A variable or multi speed furnace monitors the temperature of your home and then adjusts the speed of the blower motor sometimes referred to as an ecm motor in very small increments.
Single stage furnace with ecm motor.
With a 40k low stage the 2 stage will not be a reduction in comfort or gas efficiency over a single stage furnace.
I m sticking with single stage as all the contractors recommended them.
So if those are your 2 options at the same price i d go with the 60k 2 stage.
Instead either use a.
Keeprite bryant and carrier offer single stage with ecm motors.
Output of the motor can be adjusted by signals from a controller or permanently programmed to advance through a range of speeds during each on cycle of the furnace.
Variable speeds unlike an on off psc motor a furnace ecm motor can operate at a range of outputs between zero and 100 percent.
This increased precision results in a home that is more consistently heated both in different areas of the home and over time.
And the ecm motor will have greater electrical efficiency.