Heat Pump Savings Comparison
Annual operating cost savings of a hot water heat pump vs. a steam boiler and a hot water boiler
Annual Savings by Heat Source Temperature
Imperial UnitsBreakeven heat source temperature: 63.2°F vs. steam boiler, 76.1°F vs. hot water boiler. Above breakeven the heat pump is cheaper to run.
Heat Source
80°F
Heat Pump COP
3.87
Savings vs. Steam Boiler
$29,256/yr
Savings vs. Hot Water Boiler
$6,795/yr
Heat Drawn from Source
2.23 MMBtu/hr
Electricity In
0.77 MMBtu/hr
227 kW
Heat drawn from source + electricity in = 3.00 MMBtu/hr delivered to the process.
Boiler Operating Cost
| Steam Boiler | Hot Water Boiler | |
|---|---|---|
| Size (boiler HP) | 114.9 BHP | 99.6 BHP |
| Input | 3.85 MMBtu/hr | 3.33 MMBtu/hr |
| Output | 3.00 MMBtu/hr | 3.00 MMBtu/hr |
| Efficiency / COP | 78.0% | 90.0% |
| Annual Energy | 33,692 MMBtu | 29,200 MMBtu |
| Annual Cost | $168,462 | $146,000 |
Boilers sized on fuel input (heat load ÷ efficiency) at 33,475 Btu/hr per boiler horsepower. Conversions: 1 therm = 0.1 MMBtu, 1 MCF = 1.038 MMBtu, 1 MMBtu = 293.071 kWh = 1.055 GJ.
Heat Pump Savings
| Heat Pump + Steam Boiler | Heat Pump + Hot Water Boiler | |
|---|---|---|
| Heat Pump Output | 3.00 MMBtu/hr (100%) | 3.00 MMBtu/hr (100%) |
| Additional Heat from Boiler | 0.00 MMBtu/hr (0%) | 0.00 MMBtu/hr (0%) |
| Heat Pump Electricity Cost | $139,205 | $139,205 |
| Additional Boiler Fuel Cost | $0 | $0 |
| Total Annual Cost | $139,205 | $139,205 |
| Boiler Alone Annual Cost | $168,462 | $146,000 |
| Annual Savings | $29,256 | $6,795 |
Savings = boiler alone − (heat pump electricity + boiler fuel for any additional heat). Additional heat is needed only when the heat source can't support the full load. Heat pump COP = % of Carnot × TH / (TH − TC), absolute temperatures.
Heat Sink (Process)
MMBtu/hr
°F
Operating Schedule
hr
days
days
Annual Operating Hours8,760 hr
Energy Prices
$
$$/kWh
Spark Spread4.10
System Efficiencies
%
%
%