Suggest reading previous postings on the subject.

Hello,
Heat pumps originally were for areas that did not have gas or propane available.

A properly designed system, will not affect the heating or cooling by using a heat pump or gas.

Gas produces a hotter air always.

Electric is a cooler process.

Heat pumps are cooler than electric.

A heat pump is cheaper to operate than resistive strips.

You need electric strips or gas for aux heat. Always.

Depending on what is cheaper, a dual heat system gives an option as to what utility is used. Either gas or Electric.

Once again, if the system is designed properly, the method of heating will be invisible.

For most home designs that have multiple stories or larger than 2000 sqft, multiple systems is the best way to design to. Very few installers know how to design multiple zones that really work, with one system.

Furthermore, In Texas, My part of H*ll, It is impossible to design a system for a larger house without using multiple airhandlers, to achieve the minimum standard, and have the system work. It is impossible using equipment made today.

Consider radiant heat in the floors, for your base heat, and the heatpump for cold days. The heatpump will also provide cooling.

IMO, SEER is unimportant. Most higher SEER systems will never save the additional cost to upgrade, before replacement time. If your PCB fails, you will never recoup the initial expense. Furthermore, using 410 systems causes more maintenance. Expensive maintenance. F22 may not be available, but there will always be a substitute freon available. Probably long after you are dead and buried.(407)

Furthermore most HVAC guys do not understand SEER. They think they do, but are incorrect. Builders know even less about SEER. Variable speed IMO is hype. It has a purpose, but as a remedial system when trying to correct high static from a fpoor design. When a variable system runs at less than full speed, the capacity of the system is reduced. If your BTU needs are 36000, then a variable speed system at 5/8 speed will never produce 36000. It may produce 20000, but never 36000. If you need 36000, then anything less will cause the system to run longer, and cost more to operate. The system will then need more repairs, because it is running too long.

Pay for a manual J. Design the system using a manual D. Design the system to have unique systems for each floor. You may share the basement with the 1st floor system, if the basement is underground, otherwise use a seperate system for the basement.

Consider solar water preheating (hot water & heating) with a boiler. Hot water heat will probably be a better quality heat and the solar will help reduce utility costs. Look at foam insulatipon and the savings of energy costs. Foam will pay for it's self within a few years. Use double or triple insulated windows. Seal all possible air leaks, use insulated recessed lighting when appropiate.

i cant see any reason for 2 systems in a 2100 sq ft ranch style house or for propane backup in georgia.overkill and a waste of money.one properly sized heat pump with electric backup is more than enough and much cheaper imho.

I also don't see the need for 2 systems in that size ranch. One would be fine with a properly designed duct system.

Propane is a very expensive fuel plus the furnace, piping & flue will be much more to put in than the electric air handler. In your climate if you leave the stat alone, you won't need a lot of backup anyway.

The first upgrade won't save you a penny. It is a 13 SEER system, not 14 as he is representing it. The XL14i requires a variable speed to get 14 SEER and the 2TEC is not variable speed. So he's quoting a nice but very expensive 13 SEER. The last system is variable speed 14 SEER but he is making a fortune on it. R410a doesn't heat or cool any better than R22.

VS blower are not hype, they are a great product. They use much less juice than standard motors, especially in the 1/2 speed continuous fan mode. They are more reliable. As duct conditions change they can maintain desired airflow. A standard motor with any restriction like dirty filter or undersized duct system, loses airflow fast. There are dehumidification capabilities, like Trane's Comfort R that suck gallons more humidity out in the summer.

How well is this house built? How much glass? We size to 95 and steamy. New construction 2100 sq ft home here would have 2.5 ton, maybe 3 ton max and be ice cold. 4 ton seems like a lot of capacity unless the house won't be well built or has a very large amount of windows. Oversized A/C can mean humidity issues in the summer.

Thanks so far. I appreciate the advise from everyone.

airsome I did read previous posts. Probably too many. That's part of why I am confused. But Thanks anyway.

Bob Brown. Thanks. I started looking at heat pumps as the area I'm in doesn't have natural gas. I probably confused the issue with the living space. Most dual systems in the area using natural gas furnaces and ac are two story homes. I thought that one system would be better because most of the time the other rooms don't have to be comfortable.
In the event of failure, which shouldn't happen in a new system anyway, we plan to have a gas log in the fireplace. My wife hates cooking on electric so we need the propane tank anyway. However, I probably would need a much larger propane tank with gas backup. This also factors into initial cost, I guess. They all have electric coil backup already, right.
From your response I should stick with the seer 13, forget the 410 and the variable speed. Put the money into insulation, right?

xracer - Thank you too. I had the same gut feel about the dual system. Gut feel isn't always right, but, unless the HVAC guy is a real engineer or really studies the subject he can mess either up equally I guess. The original dual system was to be two 2 ton units. The house is more like 2/3s - 1/3 primary/secondary living space. I was thinking you could shut one down or set it lower to save. With the unbalance, wouldn't one run more than necessary if the system isn't balanced perfect? It sounds like Bob Brown could set it right but I don't know about the guys here with these systems not being as prevelant.

