Sweet Spot For SEER Rating

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LifeIsGood
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Location: Atlanta, GA

Sweet Spot For SEER Rating

Post by LifeIsGood »

I'm helping my daughter replace her HVAC system. The dealer she has decided to use has quoted for 3 different SEER rating systems.
16 SEER = $8,600 15 SEER = $7,500 14 SEER = $6,400.
These numbers are for separate upstairs and downstairs Trane systems including furnaces and a bit of duct work revision.
I know there is a point of diminishing returns on increasing SEER rating and their associated costs. She lives in Atlanta, GA if that makes a difference.
What would give her the most "bang for the buck" in selecting a new system?
finite_difference
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Re: Sweet Spot For SEER Rating

Post by finite_difference »

What kind of system is it? For example heat pump or forced air natural gas + AC?

If you get a heat pump then I’d get one that operates efficiently down to 32-37F or so. Atlanta gets that cold right? But you mention a furnace.

Here’s how to calculate the savings: https://georgebrazilhvac.com/blog/16-se ... ent-air-co

Eye-balling it, probably SEER 14 is good enough but if you plan to stay in the house for a long time then go SEER 15?
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jebmke
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Re: Sweet Spot For SEER Rating

Post by jebmke »

Are there any other differences other than SEER? Are all the units two-stage compressors?
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shuresm7b1
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Re: Sweet Spot For SEER Rating

Post by shuresm7b1 »

I got a 4 ton 18 seer for $12,800 and my 2600 sq ft house has bills of $120 a month now compared to $250 with my 12 seer. It all depends on how long you will live there.
wilked
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Re: Sweet Spot For SEER Rating

Post by wilked »

1. List the models here
2. What is a real range of years she will live there? What is the best guess for years of ownership?
3. Can you describe the property? SFH, year built, sq ft, etc?
livesoft
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Re: Sweet Spot For SEER Rating

Post by livesoft »

We live in a similar climate and have a 3000+ sq ft McMansion. We have Trane (aka American Standard) systems, one for upstairs and one for downstairs. We pay about $250 a year for heating and $450 a year for cooling. Our AC systems date from 1993 and 2004. They are 13 SEER. I am going to get a 14 SEER unit to replace the 1993 unit. I see no reason to pay for more SEER.

You can do our math: $250 + $450 = $700 or we pay under $60 a month for heating and air conditioning.
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pochax
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Re: Sweet Spot For SEER Rating

Post by pochax »

here is a cost savings calculator for you to put your numbers in:
https://www.acdoctor.com/energy-calcula ... code=07481

last year we replaced our 20 year old HVAC unit with a 5-ton 14 SEER. the cost savings with a 16-SEER was not worth the extra cost of the unit. i saw a 30-40% reduction in our summer AC cost with the replacement (plus it's a lot quieter now) but to be expected after a 20-year replacement.
lazydavid
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Re: Sweet Spot For SEER Rating

Post by lazydavid »

I would pay either of those incremental price increases to go from a single-stage to a two-stage or variable condenser. I would not pay them if they were identical other than SEER rating.
Valuethinker
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Re: Sweet Spot For SEER Rating

Post by Valuethinker »

LifeIsGood wrote: Mon Feb 26, 2018 6:43 am I'm helping my daughter replace her HVAC system. The dealer she has decided to use has quoted for 3 different SEER rating systems.
16 SEER = $8,600 15 SEER = $7,500 14 SEER = $6,400.
These numbers are for separate upstairs and downstairs Trane systems including furnaces and a bit of duct work revision.
I know there is a point of diminishing returns on increasing SEER rating and their associated costs. She lives in Atlanta, GA if that makes a difference.
What would give her the most "bang for the buck" in selecting a new system?
There is an HVAC Forum which is mentioned here (if you google it). I don't think their posting rules allow pricing comparisons, but otherwise the people are apparently very knowledgeable and helpful.

There's pretty much a consensus on this Forum that a 2 speed unit gives significantly more comfort than a single speed unit. That's key.

If I was in a position to aid financially the decision, I would spot for the highest spec - $2100 is just not that much over the lifetime of someone in a house, and utility rates don't tend to go down. But I would definitely lobby for the SEER 15 over the 14, in any case.

https://en.wikipedia.org/wiki/Seasonal_ ... onditioner

Roughly speaking, the improvement in energy consumption should be (16-14)/14 as a per cent, I think (about 14%). From 14 to 15 about 7.1%.
Topic Author
LifeIsGood
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Re: Sweet Spot For SEER Rating

Post by LifeIsGood »

More info about the house:
Presently forced air natural gas + AC
~ 2675 sq ft of finished space
Built in 2003
As best I can tell researching the quote, all the compressors are single stage.
She expects to stay in a house 10 more years.

