Efficient heating of sanitary water with heat pump

Abstract

This work presents a thermal and economical assessment about replacing the conventional household water heater (electrical, 100 % efficiency) by a modern heat pump water heater, which efficiency is proportional to the outdoor temperature, but about three and five times higher than the previous one. Thus, the efficiency calculated for capitals of Latin-American countries has obtained average values ranging from 298 % to 434 %. However, the payback period obtained is also related to the electricity tariff and the temperature of the cold-water grid, which varies from 0.064 US$/kWh in Paraguay to 0.233 US$/kWh in Costa Rica, and from 10 °C (La Paz) to 26.8 °C (Costa Rica). Thus, a ranking of payback period (replacing/new installation) was performed for an average consumption of a five-person family, obtaining values ranging from 2.4/1.4 years (Montevideo) to 10.5/6.1 years (Asunción), and also it was calculated the energy annual saving obtaining from 1,436 kWh (Costa Rica) to 2,660 kWh (La Paz). Thus, we have found great potential for household energy saving in Latin-American countries by substituting the conventional water heater by a modern heat pump.

Keywords:

Thermal Modeling, Household Electric, Water Heaters, Heat Pump for Wateer Heating, Energy Efficiency, Economic Analysis.