Do you have to run duct work?

However, if you are already doing extensive work, you may want to to already plan for it such as doing the ductwork or figuring out how ductless could provide a solution.

I am looking to replace the existing HVAC system in the attic of an 800 sq. ft. single family home that’ll require replacement of existing furnace and new ductwork.

Systems will run $7k each assuming ductwork is already in and in serviceable condition.Doors: $5,000 - Probably ok with this budget may may go over depending on total quantity of interior.Interior trims: $2000Counters: $4,000 - Should be ok with this, perhaps slightly low depending on type.Contingency: $15,000 - Great.Total: $150,000 (need to edit your total now based on above and below:Electrical: ??

Beware of old knob & tub wiring along w/ galvanized piping/ductwork.

The hvac was redone in 2018, but only some of ductwork was redone.

From what I have heard is that they are far too noisy to be practical.I am also totally willnig to change the ductwork if required.

Just replacing a 3 ton HVAC gas heat no duct work,  No more then $4500. 

You might run into adequate HVAC capacity and needing to run additional ductwork (then determining a pro-rata billing set up perhaps) or even an additional unit with separate water meter just the same. 

Then, you need to call in the appropriate vendor, repair person, or replace the appliance.For example, the policies/brochures that I have seen say (from memroy here) that for a forced hot air furnace they don't cover the burners, the fan / fan motor, the induction motor, the controller electronics, the ductwork, and the heat exchanger.