Carrier Infinity – choosing a system, please advise

Bordo11 · May 10, 2007

Installing central A/C in my 60s house.
I am not worry about the heat loss; my house has a radiant heating system.
The furnace heating capabilities would be just to speed up the heating process in the morning and as a back up.
The main task is a cooling system, where efficiency is not the key; the key is to have as much as comfortable air temperature, humidity control and the noise. The noise is the main factor.

A few techs came up with the 3.5T size for my 1600sqft split level in Chicago area. I was a bit suspicious about the size.
I have purchased software HVAC - Calc Residential, run the calculations, the result for 95F summer outside and 75F inside:
Total heat gain 30,200 BTUH, sensible 26,600, latent 3,600.

After reading on this site I put a system pieces together, planning to go with Infinity:
24ANA136 - A/C
58MVB060-14 -furnace
CAPMP3617 –coil
SYSTXCCUIZ01-A – control

The first thought was that the cooling capacity might be to big (24ANA1 is not available in 2.5T size), but if it is a hotter than 95F day and a few people visiting house and some kitchen, heat generation activities, the total heat gain goes up to 32,800 where the sensible heat gain portion is 28,300 BTUH. I was not be able to find any data on the sensible cooling capacity for 24ANA136, but I would assume that this size would not be too big.
The first stage of 24ANA136 has a cooling capacity of 25,800, what would perfectly benefit for the lower outside temperatures during the night and providing lower acoustical noise. This unit would also provide more precision temperature and humidity control.

I was originally going with the 2.5T Performance 24APA530, better matching size and lower noise system.
But the two stage 24ANA136, even over capacity a bit, would provide more flexible operation since it has a lower power 1st stage.

Now about the acoustical noise, since the noise is the key factor. It seems to me strange that the two stage Infinity 24ANA136 has a higher noise level than 24APA530. According to Carrier site it is 70dB and 68dB respectively. The product data sheet is showing a standard rating 73dB (high stage) and 68dB respectively. But the weighted sound level tables show that the typical octave band spectrum noise levels are actually lower by one or two dBs for the Infinity two stage A/C.
My question is, which unit is actually quieter?
My A/C most of the time would work only at a first stage.
Is this is considered good approach to design the system?

I need to place an order in a few days.
I would greatly appreciate for any advises, criticism or ideas.

Bordo

dash · May 10, 2007

Nice choice,use the search function on this site and see what other Infinity owners think of their Infinity!!

Bordo11 · May 10, 2007

Dash, thanks for your reply.
I just want to add, it will be a new installation, currently I have a window unit. The furnace unit will be in crawl space. All ductwork will be new, any sizes might be chosen. I would appreciate for any suggestion on a duct work.

1. Is it a good A/C sizing approach to have an oversized system system running on the first stage most of the time?
2. Is the 3T system really oversized, since I do not know the real sensible capacity numbers?
3. Are the system pieces are matching?

Bordo11 · May 10, 2007

I will rephrase.
My load calc. shows 30,200 total heat gain.
Is it a good sizing approach to choose a 36,000 BTUH A/C equipment (25,800 on the first stage) if my load calc. show lower?

I am worry that the system would be jumping continuously from one stage to the other, since neither one has a capacity matching with the heat gain needs.
Can some one advice please.

dash · May 10, 2007

First,both the sensible and latent btus for the equipment most be more then the load calc..

Second,many rating you will find for the equipment are at 80° indoors and 95° outdoors,so they need to be adjusted to match what was used in your load calc..

To answer your question,there will be many hours that the low stage capacity will be more then you need,like at night,milder then load calc design temperature.

A good control system ,like an Infinity,will let it start in low stage,then switch to high if needed,then cycle off.So I wouldn't worry about it switching back and forth.

novakht · May 10, 2007

I also would consider the Infinity 58UVB060 model instead of the MVB060.... you gain just a bit of efficiency which isnt a big deal in your case but the UVB rates at 95% Afue-- and qualifies for a Federal Tax Credit. ( as does your A/C)

Bordo11 · May 15, 2007

Dash, thanks for clearing things up.

Novakht, I have thought about this model, but I need a horizontal unit for my crawl space. 58UVB comes only as a vertical.

It was a day when I was needed to place an order. Unfortunately I need to reconsider my system, it was over my budged.

I have a last shot.
I want to use a little bit lower cost system:
24APA536 - A/C
58MVB060-14 -furnace
CAPMP3617 –coil
TSTATCCPRH01-B – control

My worst weather case calculations showing 30,000 BTUH.
The new choice system would be only one stage:

1. Should I still consider a 36,000 BTUH unit or go to smaller 30,000, what is actually calculations show?
2. Is furnace going to work in the two stages (speed) for cooling and provide a good humidity control if the A/C is only one stage?
3. Is it even a right thing to build a system in this way, when a furnace is an Infinity series and the A/C is Performance – single stage, non communicative? Is it going to work properly or is better to have a fully Performance series system?

dash · May 15, 2007

1. You/they need to look at the load calcs.,sensible and latent btus,then be sure the equipment selected covers both.Very important that the equipment rating be adjusted for the number of degrees below standard indoor temp. of 80° F.ACCA's Manual S addresses this.

