Sounds like you have too much airflow going upstairs and not enough going downstairs. Try shutting down the dampers in the upstairs ducts until it evens out the temperatures.

Albeit incorrect what you have is not at all uncommon. Air distribution is a specialized field of hvac that most contractors are under qulified in and fail to sub-contract out during installs. With that being true,you will only make it worse trying diy with instructions furnished by people on the net. I suggest contacting a contractor specializing in ventilation and air distribution.

Go into the attic and inspect the duct work carefully. Most likely it is flexible that could either have a bad kink or leak. This could be a reason why the first floor a sufficient amount of air. See if there are any damper controls for the duct work going supplying each floor. If you are lucky, you might be able to reduce the flow to the second floor and increase it to the first.

If you are not able to make any improvement in the attic, then you could close one or more registers on the second floor. Experiment by closing a register that has the strongest air flow, or one that is closest to the attic. Wait a day or two to see if it has made any change in the temperature difference. Don't close too many dampers. That could cause additional problems.

If that has no success then bring in an HVAC contractor to examine what you have. You may be able to create separate the system into two zones. But it most likely mean you will have to purchase a 2-stage variable speed air handler and install a second thermostat on the first floor.

Common problem. Probably need new supplemental runs to both upper and lower floors with manual dampers. Close upper runs/ open lower runs during winter and close lower runs/open upper runs during summer. (Heat rises, cold sinks). Similar idea for basements, closing lower runs in summer keeps basements from getting uncomfortably cold, opening lower runs in winter helps keep basement warm in winter. This is the most uncomplicated way to solve the problem, and how I did it in my house (main floor and basement). Also adjustable on the fly if needed.

"In the summer its the opposite....when I run the A/C the upstairs feels like 75 while the downstairs feels like 85"

AT first, I thought of switching the dampers in the spring and fall but given the OP's statement above, it sounds like there just isn't enough air (hot or cold) going downstairs.

With a two story house, zoned HVAC units are the only way to go. Otherwise, one is hot on one floor and freezing on the other.

I agree you need enough airflow for your unit to work, that's why I said new supplemental runs which can be dampered without hindering the existing ductwork. Supplemental as in extra runs. Easier said than done though in a finished house. Worth breaking up a wall section and running? Possibly. Depends how bad your comfort is. I did have to do extensive tweaking to my ductwork to get the house in a good state. Probably will have to for the next house I move in too.

I just like to keep it simple, running different zones and trying to get the motorized dampers working is all extra complications. Also, your furnace may not do multi zone anyhow.

No one wants manual anything these days. People want control from a smart phone so they don't even get up from the couch. If I were to try to sell a manual change over system no one would want it.

Just before Christmas the lows were in the 30's where I live. On Christmas day we were in the 80's. How many times during a winter are you going to want to change settings on a manual damper?

How great it is to be able to walk over to the thermostat in my house and set the temperature without having to go into the attic to adjust a manual damper. Say hello to 2016. Say good bye to the 1990's.

Vith,

There's nothing wrong with what you've done necessarily. But because the manual adjustment requirement it would be something I would never offer any more because I would be constantly called to make and adjust the manual adjustment.

Everyone would love to have remotely controlled versus manual dampers. But there is a significant difference in price. People have to decide for themselves how to spend their money on the additional convenience.

The original intent of this thread was to help the original poster do his own investigation before having an HVAC contractor come in and sell him something. The OP can decide how much money he wants to spend on the trying to balance the two floors.