An 80% efficient furnace simply tells you how much fuel is used to heat the home and how much goes out the flue. A two stage furnace will be more efficient than a single stage for the simple reason it burns less gas when in 1st stage. It all depends on the CLIMATE in which you live.

It makes no sense what so ever to go above 80% efficient in a warmer climate. In Katy, Texas where I live... we have virtually had no winter for the past two years. Unless you count the 2 weeks or so we dipped into the 30's.

A 2 stage, variable speed furnace is required to make an air conditioner efficient and operate as designed. The 80% number only relates to when you run the furnace for heat.

2 Stage AC while is efficient, this equation is more about comfort. Just a plain 2 stage AC is very dumb this day and age. If you are going to go this route the better of these is what is called a communicating system.

The thermostat along with the equipment chosen is what makes this work. Sorry nest this doesn't include you.

A Communicating system means: the thermostat communicates with the indoor and outdoor equipment to give you the best comfort you can imagine. [When installed properly. Skilled labor is required - choose carefully]

If you live in a dry climate a 2 stage AC may be over kill.

Another advantage of a communicating system is algorithmic operation of the system. It knows outside temp, inside temp as well as humidity.

Because temps are constantly changing inside and out gives this type of system an advantage over others in extreme climates to one degree or another.

Thanks for the replies!, I am in Plano, a northern suburb of Dallas, TX.

My home is 3500sf, with about 1800-1900 downstairs. This is the unit I am planning on replacing. I had replaced the upstairs one 4 years ago with another R22 system (just condenser, and coils, not furnace).

I have Atmos Energy as gas provider and Coserv Electric as my electric provider.

Not sure why none of the 3 installers bothered with a sizing, they just went by what I currently have (4 ton for downstairs and 3.5 for upstairs).

Here is the exact details of the 2 stage system I am being proposed for $7900:

http://www.greenleafair.com/#xl_xr_page_4ton-infinity-carrier

I think this is the Infinity controller and would provide the communicating features?

And the single stage for $6300:

http://www.greenleafair.com/#xl_xr_page_4ton-carrier

One thing I found out is that Atmos Energy gives a $350 rebate for 90% - 94% AFUE furnace and $500 rebate for 95% or higher AFUE.

I also found out that I will be charged $2000 extra to upgrade the above $7900 system's furnace to Carrier Infinity 96.7% AFUE furnace Model: 59TN6

After the rebate, that's an extra $1500 for the upgraded furnace for a total cost of $7900+$1500=$9400 for one 4 ton 2 stage Carrier Infinity.

That's a lot of $....Given Dallas area humidity levels around 80% in the AM and 50-60% in the PM throughout the year, is 2 stage worth it?

Also, for winter, Plano does get snow 2-3 times in the winter and gets in the 30's at least for a total of 3 weeks or so, would the upgrade to 90+% AFUE furnace be worth it?

If I lived in Plain Ol' Texas, I would seriously consider a 2-stage, variable-speed blower air conditioner system. I will also say (and several here will disagree) that you can get good (perhaps not great) humidity control with a single stage AC with the variable speed blower. That would save you a few bucks, but you would need to look at the difference in price to see if it is worth it to you. Note that due to your longer shoulder seasons, you would use the low stage AC more than others living farther north.

As to the furnace, since you have a short heating season, you're only talking about a 10% savings in your gas bill during those months that you use the heat. Chances are you would never make back the money in gas savings that it costs for the higher efficiency unit. $2000 I bet buys a lot of gas.

I agree with weedmeister,

while your location does get cold that cold is really not cold enough to justify anything over an 80% gas furnace. They make 80% furnaces with variable speed blower and these variable speed furnaces tend to be 2 stage furnaces. The variable part of it is the blower, so you understand what I am saying.

Certainly you can pair a variable speed furnace with a single speed air conditioner and gain some dehumidification attributes... just no where near that of a two speed. Once you get to shoulder seasons the single speed will not dehumidify worth a lick, because it will over cool so fast and shut off. (It doesn't do anything if it's off.)

A two speed AC with variable blower will run in first stage AC mode and has better capability to dehumidify because it runs longer at reduced power. This is the best cost option for dehumidification.

