What type of heat and how do you heat your water? Returning from the basement can be against codes. If you heat with gas or oil there is always the possibility to pull flue gassed through the water heater chimney or draft diverter if the return is in the same room as the furnace or there is insufficient combustion air in the space. Have a contractor check the pressure in the return duct. It may be possible to "redirect" where the air is being pulled from by blocking the basement return. Ideally, you want 60% of the return air to come from the high point in the system. Your description would indicate that is not happening. The only time you want to return from the basement is if you wife has cold feet in the winter and she is spending a lot of time in the basement. Good luck,

YOU MIGHT HAVE TO CHECK YOU BLOWER speed on your electric board. Your blower probably has at least 4 speeds. Maybe you are not getting enough pressure in your ducts to move the air on the longer runs. On you electronic board there will be a post marked heat and one of the blower wires or on that post. You will have another post marked cool and another blower wire will be on that. the other blower hot wires will be on post mark spare or park, and the are just there to store the unused wires. Your wiring diagram will tell you the different speeds. Later paulbm

I'm having a hard time visualizing a mobile home affixed to a walkout basement. Please explain. Better yet, post some pictures!

Charles Ross the builder: You can usually put your hand right into the fan intake and contact the moving squirrel cage. That would hurt. Blower door safety switches safeguard against the hazard. You can find blower door safety switches on furnaces and air handlers. You go on to say: But their use is not restricted to combustion appliances. If their function were strictly as some type of combustion safety device, they wouldn't be installed on air handlers. The only reference to a blower door switch actually being used was on a Water Furnace that is designed to work with a gas or oil fired boiler. You then trying to scramble and point to a part that is typically found on a gas fired appliance door switch because those appliances operate with 120v. Where as an Electric air handler operates at 240v. Why does an air handler need 240v to operate? let's not think. We're builders pretending to know something we don't. We have subs on speed dial to do these things. If they come up after the fact? Deny, deny, deny, twist words. Change the subject entirely. You think this is anything new for a builder? Uh, no. Charles, your claim is that the switch is there to protect your fingers from the big bad blower that isn't behind a squirrel cage. You want to claim the squirrel cage is the blower wheel. If the door switch is only about safety to the tech servicing the machine why then does the switch you show only going to cut half the power available on an Electric Air Handler? You said electric air handler / not water furnace. And you're still saying air handler, which is wrong as usual. PS: I am not a chemical engineer. Not pretending to be one. This is HVAC discussions... it only went into the chemical realm of things over the discussion of Carbon Monoxide CO vs Carbon Dioxide CO2. The difference from these two substances is WHAT? How they are WRITTEN: CO vs CO2 What is the difference between the two? 1 oxygen. Molecule, atom? What ever you want to call it I don't care. This is HVAC. CO vs CO2? one will kill you, the other won't. That is all I care about, preventing an untimely death. I am expected to know HVAC, not chemistry. Let's argue over molecules and atoms and the safety of a blower door switch that is missing on air handlers? If this switch is not missing? I am still waiting for you to show me an ELECTRIC AIR HANDLER that has a blower door swich. Let's make excuses and show a blower door switch (a part) that wasn't designed for what we claim. If anything this thread shows how much smoke a builder can blow and just keep blowing it for the sake of blowing smoke. What does that smoke contain? Better hope it's not CO