Basement heating

[dmkraft]

Hi, I have a 6 year old 2,400 sq ft ranch with a basement with 1,400 sq ft finished. I have ceiling heating and cooling ducts in the basement area. The finished portion is divided into 4 rooms. I heat and cool a total of 3,800 sq ft. I do not have zone heating. I live in Wisconsin. The only thermostat is on the main floor. the stairway to the basement is open. In the winter the basement is at least 5 degrees cooler than the main floor. If we have the thermostat set at 68 it is only 63 or cooler in the basement. We have used electric baseboard heaters but they are very expensive to run. I already partially close the main floor registers and open the basement ones completely. In the summer the opposite occurs, the basement is much cooler than the main floor when the ac is on. I of course close the basement registers in summer and open up the main floor. I can't do much with the duct work as the ceiling is finished in drywall. Is there anything I can do with the current forced air gas system to make the heating more balanced? Do I need to add a second furnance and ac unit to set up zone heating? Is there a supplemental heating source that is cheaper to run than electic baseboard heaters? I am more concerned with the heat in the winter than the cooling in the summer. Thanks for your help.

[Hube]

First of all do you have sufficient RETURN air in this basement area? Depending on the layout of these various rooms in this basement you may require 2 or 3 RETURNS. (Normally one is sufficient in a open basement)
Also,do the basement exterior walls have any INSULATION? (r value ?)
if the answer is 'no' to the above questions, then that is the main reason for your problem.
if the answer is 'yes', then you could try running your furnace on a continuous "LOW" speed in the HEATING season. This continuous LOW speed will allow the air to circulate into both areas and in a short time the temperature in the 2 levels will somewhat be close to being equal.

Another idea would to re-locate the T-stat into the basement area. Of course you would have to slightly 'damper' down the supply registers in the upper area somewhat.

If you post back with some answers to the above questions, I, or others may try to help you further.

[dmkraft]

I only have one cold air return in the main room, none in the three smaller rooms including the bathroom. Also, the basement exterior walls are fully insulated. I have a partial exposure. I don't know the r factor but the insulation is quite thick. The walls are 2x6 construction over insulated block.

Do duct booster fans work well? I have access to the individual room ducts where they join the main trunk.
Thank you for your quick reply to my problem.

[Hube]

Since you say you have a return in this basement area it should help if it is large enough in size.(see note below) In order to draw return air from these other basement rooms it would mean the doors to these rooms would have to be ajar, or if closed they would have to have at least an inch or so of "undercut" at the floor level.
Rather than resort to booster fans it would be best to have the system "air balanced" by an hvac pro using the proper air measuring instruments. This will allow more supply air into these "starved" areas while lowering the amount of air flow to other areas. Since you say you have access to the duct connections, etc, installation of dampers would be easy.

Note; Return air is very essential to allowing adequate supply air into a room. Without adequate return air the supply air is greatly hindered. Usually, the amount of supply air that can come INTO a room is controlled by the amount of return air that is being taken OUT of it.
Again, return air in this finshed basement area is quite essential. Just make sure there is enough.In your case 30-35 % of the total return for the entire home should be taken from this finished basement area.

[Runs with bison]

As Hube says, the return is very important. I have one sub-basement level with zero returns. Why they constructed it like that is beyond me. It is open to the adjacent half level, but it operates as a sink that the cold air from the whole house falls into. Warm air enters through a single ceiling register. Without a return the register air short cuts from the register across the ceiling and into the hall above without doing much in the room. If/when I tear into the main duct runs for the home to fix balance issues, one thing I intend to do is put a large return near the floor of this room. Doing so should allow some actual circulation through the room and reduce the thermal gradient in the home.

[PistonDog]

DMKraft,

I'm in the same situation, so I'll suggest the same path I'm investigating (see my post about fresh air intake). If your furnace has a vent (pipe) from the outside to supply combustion air, nevermind you'll have to find another solution.

My problem is the furnace gets its combustion air from the basement, which means that that air is replaced directly into the basement from the outside cold air, hence making the basement colder.

To think of it another way, the air & exhaust gases that go up the chimney have to get replaced somehow. Unless there is a 'fresh air vent' to supply air for the combustion chamber, it comes in from the outside of the house through the minute cracks around (in my case basement windows) the exterior walls.

There may be some drawbacks to this approach (higher moisture in living space*), but I think some states (mn) have mandated it it for new construction, and some new furnaces require/desire it to achieve their high efficiencies.

good luck.

PD
*The higher moisture may result from less dry air entering from the outside into the living space. This may or may not be a bad thing, but ultimately could be controlled.