I replaced my 20 year old 4 ton WF Premier with a CM TE-30 4 ton unit in August. The WF was working just fine, but being 20 years old and finishing a complete remodel of the home left only the geo unit to be updated. I only owned the home about 4 months before installing TE-30 and during much of that time the old geo unit was turned off during the remodel. One thing I did not like about the old setup was the large pressure tank and single speed pump I had for my well. The noise from the Taco Valves was noisy when the pressure tank exceeded 50 PSI. For the new setup I installed a Grundfos variable speed pump and run it @ 40 PSI for the geo unit. The well in my home is only for outdoor use and the geo unit. My installer will be installing a 30 PSI valve on the geo unit (per the manual instructions) and so I can run higher pressure on my outdoor spigots without affecting GPM through the geo unit. My system is open loop. Anyway, the new CM TE-30 has been spectacular so far. My home is 2300 sq ft up and 2300 sq in the basement also finished. My highest electric bill for the entire home August through December of this year has been $97. My home was remodeled with LED lighting and newer energy efficient appliances; however, I also have quite a few 1970s-1990s full size arcade games that draw significant power and we keep the home 72F year around. I also have 3 refrigerators. Out KwH rate comes in @ 11.8 cents. Electricity is fairly inexpensive here. I do have a natural gas dryer, range, hot water and fireplaces. Our gas bill averages $35 per month. As far as efficiency goes I can't see a better solution. Initially, the installer set up the thermostat to control the modulating valve using DeltaT of 9F heating and 16F cooling. During the first two days I kept getting LT1 lockouts because the valve would overshoot trying to obtain the correct DeltaT. The solution was to manually program valve % positions and disable the DeltaT programming. My water temperature here is a constant 55F in the summer and 53.5F in the winter. I set the cooling 1st stage at 62% and 72% for stage 2. This yields a 20F DeltaT for cooling. For heating I set the valves at 65% and 75% and that yields a 11F DeltaT with a 42F LWT and 39.5F LT1 Temp. I think I could restrict the valves down to 62 and 72% for heating and still be safe avoiding LT1 low temps. Since manually setting the valves I have had zero problems and love the operation of the unit through the easy to use thermostat. I have noticed that the contactor does make a mild constant buzzing sound even when the unit is not running and the compressor seems to make more of a humming noise than it was new, but this may have always been this way and now I am just more sensitive. I would highly recommend this product to anyone considering upgrading their HVAC system.