For this call I performed a evaluation. The initial reason for the visit is because home owner stated they have been hearing a loud noise on and off and they weren't sure if it was a HVAC unit or their water heater. No significant abnormalities were noted within the unit during inspection, I could not replicate The Noise Within the HVAC unit. Homeowner stated they are going to see if it might be their water heater I offered a plumber to do a free inspection but they decided to wait until they hear the noise again. Upstairs unit has a faulty thermostat homeowner is going to purchase a thermostat and a base for the thermostat and possibly call back to have it installed. Homeowner would like me as their prefered Tech. Thank you for choosing for experts, have a great day!