Gas and Oil Home Heating Furnaces - Split-level heating/cooling problems

I have a 1 year old split level house built on a concrete slab. There is only 1 HVAC unit. The thermonstat is in the upstairs master bedroom. The house is approx 2100 sq. ft. Even after closing most of the upstairs registers and double checking that all downstairs registers are fully opened, I cannot heat the downstairs without overheating the upstairs. The opposite happens in the summer. The HVAC is quite large, however I cannot remember the exact size. The A/C seems to work better than the heat. All rooms have both a supply register and a return vent.

Any ideas on how I might be able to balance the heating system better?

I am beginning a fight with the builder to install a second unit.

Thanks in advance.

you will need to install a large return air grille to pull the cold air from the basement. This will help. my furnace is pulling strickly from the basement and it has warmed the bottom floor by 5-10 degrees. although i will redo the return air duct when i'm finished installing the 90% furnace, i am certainly going to add some return air grilles in the basement. note: i have a two story house, and the upstairs are a little colder during this.

Unless your house was zoned, you'll probably not be able to accomplish the uniform heating and cooling you wish. Remember, slabs are cold all year round. I would get the slab heated and solve the heat problem. Two systems for that sized home would be much more comfortable, but still the slab would be cold in the winter months.

If your having problems with heating the basement even after closing off your upstairs registers, then the vent system must not be that well designed in the first place. Quite common that basments aren't given a lot of consideration sometimes when it comes to ventilation. Return air in the basement (lack of) often is a large part of the problem. Also if you have cooling in the home and the hvac company that installed the system sized the vent for cooling and not heating, the basement might recieve much less air than the upper part of the home. This will result in less heated air in the winter resulting in a cold basement. If you can have the hvac company out to re-balance the system to help eleviate the problem. Thermostat in the bedroom.....hmmm interesting. Good luck