I will compare some nominal power inputs to add perspective about the dead in the water forced air furnace.
I will compare a nominal 3Ton = 36,000 BTU/h (10.55kW) furnace+AC running at about 1200CFM with gas fuel input at 45,000 BTU/h to similar heat pump system outputs and electric resistance heat.
The central furnace fan is probably about 1/2 horsepower rating (372W) and has some design tolerance built in where the brake horsepower is less than this. The heating output at 80% efficiency is 36,000 BTU/h (10.55kW). This output is constant regardless of outside temperature. This could be run with a small inverter generator or possibly a robust battery system in the 20kWh range with appropriate solar.
Note that the heating input for this size of furnace can go up to ~155,000 BTU/h (45.4kW) with only the same amount of fan power needed in the form of electricity.
Looking through Mitsubishi literature, a 3ton hyper heat pump (SUZ-KA36NAHZ) at 17f can deliver 25400 BTU/h (7439 W) of heat output with an input of 2490 W. You will need strip heat to supplement this output to make up the difference (10.55kW - 7.439kW = 3.1kW of electric heat) So total power input is 3.1kW + 2.49kW = 5.6kW input for 10.55kW output. This might be short a few hundred watts as you still have to run the fan. This could be done with a larger portable generator.
Electric resistance heat would need the full 10,550 W to equal the output and now you need a relatively large fixed natural gas generator and transfer switch.
My personal opinion is that a heat pump system for normal operation with a natural gas or propane furnace as backup emergency heating is a good option to cover emergency situations as much as possible without adding an additional separate system like a wood burning heater or similar device.
I will compare a nominal 3Ton = 36,000 BTU/h (10.55kW) furnace+AC running at about 1200CFM with gas fuel input at 45,000 BTU/h to similar heat pump system outputs and electric resistance heat.
The central furnace fan is probably about 1/2 horsepower rating (372W) and has some design tolerance built in where the brake horsepower is less than this. The heating output at 80% efficiency is 36,000 BTU/h (10.55kW). This output is constant regardless of outside temperature. This could be run with a small inverter generator or possibly a robust battery system in the 20kWh range with appropriate solar.
Note that the heating input for this size of furnace can go up to ~155,000 BTU/h (45.4kW) with only the same amount of fan power needed in the form of electricity.
Looking through Mitsubishi literature, a 3ton hyper heat pump (SUZ-KA36NAHZ) at 17f can deliver 25400 BTU/h (7439 W) of heat output with an input of 2490 W. You will need strip heat to supplement this output to make up the difference (10.55kW - 7.439kW = 3.1kW of electric heat) So total power input is 3.1kW + 2.49kW = 5.6kW input for 10.55kW output. This might be short a few hundred watts as you still have to run the fan. This could be done with a larger portable generator.
http://mylinkdrive.com/USA/M_Series/R410A_Systems-1/Outdoor_...
Electric resistance heat would need the full 10,550 W to equal the output and now you need a relatively large fixed natural gas generator and transfer switch.
My personal opinion is that a heat pump system for normal operation with a natural gas or propane furnace as backup emergency heating is a good option to cover emergency situations as much as possible without adding an additional separate system like a wood burning heater or similar device.