Now if you go to a communicating system like infinity or other manufacturer offers... you get the best of both worlds. You'll pay more for it, but comfort wise you will reap those rewards everyday. Just make sure you go with a contractor that is in it for providing you with service should problems arise.

Not sure why none of the 3 installers bothered with a sizing, they just went by what I currently have (4 ton for downstairs and 3.5 for upstairs).

I know it gets hot in Plano (summer design temperature is at least 98 degrees) but I think 7.5 tons is over sized for a 3500 sq. foot house. In a very humid climate it is better to be a little undersized than oversized.

The 95% efficiency furnace will cost $1500 after the rebate. You will never see a return on investment in your climate. However the choices in 2-stage furnaces at 80% efficiency are limited. Very few have variable speed. The Carrier 58CVA furnace is a 2-stage with variable speed. That furnace with the Carrier 2-stage 24ANB7 condenser with the Infinity controller would do very well in a very humid climate. This assumes a properly sized and installed system.

You two floors are about the same size. So I am curious why you have a 4 ton condenser for downstairs and a 3.5 condenser for upstairs. That seems backwards to me unless you have a lot of south facing glass on the first floor.

I am also curious about the R22 condenser and coil you installed 4 years ago. Did someone advise you to buy an R22 system? If they did then that was bad advice in my opinion.

I think 7.5 tons is over sized for a 3500 square foot home.

I doubt it. Building standards of today likely do not equal those of when this house was built.

Dallas area can be under dry heat for extended periods just as much as high humidity. Different locations call for different measures.

However the choices in 2-stage furnaces at 80% efficiency are limited. Very few have variable speed.

You are in the north Mike... are you not? I don't think EPA efficiency standards allow 80% efficient furnaces in your area.

I have no problem finding these furnaces in Katy, Texas. But I can't find a 13 SEER AC unit.

You know why???

How were you able to figure out when the OP's house was built? Whether it was built 30 years ago or last week it doesn't matter if a load calculation is done. I know you think load calculations are a waste of time and money. I just cringe when I hear someone sizing an AC condenser based on 1 ton per 500 sq. foot in a very humid climate.

As far as I know you can still buy and install an 80% efficiency furnace in any part of the country. I think there a few choices in terms of features with the 80% efficiency models but this may vary among manufacturers.

I do believe the limit for AC condensers in the south is 14 SEER, while it is still 13 SEER in the north. Not sure what that really means since the SEER rating for a combination of condenser, coil, and air handler or furnace for a matched system.

The reason you can't buy a "13 SEER" condenser in Katy, Texas is because your local distributor does not want to stock them. The U.S. Department of Energy (not the EPA) may enforce penalties on sales in the south. I would be curious how a distributor in Delaware, who is right at the north and south border, handles this situation.

wow, good information. Ya, i guess if running my heat for 3-4 months out of the year, the extra $1500 for higher efficiency furnace isn't worth it.

I am still not sold on the 2 stage argument. It's not as humid here as Houston. On the contrary, in winter, when the heat is on, we feel it is too dry inside the house and my son has gotten nose bleeds as well, we now have a humidifier in his room.

I would think going to 2 stage would make it even drier no?

Again, some quotes are upto $3000 more for upgrading to 2 stage. The cheapest one above is $1600 more for 2 stage ($6300-single or $7900 for 2 stage).

Somehow I am apprehensive about an ac running all the time (at least for a lot longer) albeit at lower capacity/electricity/speed vs a single stage that runs for a shorter time and shuts off. Yes, there will be more of temperature swings due to the single stage having to cycle on/off, but other than the more steady temperatures, the other positive (dehumidification) seems to be a negative for us. Am I incorrect in my assumptions of what a 2 stage buys me?

Thanks

KG

"You are in the north Mike... are you not? I don't think EPA efficiency standards allow 80% efficient furnaces in your area."

EPA has absolutely nothing to do with it. DOE is the operative organization.

There is no restriction on 80% furnaces in "your area." You may want to check with someone in the trade on what furnaces are allowed.

We lived in San Antonio for 30 years with a 2-stage Carrier (1992 vintage) and never got good humidity control until we added 600 square feet to the house and installed double pane windows. We did not change the AC unit at all. Clearly something was wrong with the original calculations, but we could never figure it out between shade and single pane windows and leakage. Later we switched out to an Infinity furnace and thermostat. After that it became extremely comfortable with excellent humidity control. The variable speed fan and Infinity controller made a lot of difference.

