I would look at the SEER rating of the existing systems you have, and investigate at least changing out the furnace coil if you can get 2-4 SEER more than what you currently have. You won't believe what a difference a system that is the proper size for your dwelling and that is a higher SEER rating can do for your utility bills. Add a programmable thermostat and your savings will be even higher.

Here is a link that might be useful: Programmable Thermostat

Just a couple comments:

First, that's a pretty good price on the Comfort 16. That's $200 less than a quote I received two weeks ago for a 2-ton version of the same model.

Have you analyzed your past few years' worth of utility bills to estimate how much benefit you'd gain from a new system? I went through this analysis recently and found that, given my average a/c usage over the last 8 years, the 16-SEER unit would save me around $40/year over a 13-SEER unit at current electric rates. I'd have to keep it for 25 years in order to justify picking the 16-SEER unit over the 13-SEER unit. Your results will differ, of course, but the analysis might keep you from spending more money than you need to on your upgrade.

Thanks for the responses. I will definitely be replacing the furnace coil and going with at least the Comfort 16 because of the pricing. The 13 SEER was only a couple hundred less.

I am still considering whether to take advantage of the tax credit which would allow me to get a new furnace to replace my 11 year old one (runs fine) for about $1000.

arcas,
Your comments make sense if there is no Fed Tax credit, but $1500 back with a qualifying system vs nothing back with a 13 SEER system makes your math incorrect at least until the tax credit is no longer applicable. Not to mention you assume that electric rates are constant. Not sure about your area but here in MD my rates doubled in the last 3 years. I don't see them going down so that $40/year here would be $80 in short order where I live. Based on your calcs that would equate to ~14 years.

craigva,
The question you need to ask yourself is what are you looking for in a system. If you are looking for better dehumidification or more stages of heat to provide a more comfortable living area than by all means pay to make it so.

Also, the most important part to take into account is the installer. Any system properly installed will serve you well. It's not just about cost. You can go cheap on the install and just end up paying on the back end in repairs or early replacement.

I'm just a homeowner in the DC (MD side) area and just went through all this. I went with a hybrid (HP/Furnace) system.

emarston: I did say that the results will differ. However, I'm quite comfortable with my estimates and projections for my particular location.

My situation:
Dual 10-SEER a/c units and dual 80% gas furnaces
Current effective electric rate: 0.08/KWh
Current effective gas rate: 8.50/Mcf
Average a/c power over last 8 years: 2957 KWh/year
Average gas used for heating over last 8 years: 50.52 Mcf

And for prices, I'll use my lowest Carrier quotes...
13-SEER 24ABB324: $3187
16-SEER 24ACC624: $4118
95% AFUE 58HDX60: $2987

Now, let's put everything together and assume that keeping the current a/c units is not an option for whatever reason (failure is imminent, etc):

**Option 1** Replace my existing a/c units with 13-SEER units. Keep my existing furnaces. Let's call this the baseline. Overall cost is $6374.

**Option 2** Replace my existing a/c units with 16-SEER units. Keep my existing furnaces. This carries a premium of $1862 over option 1. Given my average annual usage, this setup saves $34/year @ 0.08/KWh and recovering the premium will require 54.7 years. If electric rates suddenly jumped to 0.20/KWh, this setup would save $85/year and recovering the premium drops to 22 years.

(In fact, rates would have to jump to $0.33/KWh before I could reasonably expect to recover the premium within the lifespan of the a/c units themselves)

**Option 3** Install one 16-SEER a/c, one 95% furnace and one 13-SEER a/c unit leaving my other furnace alone. This lets me qualify for the tax credit (I think). Overall cost is $4118+2987+3187 - 1500 = $8792. So, accounting for the tax credit, this option commands a $2418 premium over option #1.

This option results in an overall ratings of 14.5-SEER and 87.5% AFUE.

At the current rates of 0.08/KWh and $8.50/Mcf, this option will save $19/year for cooling and $37/year for heating for a total savings of $56/year. I'd recover this premium in 43 years.

At 0.20/KWh and $26/McF, this option will save $47/year for cooling and $112/year for heating for a total savings of $159/year. Premium is recovered in 15 years.

**Option 4** Install two 16-SEER a/c units and two 95% furnaces. Overall cost will be (2*4118) + (2*2987) - 1500 = $12710.

At the current rates of 0.08/KWh and $8.50/Mcf, this option will save $34/year for cooling and $68/year for heating for a total savings of $102/year. I'd recover the premium in 125 years.