Here's the details of the quote:
SEER 16 System
Downstairs AC System Trane XLi16 Series deluxe 2.5-ton AC model # 4TTX6030
Trane Comfort Coils 4TXCB003
2-stage variable speed gas furnaces with high efficiency ECM motors TUD2B060A9V3
Upstairs AC System Trane XLi16 Series deluxe 3-ton Ac model 4TTX6036
Trane Comfort Coils 4TUDB004
2-stage variable speed gas furnaces with high efficiency ECM motors TUD2B060A9V3

SEER 15 System
Downstairs AC System Trane XL14 Series deluxe 2.5-ton AC model # 4TTR4030
Trane Comfort Coils 4TXCB003
2-stage variable speed gas furnaces with high efficiency ECM motors TUD2B060A9V3
Upstairs AC System Trane XR14 Series deluxe 3-ton Ac model 4TTR6036
Trane Comfort Coils 4TXCB004
2-stage variable speed gas furnaces with high efficiency ECM motors TUD2B060A9V3

SEER 14 System
Downstairs AC System Trane XR14 Series deluxe 2.5-ton MODEL 4TTR4030
Trane Comfort Coils 4MXCA030
Gas furnace MODEL TUE1A060A936
Upstairs AC System Trane XR14 Series deluxe 3-ton system MODEL 4TTR4030
Trane Comfort Coils 4MXCA030
Gas furnace MODEL TUE1B060A936

Sounds like she needs to get a quote for 2 stage condenser.

Thanks again everyone for your feedback.
CppCoder
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Re: Sweet Spot For SEER Rating

Post by CppCoder »

livesoft wrote: Mon Feb 26, 2018 7:46 am We live in a similar climate and have a 3000+ sq ft McMansion. We have Trane (aka American Standard) systems, one for upstairs and one for downstairs. We pay about $250 a year for heating and $450 a year for cooling. Our AC systems date from 1993 and 2004. They are 13 SEER. I am going to get a 14 SEER unit to replace the 1993 unit. I see no reason to pay for more SEER.

You can do our math: $250 + $450 = $700 or we pay under $60 a month for heating and air conditioning.
To what temperature is your thermostat set summer and winter? I also live in the greater Houston area, and my AC bill is significantly larger than that with a relatively new, higher SEER system than yours. For comparison, my house is also in the 3000+ sqft range, where the + does not extend to above 4000 sqft.
lazydavid
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Re: Sweet Spot For SEER Rating

Post by lazydavid »

Thanks for posting the specifics.

The XLi series is a 2-stage, while the XR is single-stage. The top two packages also have a better quality furnace/air handler unit than the 14 SEER one does. Both units are 80%, the legal minimum for efficiency, but since she's in Atlanta, this doesn't bother me much. But the 2nd stage on the higher end unit would be even more important in a moderate climate, since it'll almost always run on the lower setting when there is a call for heat.

I would absolutely cough up the extra $2200 for the 16 SEER package. You get both a better efficiency rating along with 2-stage operation for both heat and AC, along with better quality equipment in general.
Beach
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Re: Sweet Spot For SEER Rating

Post by Beach »

livesoft wrote: Mon Feb 26, 2018 7:46 am We live in a similar climate and have a 3000+ sq ft McMansion. We have Trane (aka American Standard) systems, one for upstairs and one for downstairs. We pay about $250 a year for heating and $450 a year for cooling. Our AC systems date from 1993 and 2004. They are 13 SEER. I am going to get a 14 SEER unit to replace the 1993 unit. I see no reason to pay for more SEER.

You can do our math: $250 + $450 = $700 or we pay under $60 a month for heating and air conditioning.
How do you know specifically how much your AC/Heat is costing you? How can you break down your KW/gas(if applicable) usage to determine this? Not attacking, just want to know.
livesoft
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Re: Sweet Spot For SEER Rating

Post by livesoft »

Beach wrote: Mon Feb 26, 2018 3:19 pmHow do you know specifically how much your AC/Heat is costing you? How can you break down your KW/gas(if applicable) usage to determine this? Not attacking, just want to know.
In the winter we don't use AC, so we can take the lowest monthly electric bill in winter to be the monthly value of non-AC electric use. Anything above that value I can call AC electricity. Example: Our last 3 electric bills average $43.21.

In a similar way: In the summer we don't use heat, so we can take the lowest monthly natural bas bill in summer to be the monthly value of non-furnace natural gas use. Anything above that value I can call furnace natural gas cost. Example: Gas bills from May to November averaged: $24.49 which covers clothes dryer, water heaters.