If you live within 200 miles of the Gulf Coast then I would insist on something equiv to the Carrier Infinity. Beyond that it would depend on local humidity conditions.

Apart from the decision to do 2 stage or not, does the pricing look good?

Can't tell why the other quotes I have gotten are 2000-3000 more than this guy. He claims to be Carrier authorized dealer, but I can't find him when I search for dealers on Carrier's website. To this, he says that they need to pay to be on Carrier's website. It's an extra marketing cost that they don't want to incur and thus are able to pass on those savings to customers. I can't argue about their price, it is by far the cheapest. Only thing is, I don't have any way of knowing how their install quality is. They do seem to have glowing reviews on Angies list as well as Customerlobby.com

KG

How were you able to figure out when the OP's house was built? Whether it was built 30 years ago or last week it doesn't matter if a load calculation is done. I know you think load calculations are a waste of time and money. I just cringe when I hear someone sizing an AC condenser based on 1 ton per 500 sq. foot in a very humid climate.

I read the post. The OP posted his location in his second post, first line.

In the south it is possible for large glorious windows because 6 months of the year 'sometimes' the weather isn't so extreme. Windows are a huge load and it depends on the structure. I don't think load calculations are a waste of money when they are used properly. But some how people think that a load calculation is an official calculation when in 'most' cases I've seen and performing these over the years I see first hand how they can be used wrongly.

If you have a system that is already sized and has sat at a location for 15 years or longer... what makes you think it is not sized properly? It's easy.... just look at the utility bills, find out what set point temperature is. The utility bills will tell you a better story and this story is told in under 10 minutes. Now if I see mismatched equipment or big discrepancies in sizing (in person not chatting in a forum board) I would recommend a heat load calculation. But this adds to the cost. I don't do them for nothing.

As far as I know you can still buy and install an 80% efficiency furnace in any part of the country.

The reason you can't buy a "13 SEER" condenser in Katy, Texas is because your local distributor does not want to stock them.

No again. It's against the law to 'knowingly' install them. If reported I would likely be fined by TDLR maybe the EPA as well and possibly lose my HVAC license.

EPA / DOE? who cares... it's the government. What difference does it make?

some people like to squabble just for the sake of squabbling. If I had a nickel...

KG,

As far as two stage AC for your area goes I would say it's a borderline decision for you. I know Dallas area can be humid at times, just as much as it can be dry during the winter in Houston sometimes. It really comes down to what you want.

Given your location of Dallas, Texas area I think a properly sized and well installed single speed AC would work fine. You could add the 80% variable speed 2 stage gas furnace and throw in a dehumidification thermostat and that may be all you really need.

A two stage AC works better on dehumidification, but for the little time your location is under high humidity you may not notice the difference.

If you plan to stay in this home and eventually zone it to reduce waste and increase comfort, then I would opt for the (communicating system) 2 speed AC with 2 stage variable speed gas furnace.

Austin,

The DOE has proposed raising the minimum furnace AFU to 92%. Here is one article that talks about it. The proposal back in 2015 was withdrawn because of the cost burden to install a condensing furnace in old homes.

I am amazed that you can figure out the age of a house based that it is located in Plano, Texas. You are really good.

KG,

Can you post the quotes you have received from the Carrier dealers? You need to list all the model numbers and what type of installation they plan to do (replace line set, etc.). This may show why there is a big discrepancy in pricing. I would suspicious of a quote that is much lower than others for the same equipment and installation.

I don't buy the story that it costs a lot of money to be listed on Carrier's web site as an authorized dealer. Perhaps others can comment on this.

Thanks Austin and mike_home.

mike_home, I already posted the actual quote including model #'s from the guy who is quoting Carrier systems:

2 stages for $7900:

http://www.greenleafair.com/#xl_xr_page_4ton-infinity-carrier

I think this is the Infinity controller and would provide the communicating features?

And the single stage for $6300: leaning towards this one, but it does not have variable speed furnace:

http://www.greenleafair.com/#xl_xr_page_4ton-carrier

Nobody else is even close to these quotes, others are from 7867 to 9500 for single stage.

