Heat pump size & savings calculator
A quick, honest ballpark for Palo Alto homes: what size heat pump you might need, what heating and cooling could cost each year, and what CPAU pays toward the switch.
Call 650-460-3483This free calculator from ComfortFlow HVAC Palo Alto gives a ballpark heat pump size in tons and compares yearly heating and cooling costs for a gas furnace and air conditioner versus a heat pump, using Palo Alto climate data (about 2,584 heating and 452 cooling degree days a year) and City of Palo Alto Utilities rates you can adjust. It is an estimate, not a Manual J load calculation.
Reviewed and updated by the ComfortFlow HVAC Palo Alto team
Try it with your home
How the calculator works
We built this tool to give Palo Alto homeowners a realistic starting point before they talk to anyone. Here is exactly what it does, so you can judge the numbers yourself.
| Input or assumption | What we use |
|---|---|
| Climate | Palo Alto station normals: about 2,584 heating degree days and 452 cooling degree days a year (base 65°F) |
| Heat loss by home era | Typical heat-loss factors for Palo Alto housing eras, from pre-1940 homes to 2000s builds; Eichlers get a higher factor for glass walls and thin roofs |
| Size estimate | Square feet per ton by era, shown as a half-ton range |
| Electricity price | Default $0.22 per kWh, close to CPAU’s 2026 winter off-peak E-1 rate; change it to match your bill |
| Gas price | Default $2.50 per therm as an example; CPAU’s commodity price changes monthly, so enter your own |
| Efficiency | Gas furnace AFUE, old AC SEER, and new heat pump HSPF2 and SEER2 you choose |
| Rebate | CPAU Heat Pump HVAC rebate: $2,500, or $5,000 income-eligible, when replacing gas heat |
What it does not do
A calculator cannot see your windows, insulation, ducts, air leaks or electrical panel. That is what our in-home Manual J is for, and it often changes the answer by a half ton or more. Use this tool to get oriented, then request a visit or call 650-460-3483 for real numbers.
Sources
- Golden Gate Weather Services: Palo Alto climate (station 046646)
- City of Palo Alto Utilities: Residential electric rate schedule E-1 (TOU)
- City of Palo Alto Utilities: Residential gas rate schedule G-1
- U.S. Department of Energy: 2023 central air conditioner and heat pump standards FAQ
- City of Palo Alto: Rebate Hub
Calculator
questions.
How the numbers work, from the ComfortFlow HVAC Palo Alto team.
How accurate is this heat pump calculator?
It is a ballpark. The size estimate uses square feet per ton by home era, and the cost estimate uses Palo Alto degree days and the rates you enter. Real loads depend on windows, insulation, air leakage and ducts, which only an in-home Manual J load calculation can measure. In our experience a Manual J can shift the right size by a half ton or more, so treat the result as a starting point for a conversation, not a final answer.
Why does the calculator ask when my home was built?
Building era is the best single predictor of heat loss in Palo Alto. Pre-1940 homes in Professorville and Old Palo Alto often have little wall insulation, post-war homes vary widely, Eichlers have large single-pane or older glass walls and thin roofs, and homes built after 2000 meet much tighter energy codes. The calculator adjusts both the size range and the yearly heating estimate for each era.
What electricity and gas prices should I enter?
Use the numbers on your City of Palo Alto Utilities bill if you have them. The default electricity price of $0.22 per kWh is close to CPAU’s 2026 winter off-peak residential time-of-use rate, which is when heat pumps do most of their work. Gas prices change monthly with the commodity market, so the $2.50 per therm default is only an example. Changing these two numbers has the biggest effect on the savings result.
Let’s make home
feel better.
Tell ComfortFlow HVAC Palo Alto what’s happening with your heating or cooling, and we’ll start with the right questions. Serving Palo Alto, Menlo Park, Mountain View, Los Altos, Stanford and the Peninsula.
Palo Alto, CA 94306
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