An all-electric pathway uses the geothermal heat pump as the primary system with properly sized and staged electric auxiliary or emergency heat where the design requires it. A dual-fuel pathway coordinates the heat pump with a combustion heat source. The better fit depends on delivered geothermal capacity, peak load, electrical service, available fuel, controls, venting, homeowner priorities and current program rules.
SIDE-BY-SIDE
Two ways to cover peak and emergency conditions.
| Decision area | All-electric | Dual-fuel |
|---|---|---|
| Backup source | Staged electric auxiliary or emergency heat. | A coordinated combustion heating source. |
| Electrical review | Service, panel, feeder, breaker and auxiliary-heat demand are central design checks. | The heat pump still needs electrical review; combustion equipment, blower and controls add their own requirements. |
| Fuel and venting | No combustion fuel or venting for the heating system. | Fuel supply, venting, combustion air, condensate and safety controls require verification. |
| Control sequence | Stages compressor and auxiliary heat according to load, recovery and emergency operation. | Coordinates compressor operation, fuel switchover or staging, lockouts and equipment safeties. |
| Outage planning | Large electric resistance loads can materially affect generator or battery design. | May reduce electric backup demand, but the full operating sequence and fuel availability still matter. |
| Program fit | Must be checked against current approved equipment and program rules. | Must be checked separately; retaining or adding combustion backup may change eligibility and scope. |
ONE ENERGY PATHWAY
All-electric geothermal
The geothermal compressor carries the normal heating load while controls add verified electric heat only when the design calls for it—such as peak weather, recovery or emergency operation.
- No combustion heating appliance, fuel piping or flue in the system pathway
- A single electric energy pathway can simplify some operating decisions
- Compatible with staged control strategies when equipment and electrical capacity support them
- Electrical service and panel capacity
- Auxiliary heater size and staging
- Thermostat configuration and lockouts
- Peak demand and outage expectations
COORDINATED HEAT SOURCES
Dual-fuel geothermal
The heat pump and a combustion heat source operate under a defined sequence. That may involve retaining suitable equipment or designing a new matched pathway; it is not simply leaving the old furnace in place without review.
- Can preserve a fuel-based peak or emergency strategy where appropriate
- May reduce reliance on large electric resistance stages
- Can support homeowner resilience or operating preferences when properly controlled
- Equipment compatibility and airflow path
- Fuel supply, venting and combustion safety
- Switchover, lockout and staging logic
- Current program eligibility and installation scope
OPERATING SEQUENCE
The thermostat label is not the control design.
The field setup must define when compressor stages change, when auxiliary or fuel heat can operate, how outdoor or entering-water conditions affect the sequence, and what “emergency heat” actually does. Communicating equipment, zoning and retained equipment can add compatibility requirements.
- Document normal, recovery, peak and emergency operating modes.
- Confirm blower airflow at every active stage.
- Prevent unintended simultaneous operation where the design prohibits it.
- Set and commission temperature, time and equipment lockouts.
- Leave the homeowner with a clear explanation of normal alerts and emergency operation.
OUTAGE PLANNING
A battery or generator is a separate load study.
Heat-pump compressor starting, blower and pump loads, auxiliary heat, retained combustion equipment and desired runtime all affect a resilience plan. A battery or generator should not be described as “whole-home” based only on the geothermal unit’s nominal tonnage.
Heating at reduced capacity, full design heating, domestic water, well pumps and electric auxiliary heat create very different generator, battery and load-management requirements.
CURRENT LITE WORKFLOW
The online choice records a preference—not a final design.
The quote tool carries all-electric, dual-fuel or “compare both” into the ServiceTitan project summary. It does not add electrical circuits, service upgrades, combustion work or a backup-heat price. Those items require the site walk, verified load, exact equipment and current program review.
Start the preliminary home review →SITE-WALK CHECKLIST
What turns the preference into a final pathway.
- Verify the heating and cooling loads and selected equipment performance.
- Establish the intended geothermal balance point and peak-load strategy.
- Inspect the electrical service, panel, feeder path and available capacity.
- Inspect retained fuel equipment, fuel supply, venting and combustion safety where applicable.
- Measure airflow and static pressure at the required operating stages.
- Define controls, lockouts, emergency operation and homeowner handoff.
- Confirm current equipment, installation and payment-program eligibility.