Question 1

How does a heat pump work?

Accepted Answer

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. 
https://static.wixstatic.com/media/435394_0a845c5538df4179aac91e663a2d3b1e~mv2.jpg
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(https://home.howstuffworks.com/home-improvement/heating-and-cooling/heat-pump.htm)

Question 2

Types of heat pump systems

Accepted Answer

Information on heat pump systems: https://www.energy.gov/energysaver/heat-pump-systems(https://www.energy.gov/energysaver/heat-pump-systems)
Types of systems
 • Geothermal heat pumps (https://www.energy.gov/energysaver/geothermal-heat-pumps)
 • Air-Source heat pumps (https://www.energy.gov/energysaver/air-source-heat-pumps)
 • Ductless, mini-split heat pumps (https://www.energy.gov/energysaver/ductless-mini-split-heat-pumps)
 • Absorption heat pumps (https://www.energy.gov/energysaver/absorption-heat-pumps)
 • Hydronic heat pumps (https://www.123zeroenergy.com/how-does-a-hydronic-air-source-heat-pump-work.html)

Question 3

Estimating home heating/cooling needs

Accepted Answer

The 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(https://www.ecomfort.com/stories/1439-What-Size-Mini-Split-Should-You-Buy.html)
 • BTU Calculator(https://www.calculator.net/btu-calculator.html)
 • Pioneer(https://www.pioneerminisplit.com/pages/hvac-calculator?gclid=Cj0KCQjwl8anBhCFARIsAKbbpySSQOfyEqAjtCB95uwDpUK041uRoQh8o-zVtGus6jWzddx1ZT5RvjwaAkCHEALw_wcB)
 • THS(https://www.totalhomesupply.com/heating-btu-calculator?gclid=Cj0KCQjwl8anBhCFARIsAKbbpyTJ7tGajJwgrnv6Q6B29k8AwUCuzNyF1c-znuD_Cb5QAz0WPQMIJnoaAkRZEALw_wcB)

Question 4

How do I determine the size of heat pump needed?

Accepted Answer

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)(chrome-extension://oemmndcbldboiebfnladdacbdfmadadm/https://www.xcelenergy.com/staticfiles/xe-responsive/Energy%20Solutions/Residential%20Solutions/23-11-205%20CO%20Res%20Rebate%20Summary%20Information%20Sheet.pdf).

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)(https://ashp.neep.org/#!/product_list/)

Question 5

How much does a heat pump system cost?

Accepted Answer

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 (https://www.forbes.com/home-improvement/hvac/heat-pump-installation-cost/)
 • This old House (https://www.thisoldhouse.com/heating-cooling/reviews/heat-pump-cost)
 • Bob Villa (https://www.bobvila.com/articles/heat-pump-cost/)

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 (https://www.energystar.gov/about/federal_tax_credits/electric_panel_upgrade))
 • Mechanical (modify ducting, running tranfer lines)
Tax credits and rebates

Question 6

How much does it cost to run a heat pump system?

Accepted Answer

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. 
https://static.wixstatic.com/media/6ef829_b2e646e1926e4444ae22af77a121923e~mv2.png

Efficiency: Coefficient of Performance COP=  (Heat out)/(Electric energy in)

Example COPs
https://static.wixstatic.com/media/6ef829_17c610e9cc364384884ff7af2c9b9726~mv2.png

https://static.wixstatic.com/media/6ef829_89b7b4c9c5b044138695bc122c373324~mv2.png

https://neep.org/sites/default/files/ColdClimateAir-SourceHeatPumpSpecificationProductListing-Updated11.30.18.xlsx(https://neep.org/sites/default/files/ColdClimateAir-SourceHeatPumpSpecificationProductListing-Updated11.30.18.xlsx)

Question 7

Tax credits and rebates

Accepted Answer

Typically require certification.
Links: https://loveelectric.org/news/building-electrification-rebates-for-2023/(https://loveelectric.org/news/building-electrification-rebates-for-2023/)
https://www.energystar.gov/about/federal_tax_credits/air_source_heat_pumps(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
• Up to $1,500 tax credit available immediately: https://energyoffice.colorado.gov/hptc (https://energyoffice.colorado.gov/hptc)
Utilities and local
•Xcel Rebates: $2,250/ton, additional income qualified rebates
•Rebates for all utilities: https://loveelectric.org/rebates/(https://loveelectric.org/rebates/)
•Denver Rebates: up to $3,500: https://denvergov.org/Government/Agencies-Departments-Offices/Agencies-Departments-Offices-Directory/Climate-Action-Sustainability-and-Resiliency/Cutting-Denvers-Carbon-Pollution/Electrifying-Denvers-Homes/Resources-for-Home-and-Townhouse-Owners/Heat-Pump-Rebates (https://denvergov.org/Government/Agencies-Departments-Offices/Agencies-Departments-Offices-Directory/Climate-Action-Sustainability-and-Resiliency/Cutting-Denvers-Carbon-Pollution/Electrifying-Denvers-Homes/Resources-for-Home-and-Townhouse-Owners/Heat-Pump-Rebates)

•Some local government and utility credits https://loveelectric.org/new-homes/ (https://loveelectric.org/new-homes/)scroll to ”Tax Credits and Rebates”

Question 8

Steps to install your system

Accepted Answer

• Improve the insulation on existing home. This can improve the performance (https://www.energystar.gov/products/ask-the-experts/improved-home-insulation-helps-a-heat-pump-perform-better)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)(https://www.energystar.gov/about/federal_tax_credits/electric_panel_upgrade)
 • 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:

https://static.wixstatic.com/media/6ef829_862157dc32454ee693f5541afaff2079~mv2.png

• 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.

Question 9

Environmental impact

Accepted Answer

•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)(https://www.c2es.org/content/home-energy-use/)

Question 10

Consumer protection

Accepted Answer

No one should feel they are being taken advantage of while pursuing clean energy. At the federal level, you can contact the Federal Trade Commission (https://reportfraud.ftc.gov/)t(https://reportfraud.ftc.gov/)o 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 (https://www.usa.gov/state-consumer)within your state or territory to see how they can help, too.

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