At 0.20/KWh and $26/McF, this option will save $85/year for cooling and $207/year for heating for a total savings of $292/year. Premium is recovered in 43.5 years.

Moral of this story: just because Uncle Sam is waving $1500 under your nose to buy a system with certain minimum specifications doesn't mean that it's a good deal.

Arcas,
I can appreciate your calculations (I spent a month doing the same thing while also getting multiple estimates from 10 contractors), but after researching I discovered is more than just rate of return from system efficiency. As previously stated there are differences in build quality, controls, noise, and most important installation quality.

For your analysis I will assume you include any local utility and state rebates (That reduced a qualifying furnace and HP by $400 a piece where I live or $350 for an A/C). In the OP's case it is the following for VA:
Gas Furnace (ENERGY STAR qualified): $250
Heat Pump (ENERGY STAR qualified): $300
There are also manufacturers rebates to account for(although I think that season may be over at the end of June). I will also assume you could care less about noise as you get a good bit more of it in a basic system (I know as it's night and day from my old system to my new one) or the excellence of an Infinity controller in the OP's case (it can control dehumidification in the summer, a humidifier (if desired), tell you when you need to replace your filter, and let you know if something is wrong with the system). A nicety, yes, but some people like to have a better quality and more capable item. Kind of like buying a car.

Regardless, Option 2 should include the tax credit as it should be a qualifying A/C system (since you should be able to replace the inside coil for compatibility purposes and 16 SEER should qualify. This is assuming you don't have ancient furnaces). This would drop the difference to only $382 which you would gain back in the expected life of the system.

Option 3 doesn't take into account you have a brand new furnace which will not have to be replaced for at least 10-20 years. Unless you have relatively new systems. Either way you shouldn't have to replace them if you drop in a straight A/C since that can be tax qualifying on it's own. (see option 2) You should not assume equal usage either due to varying heating and cooling loads, but I get that it is for simplicity.

Option 4: Well, not going to argue costs there as you are getting 4 new systems.

The $1500 can be made useful especially if you have good local rebates for high efficiency systems. I have no idea how old your furnaces are, but if they are more than 15 years then it's likely they won't be long for this world. In the OPs case if they keep the furnace and sell in 5-10 years expect to give credit for a new one (I know I asked for credits for systems I knew needed replacement when I bought).

As with many things in life there are many factors to take into account(more than I was willing to spend time on), so in the end I suppose the answer must be it just depends...

Excellent debate and helpful. Key points to me are quality of the equipment and the new furnace vs. keeping the old one. From my perspective the new furnace will cost me about $1000 ($2500 minus the $1500 tax credit). Seems like a worthwhile investment.

After making that decision the next one is to spend another thousand to move to the 2 level systems and possibly the hybrid system. While the completely objective monetary analysis may show many years before I break even, I still have the sophisticated system that keeps my humidity and temperature very stable.

I have used several sources (mostly Washington Checkbook) to find three highly recommended for quality companies to get my quotes from as I understand without getting the right equipment for my house and having it installed correctly, I would be wasting my money. Actually I started with five but two have eliminated themselves. The last three all sell Carrier. I have one more bid coming soon after a visit tomorrow. I need to make my decision quickly if I am going with the Infinity system as the 1000 rebate expires next week.

emarston, are you willing to tell me what equipment you ended up with?

Thanks

I ended up with an Infinity Hybrid Heat setup of 25HNA9 HP and 58MVC furnace. We also plan on being here indefinitely so that was a factor in our decision process. Good luck.

I have made my decision. I decided that it was worth the money to first, add the new furnace and second, go with the Infinity system for the additional comfort that the system will provide. I also added the whole house humidifier as my house is dry in the winter. I already have an air cleaner which if it stops working in the future can be easily replaced by a media filter. I went with a highly rated (Washington Checkbook) company who was the only one of 5 to do a Manual J.

I appreciate the assistance and opinions including those in the other threads that I have read in this and other forums.

The system that I am purchasing:

AHRI 3638148
Performance 24apa748 4 ton 2 stage air conditioner
Infinity 80 58cva 110-20 2 stage furnace
CNPVP6124ATA coil
Infinity Controller SYSTXCCUID01
Carrier flow through fan powered humidifier LFP1418
5 year labor/10 year parts warranty
Reuse lineset after nitrogen flush and vacuum (mine would be difficult to replace)
Net Cost after Carrier rebate and tax credit $6550