Let me know what you guys think in terms of pricing for the 1 stage.

I am amazed that you can figure out the age of a house based that it is located in Plano, Texas. You are really good.

Well I have to confess I cheated and consulted with magic 8 ball... he could only give me a rough estimate and so I went with it.

Magic 8 ball: National average replacement equipment age = 15 years. House must be at least 15 years old.

Building efficiencies of 2000 are no where near what they are today. Obviously the house may have been built in the 1990's or later... but this is magic 8 ball land.

Energy Star via the good ole EPA has the north listed at 95% and the south at 90% to be able to use the Energy Star classification. This became effective in 2013.

Furnaces Energy Star label requirements 2013

KG,

Price matters not one bit if the system is not installed right. Any amount you save on installation can quickly evaporate if problems ensue. While paying a higher price isn't a guarantee either... you have to go with your gut not just price alone.

Look at the whole picture. What is the real difference not considering price... take price out of the equation. Who is doing the work of the installation?

An installer? A tech? A licensed HVAC contractor that owns the company?

Realize a licensed HVAC contractor, has much more time and skill invested. < that is what you should be paying for regardless of price... because they are less likely to blow away with the wind once volume slows to nothing.

Choose carefully.

Austin, first, you were spot on in terms of the year my house was built in 2000 and we do have 32 windows. On pricing, understood regarding installer quality, but price not withstanding, there doesn't seem to be that much on paper separating the lowest price guy from the others. All seem to be licensed, bonded and have good reviews on AL and got their 2016 Super Service awards. The lowest quote (Green Leaf Air) also claims to be Carrier authorized dealer, has glowing reviews on Angies list (49 A's and 1 B of 50 reviews) and customer lobby: https://www.customerlobby.com/reviews/43191/green-leaf-air/.

Here is what's included in the prices from Green Leaf: $6300

-Carrier® ComfortTM - 4 Ton, 16 SEER, Residential Air Conditioner

Item: 24ABC648A003

-Carrier® ComfortTM 80% AFUE 90,000 Btuh Multipoise Gas Furnace

Item: 58STA090---1--16

-CASED MULTI-POISE A COIL;ALUM

Item: CAPMP4821ALA

-36 x 36 22 Gauge Welded Drain Pan

Item: DP-36x36-22GW

-M&M - MP-DFP2025R6 - 20" x 25" Dual Filter Plenum with 1-1/2" Liner

R6

Item: PL20X25X36-R6

-M&M - P6191/2193/436R6F0 - R6 No Flange 26 ga. Plenum 19-1/2" x

19-3/4" x 36"

Item: PL191/2X193/4X36-R6

-Safe-T Switch

-Disconnect

-Whip

-Freon Line Clean Up

-Duct Sealing With Duct Tape, Zipties, and Mastic for 100% Sealing

-Unit Sealing With Mastic

-10 Years Warranty on Parts

-5 Years Warranty On Labor

The 2 stage quote is $7900, only difference from the above will be:

58CVA090 furnace and 24ANB748A003...

What filter will be provided? See if he will include a 4 inch media filter in the price.

I still think a 3 ton condenser for the first floor (1800-1900 sq. feet) in a humid climate would be sufficient. I also think a 70K furnace would keep you very warm in your moderate climate.

The two stage should have a different controller as well as the equipment changes you mentioned.

Have them install this stat with the 2 stage AC and furnace. If you are comfortable with them as a company I would opt for the 2 stage option with this thermostat.

I don't offer Carrier in my area, because there are better options available to me and my customers. But different locations can change things in retrospect to part availability when a system breaks down etc.

With that said... the two speed equipment & included with this Thermostat is the better option among the choices provided.

PS: don't change anything in regards to sizing. Those windows are a heavy heat load in the Texas sun.

Yes, 4" media filter will be provided. If I opt for the 2 stage, the Carrier Infinity Touch Control wifi thermostat will be provided (SYSTXCCITC01-A).

In terms of brand (Carrier vs Lennox) reliability and parts availability and parts pricing, is one better than the other. I am hearing both these brands require a licensed professional to be able to buy the parts (so a HO cannot buy the parts directly). Does this lead to higher parts pricing? I am also mixed opinions about Lennox taking their sweet time to fulfill replacement/spare parts orders. Some reviews mention the same thing about Carrier. I certainly would hate to wait on parts to arrive for repairs, especially if the ac is non-functional.

