Keeprite bryant and carrier offer single stage with ecm motors.
Single stage furnace with ecm motor.
This increased precision results in a home that is more consistently heated both in different areas of the home and over time.
When a furnace or air handler with an ecm is installed on a good duct coil and filtration system with static pressures within proper design parameters it can perform flawlessly.
I m sticking with single stage as all the contractors recommended them.
And the ecm motor will have greater electrical efficiency.
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.
Variable speeds unlike an on off psc motor a furnace ecm motor can operate at a range of outputs between zero and 100 percent.
Instead either use a.
Be sure to not use the built in staging timer if you go that route.
With a 40k low stage the 2 stage will not be a reduction in comfort or gas efficiency over a single stage furnace.