How large living space is your basement? A basement needs a properly placed return (s) for airflow and improved comfort.. are there dampers on your supply duct to basement?

IMO

Is the furnace located in the basement? If it is then the basement vents should be getting the most air flow. You shouldn't need to add "curved metal bar" to push more air into the basement duct work. Something may be blocking the flow of air. Perhaps you have a unconnected duct or as Tigerdunes suggests a damper needs to be opened.

You have to be careful adding a return in a basement if the furnace is nearby. Trying running the furnace with basement doors open and closed. If you see no difference then I question the value of adding a return.

Hey all! Thanks so much for the responses. I've made this post in another place and seem to get different answers from different techs.

To answer your questions above:

Size of basement, estimating 10 x 30 feet.

The furnace is located in the basement. The basement trunk is not on the mainline of the home. The idea in option #1 is to divert some of that (abundant) air into the trunk.

In favor of option #1 (Adding a metal bar to divert some of the air into the basement trunk)

* Having a return down there isn't going to generate more heat. You seem to have a velocity issue that can be mitigated with turning vanes in the ductwork.

* If your basement is totally isolated meaning there's no open doors or stairwells to the Upper Floor then that makes some sense. A return would definitely help get the cold air out of there and increase circulation of the room, but it will not increase the velocity of the supply Air if the ductwork is not located at the Appliance in a favorable location.

* You just don't seem to be introducing enough heat because your velocity is poor. I would focus on just getting more heat into that area.

* You can still always add a return if option one does not work. I think there's a greater chance of option one working then option two working.

* If the basement is open to the rest of the house, then you could have an issue where the least resistant path for the air is to rise into the upper floors rather than being directed into the basement... so company 1 could be right...

In favor of option #2 (Adding a return in the basement)

* Adding hot air to a room without a return will not heat up the room in the way you are seeking.

* You need dampers and cold air return.

* If the air can't get back to the unit for conditioning (heat/cool), then you won't have service to that zone...

Thanks again for any other insight you can offer. I may end up getting a 3rd opinion/estimate...

If the furnace sits in the room you're trying to heat (the basement is wide open / unfinished) it's not a good idea to put a 'open' vented return near the furnace. In some situations the return may rob the furnace of combustion air / in the event of that causes the furnace to produce carbon monoxide due to improper burning of the gas. So if this is what you have, it changes things considerably. The furnace needs a dedicated combustion air stream to work properly.

If the above statements are correct forget doing what you are thinking here....

Personally choice 1 or 2: both of them have problems to contend with, option 1 has more problems than choice 2.

It's not that you can't heat the room with option one, but that heat you supply to it is going to replace the air in that room. Where is that air going to go?

This is science, not magic.

If you need to visualize it: take two cups a small cup and a larger cup. Fill the larger and smaller cup to the brim with your favorite liquid. Pretend the liquid is 'air'.

Now try to fit the contents of the larger cup into the small cup without spilling it. (If you're a magician you could probably do it.)

So under this premise: by putting a return in the room you are trying to heat... you dictate where the air in the room is going to go... (assuming it is safe to do this).

Control: thermostat is on upper level, when it reaches set point the basement may still be too cold. Crank the thermostat, now the basement gets too hot. -- because the furnace is so close to the area getting heat.

HVAC is a 'cause and effect'. You do one thing and it causes problems somewhere else. A solution looks at the whole problem, unfortunately for you this adds more expense. You're looking for comfort. What does that truly mean to you? (everyone has their own definition of what comfort is.)

Does the above mean you can't heat or cool a room without a dedicated return: no, that's not what it means. What it means is you may still be uncomfortable. What is your reason for doing this? uncomfortable. capeesh?

Can you post a photo of the basement trunk line? I would like to understand why air refuses to flow into it.