Geothermal systems do not cost more to install initially from the point duct system requirements. ALL HVAC systems [forced air] need to be designed to carry the amount of air required to operate efficiently and at maximum capacity. Generally, this is 400 CFM per ton of refrigeration capacity. A 3 ton air source system requires the same amount of air flow as a 3 ton geothermal system. Therefore, there is no difference in the initial install costs between the two.
Where the duct system cost vaires is the system design. A box and flex duct system is cheaper to install since the sheet metal used is reduced. Sheet metal duct systems require more time to fabricate and install, therefore it simply costs more. A box and flex system, sized and installed correctly will perform correctly and efficiently. But it is not as durable as a sheet metal system. Basically, it is a trade off. Sheet metal is more durable and will typically last forever, flexible duct typically does not. Sheet metal is easier to clean whereas flexible duct is easily damaged during cleaning. This is a basic senario and complex designs definitely affect install costs.
Where the geothermal system install costs come into play is the equipment costs and loop installation. Geothermal systems simply cost more to manufacturer. The loop systems require more labor to install versus running copper lines to connect standard air source systems. Loop systems, either high density poly [HDP] for water source systems or copper loops for DX systems require excavation or drilling. This is another initial install cost. Typically, HDP requires more linear footage than copper loops since copper is 400% more conductive than plastic. So in theroy, less excavation or drilling is required to install DX systems. This however comes at a price...copper is expensive. So there is a balance there between the initall install costs of each system. Only the bidding contractors can determine what this will be.
Since more labor is required to install geothermal systems, this also affects the initial install cost. Labor rates vary nation wide, so don't expect labor to install a system in Georgia to be the same in California. This is simply a regional cost that varies from state to state. Drilling and excavation costs follow the same path.
A HVAC companies operating costs will vary also. Fuel costs vary from state to state. Insurance [vehicle, liability, health, workmans compensation] all vary from state to state. All these items affect the bottom like...consumer cost.
The HVAC industry has undergone drastic changes in recent years. Nearly every component used to install a HVAC system has experienced price increases. Code changes now require higher efficiency systems, greater insulation values on the duct systems and a host of other items that affect the bottom line. Refrigerant prices continue to rise. So does fuel costs, labor rates, operating costs, etc.
In sumary, don't expect to get the same install costs from one state or region to the next...it won't happen.
Now, is a geothermal system worth the additional cost? What is comfort and efficiency worth to you? I have never gotten an answer to that question. There are a number of things to consider.
Typically, a geothermal system will have a payback period of 5-7 years between the cost of installing a high efficiency air source system versus a geothermal system. If you are going to install a geothermal system and move from the home within that time frame, you probably will not experience any energy savings. Now consider that the national life expectancy of an air source system is 10-14 years before the system will have to be replaced. This is an important fact to consider. Geothermal systems typically have more than a 30-year life expectancy.
Lets say that a geothermal system costs $20K to install versus $10K for an air source system. Given current prices and inflation, replacement cost of the system could easily reach 75% if the initial installation costs. Therefore, the air source system would require an investment of $17,500 during the first 10-14 years of the systems life. Given this, you would have to save $2,500 in energy costs alone during the first 14-years of the systems life to equal the initial investment cost. Is this possible...its more than probable! That amounts to less than $15 per month! It is well known that geothermal systems are the most efficient operating systems on the market today.
Now consider the effects of installing a geothermal system. These facts can be found on the geoexchange website.
1. There are around 1,000,000 geoexchange systems installed in the US to date saving more than 21,000,000 barrels of crude oil each year!
2. Installing a geothermal system has the same effect on the environment in greenhouse gas emission reductions to equal planting an acre of trees!
3. Replacing an existing fossil fuel burning appliance further reduces Co2 emissions and reduces our dependancy on foreign crude increasing our national security.
4. Reduces the energy requirements on our power grids, which are already greatly over loaded as evident by rolling black outs.
These are just a few of the many benefits of geothermal systems. Now, do these systems make since?