Heat Pump or Gas Furnace: Compare Operating Costs Using Your Own Bills

Compare the same service

Begin with the rooms heated, desired temperatures, occupied hours and existing cooling use. A whole-house furnace and one portable heater serving a single room do not deliver the same service. Likewise, a new heat pump providing summer cooling adds a benefit and potentially a use that the old heating-only system did not have.

Write those differences down before comparing bills. A lower bill can reflect less heating rather than better equipment, while a higher bill can reflect more comfort. Neither observation is useless, but neither proves the operating-cost difference on its own.

Separate household consumption from heating

Collect bills across a representative period and identify other major changes: vehicle charging, occupants, water heating, solar production or working from home. Ask the HVAC professional what information supports a heating-energy estimate and what remains uncertain.

Your gas bill may include cooking and water heating. Your electric bill includes more than the proposed heat pump. Comparing the entire old gas bill with the entire new electric bill would mix unrelated uses. Keep a worksheet that distinguishes measured totals, estimated heating portions and assumptions.

Use the tariff that will actually apply

Check your current rate details and ask whether the planned equipment affects your available plan or allowance. Include the relevant timing of electricity use instead of relying on one headline price. PG&E Building Electrification notes changes to PG&E billing beginning in March 2026, another reason that an old Reddit calculation should not become your current forecast.

If you have a community-choice electricity provider, solar or storage, make sure the comparison reflects your own billing arrangement. Do not assume a neighbor’s low net bill can be reproduced by adding a heat pump to a different house.

Request scenarios rather than one savings promise

Ask for a documented model with the selected equipment, efficiency assumptions, expected use and energy prices. Request a lower-use and higher-use case if uncertainty is material. A model should show which input changes the result, not merely print an attractive annual savings number.

A hypothetical homeowner comparing continued gas heating with electric heating might find the decision sensitive to winter usage. That suggests looking harder at comfort settings, building condition and equipment selection. It does not justify claiming one fuel will always be cheaper throughout the Bay Area.

Keep installation economics separate

Compare installed scope, ongoing energy costs and nonfinancial benefits in separate columns. Cooling, comfort, equipment condition and a planned remodel can matter even where a modeled bill reduction is small. Conversely, favorable operating costs do not erase a large installation expense.

Ask providers to identify incentives separately and confirm current eligibility before including them in your budget. This guide does not assume any tax credit or rebate remains available. Save the model and review actual consumption after installation against its assumptions; that is more informative than comparing your household with a forum commenter.

What to request in a transparent comparison worksheet

Ask the provider to show a baseline column and a proposed-system column. Both should describe the same occupied space and comfort goal. Below them, list the energy-price assumptions, equipment assumptions and annual-use estimate. Mark each input as measured, supplied by the provider or estimated. That labeling is often more informative than a very precise-looking savings total.

Keep installation cost outside the energy calculation. Show it in a separate decision table alongside equipment condition, desired cooling and disruption. If incentives are included, identify the specific program and confirmed eligibility rather than subtracting an unverified amount. A favorable annual model does not establish how quickly a household will recover a purchase cost.

For a hypothetical house with new cooling as part of the project, prepare two comparisons: heating service alone and the household’s intended total use after installation. Otherwise, the added summer comfort can make the proposed system look unfairly expensive or disappear from the forecast altogether.

Ask which assumptions would materially reverse the conclusion. If the answer is winter consumption, request a realistic range. If it is the rate plan, verify the actual plan. If it is an equipment-performance claim, ask for the basis and whether installation conditions are reflected. Do not fill an evidence gap with another household’s monthly bill.

After installation, retain the worksheet and compare actual use over a suitable period, noting weather and household changes. A mismatch becomes a question to investigate: different usage, different rates, a modeling error or a system issue. It is not automatically evidence that the technology itself is unsuitable. The original assumptions give that investigation somewhere concrete to begin.