I had an NDV049A111CTR installed 3 weeks ago that replaced an old FHP (3.5 ton I think) that shot craps after 8 years. Not sure what model it was though. The original loop and ductwork remained the same except for some modification to the return air duct at the furnace. The thermostat was replaced with a programmable WaterFurnace stat. I have a water heater and storage tank that were also reused and hooked up to the new furnace using new copper pipes. I have a couple questions regarding this new unit. 1. The furnace will run 35 to 40 minutes every hour even though the outside temperature is in the mid teens. It is in 1st stage almost all the time so I am wondering if this is possibly just normal operation? The FHP never seemed to run this much. 2. The unit is located in the basement and makes an annoying hum/vibration that can be heard easily throughout the house upstairs. It is much less noticable near the unit. The noise is also much more prominent in the 1st stage of operation. If running in 2nd stage it is a lot quieter. Is this normal? I used a cheap thermometer and the air entering the unit is 69 degrees and the air exiting the unit is 86 degrees when running in stage 1 after about 20 minutes. I had the installer, whom I have been pleased with, return to check the unit and they say all is fine and operating properly. I was not home but the technicians work order noted the following - Temperature drop in loop 9 degrees. Check airflow, temp rise at coil 29 degrees. Checked desuperheater operation.Checked unit amp draw. Check blower speeds. Unit working ok. I am still concerned however with the run time and annoying noise or vibration. Any insight or suggestions would be much appreciated.