For e.g. : http://www.garagejournal.com/forum/showthread.php?t=187056&showall=1

opinions are all over the place.

While this site: https://asm-air.com/hvac/lennox-vs-carrier-furnace-review/

seems to suggest the following:

Probably the biggest disadvantage of purchasing a Lennox furnace is how hard it is to find replacement parts, and these parts are expensive and don’t last as long as competitors.

Lennox offers a 10-year warranty on all parts, but the problem is that it can take days (sometimes weeks) to get the proper replacement part.

The Carrier series furnaces are less likely to break down, in our experience, and if they do it is so much easier to order replacement parts. Usually you can get a Carrier replacement part within hours, which is nice if you’re toughing out a winter in Bozeman, Montana.

Carrier also offers a 10-year warranty on all parts, but once your warranty is up their parts are also more affordable.

In the end, as far as reliability and repairs are concerned, the Carrier far outperforms the Lennox series furnace.

Everything you state in regards to parts is pretty much true. Manufacturer's create this by their own greed in using proprietary parts... they all do it to one extent or another.

So you would think they would have a nearby factory with any part you want? not so, especially if the factory is located in another state away from the distributor / supply warehouse.

Between all of the major manufacturer's in regards to parts and part availability the best in part availability is Goodman / Amana / Daikin -- they aren't perfect unless considering them against the others. I don't know if that is just a Houston thing or not, but that is my experience.

Reliability and repairs: mixed bag for the most part. Most repairs I make on units I install are like dumb repairs... like a defective switch from factory, Condenser fan motor making excessive noise etc. These kinds of problems happen around 2 times out of every hundred units I put in... so it's very low.

I have installed Grand Aire which is more or less Carrier or if you prefer ICP. These have a perfect rating so far with me - not a single failure of anything and I have been offering these since 2014.

Heating and Air Conditioning is not a DIY job. I wouldn't recommend that, a house is the most expensive asset you own.

I read some of the postings on the web site you provided. It seems strange how he bashes Lennox but we will sell this furnace to anyone who wants to buy it.

I also found it interesting that he rates Day Night as the best value furnace. He implies that Day Night and Carrier are the same furnace because they are made by the same corporation. We know Chevrolet and Cadillac are both made by GM and have many common features. But do we think all the components inside are virtually the same?

I have been told Lennox uses proprietary parts which makes repairs more difficult.

You should take a survey of what brands are popular in your area. Where I live you can see very few Goodman and Lennox. There is no Day Night dealer within 100 miles of my zip code so even if I was convinced it was a great value I would night buy it.

Many repairs are the result of poor installation of oversized equipment. But unfortunately the furnace manufacturer gets the blame for poor reliability. The manufacturers are not totally innocent. There are models out there where corners where cut to keep prices low and efficiency high. But if you choose a model that has been available for several years you can avoid most of the design issues.

I agree the brands comparison with HVAC is far more complicated than that of cars. In some cases the the internal components are exactly the same, only the outside badge is different. In other cases the equipment is very similar but there are some important differences.

HVAC equipment also depreciates. You are correct that spending a little more money can get you more efficient equipment. But then again someone can takes it to the extreme of buying equipment that can reach a 20-22 SEER rating. That may not be the best investment.

Ironically the lowest cost cars tend to get the best gas mileage. Yet people buy cars based on their features. The gas mileage is usually not the most important thing in the car decision process. Can you imagine someone walking into a car dealership and asking for a quote for a car that gets 28 miles to the gallon, and how much additional would it cost to upgrade to a car that get 30 miles to the gallon?

HVAC equipment doesn't depreciate... it dies.

There is no 'USED' HVAC market. 99% of all equipment replacements I do result in the HVAC equipment be retired to the junk yard.

There is a 'USED' car market.

Sorry it is pointless to compare the two in this sense.

If you install new HVAC equipment in a rental property you would be allowed to take a depreciation as a capital improvement. There are people who try to buy and sell used HVAC equipment but I agree it is not worth installing even if it were free.

