I have a closed loop geothermal system with a DSH and a 105 gallon Marathon water heater (no buffer tank). This system was installed in a new home and I had no say in the design (and at that time wouldn't have known any better anyways). It is just 2 people living in the house and we have off peak electric for the water heater (on for 7 hours in the middle of the night and 4 hours in the middle of the day). We average 10 showers a week and use a dishwasher and laundry a few times per week. Nonetheless we run out of hot water a couple times per month. I called our electric company to get off of off-peak thinking that was the problem and they had an energy auditor look into it. He said that it is highly unlikely that based on our energy usage that we are actually running out of hot water and that there may be something awry with our system - and the DSH may be the culprit. My simplified view is that if the DSH outputs at 120-130 and the water heater is at 150, isn't the DSH actually cooling the water heater? What are the optimal settings in this set up? Should I turn down the water heater? Should I shut off the DSH valve to the water heater? Thoughts?