I bought a 3000 sq ft ranch (built in 1958) on a slab in Northern Kentucky (greater Cincinnati) about a year ago. Have lived through one cooling season and are coming to the end of our first heating season.
Existing HVAC system is as follows:
Heating: Gas-fired hot water boiler using baseboard fin radiators. Radiators are zoned into 3 zones which do not work particularly well. Too much heat in some rooms of zones, too little heat in others.
A/C system: Standard split system with air handler and all ductwork in attic. Round ceiling diffusers for supply. Both units (indoor and outdoor) are very old and need to be replaced. To my untrained eye, the ductwork needs to be totally replaced. It is done very poorly. ALL supply ductwork is flex (including main trunk). Poorly supported, many bends. It is not sealed very well. I afraid to think how much of the attic I'm cooling. There is very uneven air flow from the registers (too much from some, not enough from others, etc.). Two return registers - one with a filter grill in the hallway (right below the unit) and another about 40 ft. away (in the family room ceiling).
If the radiant heat worked better and was in better shape I would stay with this for heating and just replace the A/C. Since it's not this is what I was thinking about doing:
Installing a new variable-speed gas furnace along with a heat pump to handle both heating and cooling. May also want to zone house using dampers, etc. I have had several contractors give me estimates for replacing the A/C unit (only) and haven't been impressed. None has done any load calcualations. Their main question has been to ask what size unit I currently have and how many square feet the house is.
My questions are as follows:
1. How well will forced air HEATING work when using ceiling diffusers? I know cooling is not an issue.
2. Are there certain types of diffusers (or ceiling registers) that would be better - that can adapt air flow patterns for either heating or cooling?
3. Is it still acceptable to have returns in the ceiling? I got one estimate for A/C only, back before I thought about this idea, where the contractor was going to add additional returns in the ceiling. Is this okay?
4. Is a heat pump (+ gas furnance as backup heat) a viable (and smart) option? It definitely gets too cold for a heat pump only.
I know this is a long post. I would appreciate anyone's comments to the questions I have.