The one thing the sub said was the law changes that increased the minimum seer by 3 points did more for the money than you can do by bumping it up. My gut says that placement of the ducts and thermostats problably effects performance more than anything else.
Can't you just choke down the airflow slightly in the registers when not using the secondary space. I don't mean taping them off like a NASCAR grill, just slightly. A little restriction in the one 1/3 areas will cause more flow in the 2/3s areas. That's the area themostat will be. Should reduce the run time when the 1/3 areas aren't in use.

Now I'm confusing myself.

I must have been typing when the last post from baldloonie arrived. Bald guys rule so I have to listen.
Here's where I'm at
Go with the std 13 see
One unit vs two (even the negative response was borderline, i.e. over 2000 sq ft. My house will be 5% over the rule of thumb used)
Forget all the options except the VS
Spend some of the savings on insulation and cut down on the heat loss, seal the house up tight, right.
That was easy.......
Guessing there will be a aux electric strip of some kind, if it's not included, P/N would be appreciated.
Now the size. 4 ton is too big.
Baldloonie, the builder is pretty good. There are a few extra windows. There is a view involved. They will be Alside vinyl, low e w/ argon. Fairfield 70 www.alside.com
Is too big that bad? Did you mean real dry air? Add a register for a downstairs workshop?
Thanks to all again.....
Georgia_Sulli

For a 2100 sq foot ranch, you will have zoning issues, regardless of bells and whistles. If you use one system, you will have hot zones and cold zones. If you "zone" the system with motorized dampers and extra t-stats, you will waste energy by forcing extra air through a long duct and/or by dumping too many tons of ac into a small area. Best to "zone" the house with two systems; then cheapest to regulate airflow with manual dampers. You will find that motorized dampers (with 2 systems) are more economical in the long run, but initial outlay will be higher.

It's not so much of an issue of failure as temperature. We put in a dual fuel system, but when the outside temp is below 30F or so, the gas heat is going to run. Lately that's made for an expensive gas bill on top of the electric bill. If the power's off, which seems to happen at the wisp of bad weather in GA, then neither is going to run.

Definitely second the use of Manual J and Manual D for sizing the system and ductwork. We used a guy who sizes systems and does sealing/insulation work for our calc.s. He's out toward Carrollton if you're in the general vicinity. E-mail if you'd like the contact info.

If you're interested, the Earthcraft House guidelines include a lot of info on how you can make your house more energy/resource efficient. It's a program by Southface Energy Institute and the Atlanta Homebuilder's Assn. I'll link the guidelines in below.

Here is a link that might be useful: Earthcraft house guide

When you choke down the airflow when "not in use," you change the sizing requirements of the system. If you think certain registers will be closed off on a regular basis, you will need a smaller system to condition the rest of the house. If you would rather control such a space thermostatically, you will need a motorized damper. You might prefer one designed to close to a specified opening. Some damper manufacturers insist on closing all the way. The damper must be controlled by a separate thermostat.
When you use a single system and zone it for the whole house, engineering becomes critical. You do not want to send 4 tons of AC into a 1-ton space.
If you use 2 systems, say a 2-1/2 ton and a 1-1/2 ton, then zone one of the systems with motorized dampers, you send much less AC to the 1-ton space. Your system is more efficient; it produces less stress on the furnace and ductwork; it reduces humidity in summer more effectively, thus allowing a higher tstat setting. At the same time, the other system runs less often.
Variable speed furnaces had problems in the 1990's, but the kinks have since been worked out. Nowadays, VS is the only way to go. It is so quiet you can't hear it. It uses as much energy as a 100-watt light bulb. Costs of replacement parts have dropped dramatically. Dehumidification is increased, so comfort level is less dependent on temperature (similar to above with smaller system). The furnace pays for itself, then it pays you back in larger amounts than a less efficient one.
What does efficiency mean? Say your old system operated at a SEER of 7. If you replace it with a 14-SEER, your operating cost is cut in half. (This is in a laboratory setting, just like EPA milage ratings on cars.)
Regarding R-410 vs R-22: I recently bought a large quantity of R-22 for a fairly low price. In a month or two, I doubt that anyone will be able to find it for less than 30% more than what I paid. Many suppliers are charging more than that now! R-410 prices are dropping slowly, but will soon drop faster as the market dictates. Two years from now, NOBODY will buy an R-22 system.
What does this mean for the homeowner? When you have to repair your system, you will probably have to replace some refrigerant, and you will be glad you had the foresight to buy the R-410.

Hello,
There is a drop in replacement for f22. It is f407. It will probably take many years to cost more than f410. With the number of f22 systems installed, as the usage decreases and f410 increases, there may be a point where f410 is cheaper than f407. Maybe in 2030 or so.

I have not seen 407 used here in Georgia. Nor have I read about it in the HVACR newspapers. Nor do I know any suppliers in the Atlanta metro area who stock it.