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How does a heat pump work?A heat pump moves heat from one source to another instead of generating heat. In the winter a heat pump moves heat from the outside of your house into your house and in the summer it moves heat from inside your house to the outside. The outside source or sink of heat can be the air or ground. For air-sourced systems, heat is moved by compressing and expanding air and transferring it with a heat transfer fluid. Heat pump systems contain: Compressors Transfer lines Heat exchangers https://home.howstuffworks.com/home-improvement/heating-and-cooling/heat-pump.htm
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Types of heat pump systemsInformation on heat pump systems: https://www.energy.gov/energysaver/heat-pump-systems Types of systems Geothermal heat pumps Air-Source heat pumps Ductless, mini-split heat pumps Absorption heat pumps Hydronic heat pumps
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Estimating home heating/cooling needsThe following links provide calculators to estimate the heating/cooling needs for your home. These calculators provide estimates of the heating/cooling for each room in BTU/h. These estimates can be used to size the heat pump as discussed in the next question. Ecomfort BTU Calculator Pioneer THS
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How do I determine the size of heat pump needed?Use the heating/cooling requirements for your house to select appropriate heat pump(s). You can determine the heating/cooling requirements for each room in your house using the links in the previous question. This will give you values of heating/cooling requirements in BTU/h. Ducted systems: If you have a ducted system (such as a central air heating system), you can replace the existing furnace with a heat pump that will service all of the rooms connected to the ducting. The heating requirement will be the sum of all of the rooms that are connected. Ducted systems contain a outdoor compressor and a heat exchanger that is connected to the ducts. Ductless system (mini-splits): For ductless systems, there is a head (heat exchanger) in each room that is being heated/cooled. The heating/cooling output of the head should be slightly larger than the calculated requirement for that room. For ductless systems, the outdoor compressor can often service more than one head. The heating/cooling output of the compressor should be larger than the output of all of the heads that it services. The output of the compressors and heads are typically quoted in 1,000 BTU/h. Sometimes they are quoted in "tons". One ton is equivalent to 12,000 BTU/h. For air-sourced heat pumps, it is important to select a heat pump that can operate at temperatures prevalent during the winter. In Colorado, because of cold winters, you should only purchase Cold Climate heat pumps. Xcel requires a Coefficient of Performance (COP) of greater than 1.75 at 5°F (see this link). The COP is the amount of heating (or cooling) provided divided by the electrical energy input. COPs can be as high as 5-6, which is why heat pumps are so efficient. The COPs for most heat pumps can be found on a website hosted by the North East Energy Partnership (click here)
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How much does a heat pump system cost?With installation, cost can be $3,000 to over $15,000 for air sourced heat pump systems without credits or rebates. The following links discuss costs: Forbes This old House Bob Villa Considerations Equipment Compressor (s), heat exchangers Size (BTU requirements, air flow 1 – 5 ton) Efficiency (COP, SEER, HPSF) Cold weather capable? Brand Installation Electrical (Run wires, modify service – tax credits are available for panel upgrades ) Mechanical (modify ducting, running tranfer lines) Tax credits and rebates
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How much does it cost to run a heat pump system?Heat pumps can be cheaper than propane and in some cases cheaper than natural gas for heating. This table shows the cost of different heating systems (combustion of Propane and Natural Gas and Electric Resistance) compared to heat pumps with coefficient of performance (COP) of 1 to 4. With COP greater than 1, heat pumps are cheaper than propane. With COP greater than 2 heat pumps are cheaper than natural gas. The graphs below show the COP for some example heat pumps as a function of outdoor temperature. Under most conditions, these heat pumps have COP greater than 1 and at most temperatures greater than 2. Efficiency: Coefficient of Performance COP= (Heat out)/(Electric energy in) Example COPs https://neep.org/sites/default/files/ColdClimateAir-SourceHeatPumpSpecificationProductListing-Updated11.30.18.xlsx
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Tax credits and rebatesTypically require certification. Links: https://loveelectric.org/news/building-electrification-rebates-for-2023/ https://www.energystar.gov/about/federal_tax_credits/air_source_heat_pumps Federal •Inflation Reduction Act (IRA), heat pumps and heat pump water heaters (HPWHs) are eligible for a 30% tax credit, 2023 •Up to a limit of $2,000 per taxpayer State Tax Incentives •12.9% state tax credit •Exempt from the state sales tax, which is 2.9%. •New Homes: 12.9% state tax credit Utilities and local •Xcel and Tri State •Rebates for all utilities: https://loveelectric.org/rebates/ •Denver: Rebates •Some local government and utility credits https://loveelectric.org/new-homes/ scroll to ”Tax Credits and Rebates” Summary for Existing Homes
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Steps to install your systemImprove the insulation on existing home. This can improve the performance of your heat pump system and reduce cost. Identify type of heat pump system. Is this for a new home or a replacement of existing HVAC system? What type of existing system? Forced air, mini-splits, hydronic. Select a contractor. Get multiple bids. You should not have to pay for bids. Electrical service. Most heat pumps require 220 V circuits. Make sure that you have room on your panel. You may have to upgrade you panel (tax credits are available for this) Back up heating. You may need to have a back up heating system for vey cold days. These can be electrical resistive heating systems. Remember, 0nly a small fraction of of time over the year will be a very cold temperatures. This plot shows a distribution of the hourly temperatures at Denver International Airport: Net zero. If you are interested in a net zero home, you can use home solar PV or community solar PV to provide the power for your heat pump.
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Environmental impact•Potential reduction of impact: “Home heating and cooling is responsible for roughly 441 million tons of carbon dioxide annually.” •Average US household produces 3 – 4 tons/y of CO2 from heating and cooling (https://www.c2es.org/content/home-energy-use/#:~:text=On%20space%20heating%20alone%2C%20Americans,tons%20of%20carbon%20dioxide%20annually)
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Consumer protectionNo one should feel they are being taken advantage of while pursuing clean energy. At the federal level, you can contact the Federal Trade Commission to report fraud, scams, and bad business practices. At the state level, laws vary depending on where you live. You can contact one of the consumer protection offices within your state or territory to see how they can help, too.
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