Hi All - We have a tankless water heater and live in So Cal. During our winters (mild, but can get to low 40s), the water heater works perfectly. It's the summers where it can get to high 60s at night and 100 during the day. The reason I am mentioning the outside temperature is because I'm trying to figure out why the water that comes out of the shower head gets hotter and hotter the more I try to cool it down until eventually the water heater kicks off and then I'm faced with a cold shower until I'm forced to turn the water flow off completely and restart again. I can't seem to take a refreshing "warm" shower. It's either too hot or too cold. SUMMER ONLY. Any ideas?