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Tankless water heating evaluation

This week I am continuing in the evaluation of tankless water heaters for use in as the source of domestic hot water in the solar house. According to the rules there appears to be three main areas of the house to are required to have hot water. 1) A shower to be used at least 10 minutes a day, 2) A laundry machine, and 3) a dishwasher. Two sinks will also be considered to be standard equipment, although their water usage is minimal when compared against a dishwasher or laundry machine. One of the most known factors however is the incoming water temperature, which is very important in a tankless design. Since the water for the house is stored in a tank, the temperature of incoming water is highly dependent on the ambient air temperature. A more detailed look into the average temperature during the competition my be required.

My initial concerns about the amount of on-demand power by the tankless systems seem to have been overplayed. The house is connected to the power grid which can assist in the on-demand power load. In addition, the inverters can supply power at the required 240v.

In looking at the rules and the gallons per minute (GPM) required by each device, I have come up with an estimated power for the tankless system that can be compared against other systems for water heating. After comparing against other systems, we will be able to make the optimal choice for hot water heating.


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