HPWH System Design Examples
System sizing analysis was based on Ecosizer with the following assumptions:
Cold water supply temp = 55F, Hot water supply temp = 125F, Storage temp = 135F
Peak gallons per person per day = 25, Recirculation heat loss = 100w/dwelling unit
Average number of people per dwelling unit = 2
Use One AO Smith CHP-120 HPWH
Heating capacity: 42 kBtu/h Heat pump and 41 kBtu/h (12 kW) electric resistance
Number of people to be served: 30 - 48
Number of dwelling units to be served: 15 - 24
Total Storage: 318 Gallons
Storage connected to compressors: 119 Gallons
Primary storage: 119 Gallons
Temperature maintenance storage: 80 Gallons
System footprint: 9 X 3 ft
Using a temperature maintenance storage to
increase storage capacity and enhance recirculation controls,
this system minimizes electric resistance heating.
Total Storage: 238 Gallons
Storage connected to compressors: 119 Gallons
Primary storage: 119 Gallons
Temperature maintenance storage: none
System footprint: 6.5 X 3 ft
This system has a smaller footprint and
uses advanced recirculation controls to
reduce electric resistance heating.
Use Two SANCO2 HPWHs and
One Tankless Electric Resistance Water Heater (ERWH)
Heating capacity: 30.8 kBtu/h Heat pump and 5.1 kBtu/h (1.5 kW) electric resistance
Number of people to be served: 16 - 32
Number of dwelling units to be served: 8 - 16
Total Storage: 252 Gallons
Storage connected to compressors: 83 Gallons
Primary storage: 119 Gallons
Temperature maintenance storage: 50 Gallons
System footprint: 8 X 3 ft (not including compressors)
This low-power system achieves high-performance operation
by using advanced recirculation controls to
minimize or avoid electric resistance heating.
Total Storage: 202 Gallons
Storage connected to compressors: 83 Gallons
Primary storage: 119 Gallons
Temperature maintenance storage: none
System footprint: 6 X 3 ft (not including compressors)
This low-power system has a smaller footprint.
Electric resistance heating is reduced
by advanced recirculation controls.
Use One SANCO2 HPWH and
an Optional Tankless Electric Resistance Water Heater
Heating capacity: 15.4 kBtu/h Heat pump and 2.7 kBtu/h (0.8 kW) electric resistance
Number of people to be served: up to 16
Total Storage: 252 Gallons
Storage connected to compressors: 83 Gallons
Primary storage: 119 Gallons
Temperature maintenance storage: 50 Gallons
System footprint: 8 X 3 ft
With advanced recirculation controls
and the temperature maintenance tank,
the electric resistance heater is optional.
Total Storage: 163 Gallons
Storage connected to compressors: 83 Gallons
Primary storage: 80 Gallons
Temperature maintenance storage: none
System footprint: 6 X 3 ft
This small-footprint system is suitable for buildings with
relatively constant hot water demand. Electric resistance heating
is reduced by advanced recirculation controls.
Use One Integrated 50-gallon HPWH
Heating capacity: 4.2 kBtu/h Heat pump and 15 kBtu/h (4.5 kW) electric resistance
Number of people to be served: up to 8
Total Storage: 169 Gallons
HPWH storage: 50 Gallons
Primary storage: 119 Gallons
Temperature maintenance storage: none
System footprint: 6 X 3 ft
With relatively large storage capacity,
this system can meet large peak demand
while maximizing heat pump operational efficiency.
Total Storage: 130 Gallons
HPWH storage: 50 Gallons
Primary storage: 80 Gallons
Temperature maintenance storage: none
System footprint: 5 X 2.5 ft
This system maximizes heat pump operation to
meet hot water demand and use advanced recirculation control to
reduce electric resistance heating, .
