Return air duct for heater

Has anyone put a return air duct from the grill in the steps to the furnace to make the heater more efficient like what is installed in ahome. Please advise and or show pictures

It looks like this 3950FB has one.

I really don't think that's a return. In our coach a BC 4010RD, we have a vent in the stairs but it is just open to the area behind the basement wall. I figured it was to allow coach heat into that area for the plumbing, since the "heated underbelly" duct goes from the furnace down below into the lower area under the floor where tank valves are and such.

We have a heater return above the pantry/cabinetry in the kitchen.


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I think that most people don't realize that the duct in the stairs is an open vent to the basement and when it is cold out and you open one of the compartment doors while the heater is running you are now allowing the heater which is in this open area to suck cold air from outside, heat it and put it in the rig. If you look at a heater system on the house it recirculates the heat thru the house to make the unit more efficient. Also when you open the compartment doors you are allowing cold air to enter the rig thru the basement and thru this vent in the stairs as it is not a sealed return to the heater. You also have the problem of letting in hot air thru this area in the summer causing the A/C to work more. I was looking to see if any one had built a return air from this grill directly to the heater. Thanks for the input so far.

It is the return but it is just not ducted. I guess that was to point of the thread.