A Parametric Analysis of Residential Water Heaters

Gas storage, gas tankless, condensing, electric storage, heat pump, and solar water heaters were simulated in several different climates across the US installed in both conditioned and unconditioned space and subjected to several different draw profiles. While many preexisting models were used, new models of condensing and heat pump water heaters were created specifically for this work to look at the majority of residential water heaters available on the market. The heat pump water heater model was extensively validated against both field test and lab test data and found to predict the performance of these units well in all of the situations examined. The condensing water heater model was compared to lab test data and found to provide a reasonable agreement with the measured data. A domestic hot water distribution system model was also created, validated, and used to examine the difference in distribution losses between heat pump water heaters and electric storage water heaters. Annual simulations looked at both the energy savings potential and economics of these technologies. Heat pump water heaters were significant winners in both cost and energy savings for electric water heater and proved to be a cost effective replacement for electric storage water heaters even before incentives were considered in many cases. For gas water heaters, all technologies were able to save some energy with solar water heaters providing the most significant savings. However, none of the gas water heating options here proved to be cost effective without incentives. With incentives there were several situations where these water heaters were cost effective