I have a finished room in my basement with a drop ceiling where the heat vent is. Another vent near the floor I assume is the return. This room is cold and no air comes out of ceiling vent when furnace is cranking. Traced the ducts back to the furnace and appears both are attached to the same trunk line which I believe is the supply. Does this cancel each other out? Otherwise I would think this room would be toasty with 2 supply ducts. Shouldn't one of these be attached to the return? Thanks

If this is an updraft heater, most common, the main supply duct should be at the top and your heater vents should come from there. No, the 2 ducts do not cancel each other. A return should be placed somewhere near the bottom of the wall and go into the heater on the return side, at the bottom. You can also buy return grills that accept small filters. Make sure you don't have dampers at the point where the supply line is connected. Look for a small threaded shaft or handle. The threaded shaft or handle should be parallel to the air flow.

The supply duct is coming off the main, through the ceiling, into the finished room. The return vent is at the bottom of the wall but duct goes upward and is attached to the main, right next to the supply duct. I do not see any dampers but, for the most part, joints are not taped or sealed in any way. Could this be why there is no heat entering the room? By cancelling each other out I meant, if the return is not going to the heater on the return side, could this diminish the heat supply? Otherwise, I would think both vents would be providing heat.
BTW, do I know you? I'm in MA and my brother lives in Woodstock.

From your description, I'm a little confused. If both of the ducts are coming off the same line, they are either both supply or return. Turn the fan on and hold a tissue in front of the vent. If they are sucked in, both are returns. That close to a heater, you would have to see a lot of pressure. Are you sure the attachment collar is through the duct? Some of the new takeoffs are sealed on with double sided tape and then the duct is cut. Is this a metal duct or fiberglass ductboard? Can you post a picture? I don't know if you know me. What's your brothers last name? Brian

I have metal ducts and I'm now sure they are both on the supply line. Without removing them, yet, I can't be sure the collar is through the duct but logic says... I will try to post a picture. If both are on the supply, shouldn't this room be toasty?

Is this ductwork insulated? If you are getting no air flow, as your answer suggests, they are rerurns or not open. Therefore, the room would be cold. Try the tissue teast and get back. We'll get you toasty!

I hope this works; http://cid-5bf93807daec6498.skydrive.live.com/redir.aspx?page=play&resid=5BF93807DAEC6498!109

I hope this works, copy & paste this link for pictures;
http://cid-5bf93807daec6498.skydrive.live.com/redir.aspx?page=play&resid=5BF93807DAEC6498!109

They look like they are coming out of the supply side but are not insulated. Maybe you have a counterflow heater and the person who hooked them up thought that was the supply. Have you tried the tissue paper test? Another test is to light a candle, let it burn and then while holding it near the vent opening, blow out the candle and move it to the vent. Where does the smoke go? Do these tests and get back to me. We'll figure this out yet.

I agree, they are both coming from the supply side! I did the tissue and candle test and the vent, on the wall near the floor, does have heat coming out of it.(4x10 duct on left, 1st pic) But the ceiling vent has nothing, the smoke went sideways and tissue didn't move.

I would remove the boot at the duct and see what's what. That take off is right next to the fan and should have plenty of air. In addition, you should insulate the ducts. However, depending on the size of the room, I would have a rerurn located at the bottom. This installation is very poor design.

Thanks! When I redo the return, can I attach it to the vertical duct going into the furnace or keep it on the horizontal trunk line above? If I can add to the vertical return air duct, how far away from return air plenum should it be?

The return duct may be attached along the return plenum. That's the part that connects to the filter assembly. I really want to know why heat is not coming out of both ducts!!

Well, I can't answer why heat wasn't coming from both ducts but I redid the ducts; take-off on left is now more direct to ceiling vent and I added a new take-off to return. This new take-off connects to the return vent low on wall, added a vertical duct at a 90o angle and then a 45o angle to attach to return just below the return trunk line. It felt it was too close to the plenum to go low (only @ 2-3 ft).
The return is sucking in air and there is heat coming from the ceiling.
I believe without the vacuum effect of the return, it wasn't pulling the heat from the supply duct. I could be wrong though. Now I just need to add some insulation and hope it stays warm.
Thanks for your help

Glad you got some heat going, congtatulations on your DIY skills. There is a direct response to air flow and no returns. You can only pressurize so much before air will bypass and go to an area of lower resistance. So by installing a return, it drops the static pressure in the room and more air will flow out.

You can "thank me" by clicking on the green thumb "is this helpful". Feel free to post any other Home and Garden question you may have and we'll try to help! Brian

Any idea how I can move more air? While there is heat, it is still 10o lower than the rest of the house.

Basements are typically colder but you could try to damper down the upstairs or look at the wiring speeds on the heater blower. They are usually marked on the motor and will give you different combinations. If you really want to go first class, install a 2 zone damper system and a separate t'stat.