If you have the existing ductwork in place for the central air, it may not be much of a job to switch over to forced air.

Is the central air via traditional duct work or mini ducts?

A new furnace may seem like a large investment but the saving will come back quick with less fuel use, electric water heater dont have the recovery rate as gas and a power vent will run you ( here in ND) approx, 2-3k installed 1,500 to 2000 homeowner installed, a furnace installed (reusing exsisting A/C and duct work) around 3-4k (also in ND).

The price is completely dependent on what's left of the previous HVAC system.Is duct work, etc still in place?

Thankfully it didn't have forced air, so the ductwork didn't need cleaning.

The local gas utility should be able to identify how close the nearest gas line is, and how much it would cost to connect to it.How expensive it will be to run ductwork depends on the number of stories/floors/levels in the house, and how easy it would be to get the ductwork into place.

No ductwork, or plumbing yet exists. the electrical box is in and the main outlets are in place, fixture and additional outlets still need to be installed.

Furnace Air and ductwork 10,000.

Most rehabbers that i know don't pull permits for anything other then serious structural work that changes square footage (room additions, expansions) and other new beneficial additions that need to be reflected on the title or public records (new HVAC with ductwork, changes of gas water heater to electric, etc).Hire a good good licensed contractor to give you an unofficial honest opinion for a nominal fee, make notes of everything he says, then hire an official inspector, see what he finds and also point out the things contractor mentioned to discus further.

Assuming the house had nothing but a gas wall heater (required by code), and you're putting in a complete HVAC system, with ductwork, compressor, furnace, permits etc. - so central heat and air.For reference, i have a 3 bed 2 bath bungalow in North East Los Angeles that i'm about to finish remodeling, and am now contemplating new central air in.