest Thermostat tossed in that I had not asked for. The installation crew was friendly, the equipment was installed, and works well so far (the true test will be how well everything lasts over the next 20 years or so). The only negative things about these guys is that they arrived 1.5 hours late and left a mess inside the house (construction dust on the furniture and floors, and grease smeared in the carpet because booties weren't worn and drop cloths not used; fortunately, I was able to totally clean everything up). I called and said something to the sales rep and when while I wasn't there when they came back to finish, I was told they took great care not to repeat the first day's mess. For the huge amount of money I saved by going with these guys for a solid brand name, the lateness and mess are both things I can overlook. Will be adding additional insulation to my attic at some point and will definitely call for a bid. Overall, highly recommended.