I hope that makes sense, but if not please let me know.
Last edited by livesoft on Mon Feb 26, 2018 4:32 pm, edited 1 time in total.
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livesoft
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Re: Sweet Spot For SEER Rating

Post by livesoft »

CppCoder wrote: Mon Feb 26, 2018 1:08 pmTo what temperature is your thermostat set summer and winter?
78 deg in summer. We have ceiling fans over every bed and in the family room, too.

68 deg and 70 deg in winter.

Sometimes we manually override the above temps.
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Topic Author
LifeIsGood
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Re: Sweet Spot For SEER Rating

Post by LifeIsGood »

David, I could be wrong but I believe the XL18i is the lowest SEER system that has 2 stages.

Image
lazydavid wrote: Mon Feb 26, 2018 2:11 pm Thanks for posting the specifics.

The XLi series is a 2-stage, while the XR is single-stage. The top two packages also have a better quality furnace/air handler unit than the 14 SEER one does. Both units are 80%, the legal minimum for efficiency, but since she's in Atlanta, this doesn't bother me much. But the 2nd stage on the higher end unit would be even more important in a moderate climate, since it'll almost always run on the lower setting when there is a call for heat.

I would absolutely cough up the extra $2200 for the 16 SEER package. You get both a better efficiency rating along with 2-stage operation for both heat and AC, along with better quality equipment in general.
lazydavid
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Re: Sweet Spot For SEER Rating

Post by lazydavid »

LifeIsGood wrote: Mon Feb 26, 2018 5:06 pm David, I could be wrong but I believe the XL18i is the lowest SEER system that has 2 stages.
Appears you're right. I was looking at the cutaway diagram in the brochure which depicted a two stage compressor, and didn't notice that just the XL16i. is single-stage. That does change the calculus somewhat. I'd still spend the $1100 for the two-stage furnace without question. The decision point then becomes is it worth another $1100 to switch the condenser out for a higher-quality unit and gain one more SEER in the process. I could go either way on that.
denovo
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Re: Sweet Spot For SEER Rating

Post by denovo »

LifeIsGood wrote: Mon Feb 26, 2018 6:43 am I'm helping my daughter replace her HVAC system. The dealer she has decided to use has quoted for 3 different SEER rating systems.
16 SEER = $8,600 15 SEER = $7,500 14 SEER = $6,400.
These numbers are for separate upstairs and downstairs Trane systems including furnaces and a bit of duct work revision.
I know there is a point of diminishing returns on increasing SEER rating and their associated costs. She lives in Atlanta, GA if that makes a difference.
What would give her the most "bang for the buck" in selecting a new system?
It becomes a simple question of math once you get a good ballpark idea of how much heat and air.conditioning her house uses and the expected lifetime of a unit (10-15 years is a good rule of thumb).

Also, some utilities will give you a rebate for purchasing units with higher SEER ratings which will affect your calculations.
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denovo
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Re: Sweet Spot For SEER Rating

Post by denovo »

livesoft wrote: Mon Feb 26, 2018 4:09 pm
CppCoder wrote: Mon Feb 26, 2018 1:08 pmTo what temperature is your thermostat set summer and winter?
78 deg in summer. We have ceiling fans over every bed and in the family room, too.

68 deg and 70 deg in winter.

Sometimes we manually override the above temps.
Holy moly, I'd melt at 78. I put that sucker at 71 in the summer.
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Topic Author
LifeIsGood
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Re: Sweet Spot For SEER Rating

Post by LifeIsGood »

Just got a quote from the dealer for the SEER 17 2 stage system installed upstairs and SEER 16 single stage system downstairs- $9,100 total. That's $500 more than the single stage SEER 16 system . It would be an additional $600 ($(9,700) to do SEER 17 2 stage upstair & down.

lazydavid wrote: Tue Feb 27, 2018 5:03 am
LifeIsGood wrote: Mon Feb 26, 2018 5:06 pm David, I could be wrong but I believe the XL18i is the lowest SEER system that has 2 stages.
Appears you're right. I was looking at the cutaway diagram in the brochure which depicted a two stage compressor, and didn't notice that just the XL16i. is single-stage. That does change the calculus somewhat. I'd still spend the $1100 for the two-stage furnace without question. The decision point then becomes is it worth another $1100 to switch the condenser out for a higher-quality unit and gain one more SEER in the process. I could go either way on that.
JohnF
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Re: Sweet Spot For SEER Rating

Post by JohnF »

Not that you asked, but 5.5 tons of AC for 2,675 square feet seems grossly oversized. I’m cooling 3,600 square feet in Atlanta with 3.5 tons. Smaller units would be cheaper, quieter and run longer removing more moisture.
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unclescrooge
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Re: Sweet Spot For SEER Rating

Post by unclescrooge »

JohnF wrote: Tue Feb 27, 2018 7:48 pm Not that you asked, but 5.5 tons of AC for 2,675 square feet seems grossly oversized. I’m cooling 3,600 square feet in Atlanta with 3.5 tons. Smaller units would be cheaper, quieter and run longer removing more moisture.
Wouldn't the size of the system depend on the elevation and max summer temperature?

