Upon arrival system was operational. Homeowner explained that the thermostat would randomly lose power from time to time. Checked low voltage connections at thermostat and at system as well as high voltage connections at system. All connections are tight with no evidence of a short. Replaced eco bee thermostat with a Honeywell 9000 thermostat under warranty. Homeowner also was wondering if an air filter was supposed to be in the Return because we didn’t install 1. System is on the roof and doesn’t have a merv cabinet. Per Matt I went to Home Depot and got them a filter. Finally homeowner wasn’t happy with the job we did installing the new registers. Sent pictures to install so that they can come out and fix them. Homeowners are VERY happy now. System is operational and heating at this time. No charge for visit