Hopefully I have posted this on the right thread - if not I apologize. My wife and I are trying to decide on whether we would be best to upgrade our HVAC system or add insulation to our house. I know that this shouldn't really be an either or, but both cost $$ and we can only do one. To help with any suggestions, here are some additional details:

Our house is a 1948 brick ranch house in central Alabama. The walls have no insulation and the attic has some older insulation (estimated R-value of about 10). The roof is a light colored metal. Our HVAC system includes aging ductwork and a massive air handler/furnace unit that is probably 30+ years old. The AC unit is around 6-8 years old. In the summer our AC unit will run for about 12 hours a day (continuously). In winter the furnace never runs for more than about 30 minutes.

We have received quotes for a new heat pump/air handler package with new duct work and would love to go with that option, but at this time it would be a strain on our limited resources. The other option that we are considering is adding insulation to the attic and possibly adding sprayfoam insulation to the exterior walls. Based on the estimates we have so far, the insulation would cost about about 1/8th of the cost of the HVAC system.

The question that we are trying to answer is: which would be the better use of our limited funds - a new HVAC (heatpump) system (including ducting) or adding additional insulation?