As an example, I got 11 quotes for a new HVAC at my old house. Only one guy did a Manual J load test (or pretended to). Every single quote came back sized at 5 tons.

When I asked one guy, he said when it gets 110 degrees in the summer I'd be glad I had a 5 ton system.
Beach
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Re: Sweet Spot For SEER Rating

Post by Beach »

Having an oversized system leads to short cycling and inefficient cooling...Make sure its sized properly! Lots of articles on Google on how to size it properly or get a 2nd opinion. Additionally, if you happen to have spray foam insulation, it makes a difference and you can downsize it even more.
strafe
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Re: Sweet Spot For SEER Rating

Post by strafe »

The ECM blowers are worth every penny. I would rule out the 14 SEER since it does not have ECM.
2-stage A/C is a comfort feature (improved humidity control and smaller on/off temperature fluctuations) -- not necessarily all that cheaper to run.
An ECM blower already gets you much of the dehumidification benefit, and costs a lot less to run.

I would also make sure the furnace is not oversized.
Dudley
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Re: Sweet Spot For SEER Rating

Post by Dudley »

These things can be noisy (particularly scroll compressors in heat mode). I would interogate the installer on the measures he is going to take to stop vibration (particularly low frequency) coupling into the house, eg mount on vibration isolators, putting 90 degree bends in the line set, isolating the line set from building, duct isolation, etc
Trev H
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Re: Sweet Spot For SEER Rating

Post by Trev H »

I built a new home in 2001 and went with Elect Heat Pump HVAC system (Trane)... and 18 SEER.

I acted as general contractor myself... hired all the subs, ordered all of the materials, scheduled everything.. and the money I saved by doing all that work, I put part of it back into the house... and energy efficiency was one of those areas I hit with that extra cash.

17 years later and we still have that same system in and running (with some maintenance over the years)...

But also with greatly reduced utility bills for 17 years.

It is really an investment.. and probably not worth it if you were going to put it in and sell the house in 5-10 years... but if you are going to be there for the long haul... I wold highly recommend upping the energy efficiency of your home. The HVAC system is just one part of that. Insulation, doors and windows, etc...

When we first built our home - we were heating . cooling 2600 sf with this 18 SEER unit... My Elect Bills were averaging around 140.00
I also had very energy efficient electric hot water heaters (Marathon brand). Still have them too.

My Parents had a 1600 Sf frame house with a 10 SEER heat pump and they were paying nearly 2x what I was. A low SEER system, combined with little insulation, single pain windows, etc... can really hit you hard.

I am in Tennessee... just north of Georgia... it gets hotter there, so summer time cooling will be the big thing for them.

Trev H
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Toons
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Re: Sweet Spot For SEER Rating

Post by Toons »

Rheem Single Stage 15 Seer for me.
5k installed :happy
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rgs92
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Re: Sweet Spot For SEER Rating

Post by rgs92 »

15 is good with my Lennox. A/C is cheap even with a fairly big 4-BR house set at 72F all summer.
littlebird
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Re: Sweet Spot For SEER Rating

Post by littlebird »

unclescrooge wrote: Tue Feb 27, 2018 8:09 pm
JohnF wrote: Tue Feb 27, 2018 7:48 pm Not that you asked, but 5.5 tons of AC for 2,675 square feet seems grossly oversized. I’m cooling 3,600 square feet in Atlanta with 3.5 tons. Smaller units would be cheaper, quieter and run longer removing more moisture.
Wouldn't the size of the system depend on the elevation and max summer temperature?

As an example, I got 11 quotes for a new HVAC at my old house. Only one guy did a Manual J load test (or pretended to). Every single quote came back sized at 5 tons.

When I asked one guy, he said when it gets 110 degrees in the summer I'd be glad I had a 5 ton system.
Yes! I have a 5 ton unit for a ~2150 house in the Phoenix metro. It seems just right.
Valuethinker
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Re: Sweet Spot For SEER Rating

Post by Valuethinker »

rgs92 wrote: Fri Mar 02, 2018 4:35 pm 15 is good with my Lennox. A/C is cheap even with a fairly big 4-BR house set at 72F all summer.
Where do you live?
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