When designing a Thermomax domestic solar water heating system for a family of five, determine first how much hot water the family will be using per average day. ASHRAE recommends 20 gallons per day per person.

The solar water heater storage tank for a family of five with a hot water consumption of 50 liters per day, per person is 375 liters as shown. In the United States, with higher hot water consumption, a 120-gallon tank is used.
The home may have a dishwasher, washing machine, several children taking daily showers or baths during the day, and all of this water usage must be figured into the total water needs.

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In the following four pages we are going to size a solar water heating system for a family of five. They have a hot water requirement of 50 liters per day, per person, with a local Annual Insolation of 1400 hours. Orientation of the roof is 30° West of South. The local Latitude is 45° and the roof angle 35° (inclination difference 10°). If your property is located in the US, go directly to US Insolation Charts.

• Hot Water Consumption and Storage Capacity

• Solar Insolation

• Orientation

• Inclination