I don't understand why you are arguing about depreciation. The point I was trying to make is all HVAC equipment made by the ICP corporation may or may not be the same. I tried to come up with a simple analogy whichi could be understood by people who are not HVAC subject matter experts. But as you have pointed out no analogy is perfect.

Hopefully the OP will understand that at the end of 3 years and/or 1000 hours of operation he can't trade in his AC as a down payment for a new AC system. If he does I am truly sorry for posting something that could lead him to that conclusion.

LOL. Taking a depreciating claim on Taxes is merely a way to reduce the amount paid on Taxes. It really isn't the same as a depreciating value. Once installed in one property there is no 'real' value to the unit. Removing it and the manufacturer warranty goes bye -bye.

A landlord takes a depreciation on the building over a number of years. I'm not a CPA so it might be 30 year depreciation cycle. So at the end of the depreciating cycle is the landlord looking to sell the property now for the depreciated value he has enjoyed on reducing his taxes?

No. A house appreciates in value. Obviously certain things can affect this and under adverse times the landlord or home owner may be underwater in what they owe on the house versus what they can sell it for.

I use a car comparison for certain things to help people understand various things... but for the most part a car is a poor comparison to an HVAC system.

I guess you are right. Nobody is going to buy this on ebay.

well people buy junk all the time and get swindled. You noticed from that listing that the seller claims the unit still has a warranty?

Wrong. Then on top of this it's a 13 SEER unit. It would be illegal to install this in the south. The only reason things like this exist is there are those who do this stuff as a hobby, unlicensed, uninsured. They call in sick from their regular job do a side job for cash and then blow away with the wind.

A year to 3 years later I get a call about an AC not working. Find out the system wasn't installed properly, check warranty info and the warranty is no good due to being moved from original installation location.

Then the home owner either lies to my face or admits how foolish they were.

On the 2 stage units, find out what the coils are made of, I bet aluminum. The upper end Trane and AS single speed units still use copper. IMHO, avoid unit if it's with aluminum coils per local folks doing AC in our new house build with 2 units. Aluminum coils seem more problematic. Granted a lot of info on corrosion with the copper but if properly set up, more of a nonissue. Lastly, most here prefer single speed units. Simple proven design that is not so complex and works. Parts availability it not an issue.

Trane and AS all use aluminum in and out for their coils, so I don't know where you are getting your info from.

As far as problems with aluminum sure their can be, just as much as there can be problems with copper tube and aluminum fin coils.

ANY copper tube coil made in the last few years is not likely to stand up.

I'll tell you why... it all comes down to economics.

If a manufacturer can cut material costs in one unit. (they are all bean counters.) They look at how many units they sell. Trane & AS are not the same companies they once were... bought out by IR several years ago.

The number of units they sell per year is fairly consistent depending largely on the health of the real estate market. If a manufacturer sells 1 million units. (When I say unit I am talking one piece of equipment: Like coil, condenser or furnace.)

So if you sell 1 million units every year and competition is fierce... which it is by the way... how could you make more money WITHOUT raising prices that much?

EASY: Cut material cost: the amount of material used to make the 'unit'.

Copper is a high cost material. Make it paper thin and you may cut $10 out of the material cost to make the 'unit'.

$10 isn't much... but if you take that and multiply it by 1 MILLION... how much do you have?

There is NO SUCH thing as an AC that never breaks down. NO name brand is perfect. NONE. You either listen to the truth I laid out above or you don't it doesn't matter to me. I know what I know from over 20 years of doing actual work... not sitting around and just blogging about it.

You're right, they ALL break sooner or later and there's nothing perfect. I don't install or sell HVAC equipment. However, the information I've obtained comes from a pretty wide variety of sources who DO SELL and SERVICE HVAC equipment and all close friends whose experience when all told adds up to well in excess of 100 years of experience in sales and SERVICE of HVAC units. I've got nothing to gain by posting and just passing along what I deem to be solid information in hopes that if nothing else, folks will consider, learn and make an informed choice. My resources all agree on one thing with HVAC and that's KISS: Keep It Simple Stupid. Simple one speed unit properly sized and installed per a Manual J and maintained according to specs. This type of system I am told will MOST likely give us the best option for trouble free service. But again, they all sure break. They absolutely shy AWAY from the 2 speed high dollar units and the various "electronic add ons" as they put it to ensure efficiency. Kind of like the iPhone market in a way, there's always better. What's great today is going to be OLD news next year. The SMART system of today will be next years DUMB system and you're stuck with it.

