Atmor 8.5 kW / 240V Tankless Water Heater

I used the map, which shows Southern California in the yellow zone, which includes Florida. Unfortunately, in the High Desert in winter, the temperature often goes into the 20's at night when the electricity is 1/5 the cost of daytime. I usually run the dishwasher during these hours. I should have used the blue zone, which includes Idaho. The water sits outside in a tank, and often gets down to the 30's. It then flows into a tank-type propane water heater which heats it sufficiently, then travels under the house more than 50 feet. to the kitchen and to the dishwasher. There is a large quantity of frigid water in this pipe. Modern Energy Star dishwashers don't use enough water per fill for the hot water to reach the dishwasher before it finishes filling. Dishwashers require hot water, above 120 degrees, to allow the chemicals in the detergent to do their job. My intention was to insert this on-demand heater in the hot water line near the dishwasher. To achieve this temperature from the on-demand heater with frigid water, the flow must be cut way down, just above the minimum necessary to turn it on, about .6 GPM. This works fine for the first fill. After that, there is warm water in the water line. The 900 series heater senses this and shuts down, feeding 95-100 degree water to the dishwasher thereafter, which is insufficient. I could feed the dishwasher and on-demand heater from the cold water line, but I don't want to use electricity exclusively to heat the water for the dishwasher and sink. I will move this heater to another location where there is no hot water line, and where warm water at normal flow rates is adequate. I will replace it with a 905 series with "Thermo Boost" which is designed for "preheated water", and has a dimmer-like system (using Triacs) to accept whatever temperature is coming in and (hopefully) raise it to the desired output temperature (subject to its capacity). There is an additional problem with throttling the flow of the 900 series heater to achieve the desired temperature for the dishwasher. Up on the hill, the well pressure varies from 30-50 PSI. A .6 GPM flow rate at 50 PSI is not fast enough at 30 PSI to turn on the 900 series heater. A .6 GPM flow at 30 PSI will be too high at 50 PSI to produce sufficiently hot water for the dishwasher. (Yes, I could install a pressure regulator.) Therefore, if used under normal conditions for normal use, this heater is great, and very inexpensive. To run a dishwasher on a well with ice cold water that may be preheated, you need a more advanced heater that is designed for this purpose.