My central air conditioning unit died at the beginning of the summer, which prompted me to look into replacing it with a heat pump. After getting quotes from several other contractors, I ended up pulling the trigger with SumZero. My experience has been, overall, positive. I went into this with a lot of information and understanding of heat pump systems, and a good idea of what I was looking for. SumZero was very patient answering my questions, many of which were deeply detailed and in-the-weeds, and they were willing to accommodate my specific choice of heat pump (a Fujitsu VRF system which could work with both the ducted floors of my house AND the basement, which is ductless). The installation itself was painless - the installers were respectful, competent, and professional. The system has performed quite well over the (admittedly mild) winter, and my $10,000 rebate from Mass Save came through. I've had no problem getting through to SumZero when I've had further questions or needed help, and I've since recommended them to neighbors making the switch to a heat pump.