The biggest thing I've taken away from speaking to them is that it MUST be sized properly and INSTALLED properly. Oversized equipment = problems as does undersized equipment. Spend the coin upfront, get a Manual J and make NO assumptions on what the right sized equipment should be. IF company A recommends say a 3 ton system, ask why and how they came to that decision? Company B may recommend something else. When the day is done no matter WHO you buy the equipment from, you've got to live with it. Research the companies, the SWEET smell of a GREAT deal may turn SOUR after the sale when you can't get service or parts in the middle of July when the humidity is high and the temps are approaching 100 degrees, been there and done that. It's all about the service AFTER the sale and their experience. They may sell the latest and greatest equipment, but if a company doesn't invest in the training and proper equipment to service it, when it breaks you are stuck like Chuck.

Here is a report discussing how formicary corrosion occurs on copper coils. One of the things that may be contributing to the problem in today's coils are made from recycled copper versus coils made 30 years ago were made from virgin copper. Aluminium has other problems in addition it does have the same thermal resistivity as copper.

You are right the simpler the machine, the less things there are to break. But the problem is a single speed furnace is often marketed as a low end product. The market share of multi-stage variable speed equipment continues to grow.

Your iPhone example is interesting. An iPhone is very expensive, can crack if dropped on a hard surface, and has software problems. On the other hand an old style flip phone doesn't have these problems and is much cheaper. Yet you know which phone people line up to buy at the store each year.

Thanks for the report, will have a read. You hit the nail on the head here " But the problem is a single speed furnace is often marketed as a low end product. " Marketing, since it is NEWER, it's GOT to be better right? The marketing/sales departments are PUSHING the "perceived" latest and greatest. And just like the iPhones, people want the latest and greatest. Same thing pretty much applies tothe "SMART HOUSES". Technology changes at such a rapid pace, today's "SMART HOUSE" is tomorrows OLD and LOW tech.

I'm good, just give me some simple solid equipment, hard wired security cameras with POE. Lot of these new tech companies are pushing this "high technology and security". If someone opts to break into our house, well they'll deal with the 3 Glocks I have in various locations as well as 4 Remington 870 12 Gauge Police Special shotguns. When they leave, it'll be in a body bag. Maybe I'm just old school.

You know, I would REALLY like to see a CONTROLLED test done between a single speed "low end system" and the newer latest and greatest "dual speed systems" set up in identical homes for a true comparison. Houses would need to be identical in every way to get an accurate comparison and the test run say over a couple of years, all inclusive of service calls, etc. I think the results would be pretty interesting!

Pensacola,

Ok in summer time you know what the odds are the house I go to will be a single speed KISS system that is broken?

99.9% off all HVAC systems out there for residential are currently KISS systems. If they are so reliable why is it these kinds of systems are the ones I am repairing? If I had a nickel for every 2 speed AC system I've worked on I would be broke.

You can talk all day long, consult with folks who do more talking and at the end of the day you are no better off then if you hadn't consulted with anyone.

Thanks for your opinion.

So which system and installer did you decide to go with? Any install/post install comments?

"You know, I would REALLY like to see a CONTROLLED test done between a single speed "low end system" and the newer latest and greatest "dual speed systems" set up in identical homes for a true comparison."

OK, this is not a perfectly controlled study, but a reasonable one with the practical limitations of the real world. It is also a bit dated. There may be better and more recent studies out there. I think that you will find it interesting.

https://buildingscience.com/documents/bareports/ba-0214-conditioning-air-in-the-humid-south-creating-comfort-and-controlling-cost/view

You might find the University of Central Florida a resource for AC. A few years ago they did some great studies on cool roofing systems.

A nice feature of copper is that it is naturally antimicrobial. Aluminum, not so much. With copper, the chances of DSS are minimal.

I purchased a RUUD 2 stage ac. Biggest mistake ever. It did not dehumidify my home and my electric bills doubled. The ac is only 1 year old and leaking water in the drain pan. The attic handler is sweating. The guy who installed it will not return my calls. I cannot find one contract who can figure out what is wrong with the unit. No one knows how this system works including Rheem. Rheem's customer service is awful. The name RUUD fits them because their service reps are rude when you contact them for help.

Rheem have specialist installers who can help you. Look for one on their website. Sounds like a bad original installation. Anything (everything) can be fixed.

Sure smells of a bad installation to me as well.

thanks all, your comments were very helpful. In the end, cost was a major factor, so I compromised a bit and got the (slightly) higher end, but still single stage system.

Here's what I got:

Carrier 24ABC648 4ton 16SEER with 58PHB090 furnace and 5 ton coil CAPMP6021.

The higher tonnage coil, according to my installer is to achieve overall 16 SEER. If I went with the 4 ton coil, it would be 15 SEER.

Also, I went with this installer over the previous installer (the one who quoted $6300 system) as he took the time to explain, has been doing Carrier for 20+ years and I have seen their trucks many times in my community, and also did a Manual J.

Hope this helps others.

I got this for $7300, more than my original quote, but upgraded furnace, system and coil for the extra grand, including Nest T-stat.

KG

As long as you're happy and the system works well, that's all that really counts!

Hi KG,

I am also working with Green Leaf Air to replace my HVAC units. Just want to check if you are happy with the units and the overall installation as this will be a great data point to make my decision.

I just skimmed through the comments here and was a bit disappointed about the strategies for using 80% AFUE in Texas and other warm climates. What justifies sending 20 percent of your fuel out the exhaust? That is your money being wasted and methane going into the atmosphere. Why not go high-efficiency and lower your BTU input? From what I understand, the 80% systems are builder-grade, get in/get out products. They are cheap to install but not environmentally nor operationally cost conscious.

Nathan, if your heating bill for the year is $500 with an 80% furnace, a 92% furnace will net you $65 annually if that furnace actually hits the mark, but it is probably oversized so it won't. The lifetime cost of owning and operating the equipment (equipment + fuel) should include repair and maintenance which is probably higher with the more sophisticated equipment. Then you have the opportunity cost for the early investment which could be put to better air sealing and insulation, for example.

Just to keep the arithmetic simple, let's assume a 15 year lifetime. Ignoring everything but equipment and fuel, the 92% furnace would have to cost no more than $975 more than the 80%. Air sealing and insulation will net you more. Then there is the problem that many or most people in the South have their furnaces in the attic. If the furnace is condensing, the drain line has to be prevented from freezing.

If you must have a more efficient furnace to gain efficiency on the cooling end, or more comfort, so be it. It may be, however a poor investment on the heating end. If I had to for the cooling side, I go for the more expensive furnace. Having experienced the humidity removal capabilities of modulating compressors and blowers combined, I don't want to go backwards.

Nathan,

I doubt you would hit even $500 gas bill where I am in Katy, Texas for the simple reason I am on electric heat and I don't come anywhere close to $500 electric bill. Last winter was colder than normal and I might have brushed $300 for the whole winter season.

A furnace rated above 80% efficiency (for heating) for my area are simply not worth the expense, the money is better put toward a more energy efficient air conditioner.

Air conditioning for my market (Katy, Texas) can be as much as 10 months of the year. It's more common to replace furnaces here in the summer than the winter, if you need some perspective. (IE: the AC can not cool without the furnace, but the furnace can heat without the AC.)

What justifies sending 20 percent of your fuel out the exhaust? 20% of what? If you spend $300 for heat, that's a whopping $60 a season. x 20 = $1200 that's if you could find a furnace 100% efficient.

But you won't do that... best case is 97% efficiency. So you will save $51 a season using the above logic. These furnaces come at a premium. You will never recoup your so called waste.

90% you save a whopping 10%. = again $300 for heat. You save $30.

As pointed out by ionized there is the possibility of condensate water freezing. However, even this is not a problem in my area (It's almost always above freezing here).

I have a long standing customer of mine with a condensing furnace. (Installed by builder of the home). There has never been an issue with condensate line freezing. (It has clogged up though, with slime) so there is yet another expense that you wouldn't have with a non-condensing 80% furnace.

What you think you are going to save, depends heavily upon the climate in which you live. Low use appliance simply will not recoup what you think you are wasting.

Austin, is it true to say that any gas furnace that you install along with cooling will be oversized with respect to heat output?