2.It should/will be setup for 350 cfms per ton,which is better dehum. then 400,then when it needs to dehum., it will run at 80 of 350 cfms per ton.

3.It'll be just fine,not as good as the two stage,but likely far superior to anything you have l experienced.

Bordo11 · May 16, 2007

Dash, thanks, now I am getting closer to my final decision.

The last thing bothers me is the system size (cooling wise) selection.
I have done a heat gain calculation with HVAC – Calc, using worst case Chicago weather scenario at 95F summer outside and 75F inside, 113 grains of moisture, 50% rel. humidity inside.
The load calc. show 30,200 BTUH total heat gain (sensible 26,600, latent 3,600) for my 60s split level 1600sqft house.
I did not find in the 24APA536 data sheet any sensible either latent cooling capacity numbers, only a total, which is 36k BTUH.
The other extreme scenario would be when a few people visiting house along with some kitchen heat generation activities, the total heat gain goes up to 32,800 where the sensible heat gain portion is 28,300 BTUH.

I know that over sizing the A/C system is really not the good thing.
Should I still consider a 36,000 BTUH unit or go to smaller 30,000 BTUH

Sorry for so amateur questions in this forum. The HVAC – Calc makes only Manual J, I do not know how to perform your suggested "below standard indoor temp. of 80° F.ACCA's Manual S addresses this". Would not be enough only Manual J with worst weather case numbers?

diynot · May 16, 2007

That's a good question. I have also wondered if you are near a capacity, slightly over, whether you should round up and get the bigger system or round down and get the smaller system. I read somewhere that you should always round up, but somewhere else, maybe these foums, it was posted that you should consider whether you plan to make explansions or improvements to your home that would affect the capacity you will need in the near future. Wish I had a better answer for you. BTW, how easy was the HVAC Calc program to use? Thanks.

bm4branes · May 16, 2007

step 1-establish your expectations
step 2-hire a qualified contractor and convey your expectations to him
step 3- make the solution fit the problem, not the other way around.
step 4-let the contractor do what he's getting paid for.

all due repect, why can't the contractor handle the details? wrong contractor or wrong customer?

tigerdunes · May 16, 2007

bordo

I know this is rather late but why do you need the furnace with the radiant? heating system?

Have you thought about dropping the furnace in lieu of a var spd air handler and 3 ton two stg Infinity heat pump? How are your electric rates?

Just an idea.

imo

dash · May 16, 2007

Not sure where you found 36,000 btus total for that equipment match.

Like I stated before"1. You/they need to look at the load calcs.,sensible and latent btus,then be sure the equipment selected covers both.Very important that the equipment rating be adjusted for the number of degrees below standard indoor temp. of 80° F.ACCA's Manual S addresses this."

You are at 95° outdoors ,so no problem,no adjustment needed.

For 75° indoors the deduct is sensible btus is 835 btus ,per degree less then 80° ,per each 1,000 cfms.

So,5X835X1.05= 4383 btus to deduct

I show your equipment at 35555 total and 26150 sensible,then a 3% deduct as the match in the book is for a different coil then yours,which likely won't fit any way.

So,26150 x .97=25365 - 4383= 20982 sensible btus.

Looks like 3 ton is too small,assuming your load calc is correct.

bertrand · May 16, 2007

Establish Expectations....Yep… Over a year ago I got the Infinity system for my 1400 SF ranch + basement north of Chicago.

Did the calcs just like you did. Bid out the system and ended up selecting a Certified Carrier dealer who also did some calcs. Not the low bid – but the most complete bid with calcs.

Something’s that I learned during bidding and install

- Not all factory authorized dealers are a like. I had to change mine during install.

- Load calcs are hard to get from many contractors - and duct calcs even harder.

- My High SEER unit was huge compared to the old one it replaced.

- The Infinity AC unit is not as quiet as the Carrier Brochures or contractors lead you to believe. You can tell it is running for sure – even from inside your home if it is located just a few feet outside a bedroom window. This goes for any AC unit - 69/70 dba is just not quiet. When manufacturers start making AC units with specs like 50 dba and below we can talk about quiet.

- The furnace is quiet at low speed and fire – which is were it runs most of the time.

- Duct sealing methods vary with some contactors from mastic - to nothing.

- An infinity system can do a great job in older duct systems - but if you got real problems with your old distribution you have to look at trying to make those corrections. I added at least two new ducts/supply diffusers to get the home evened out along with some minor damper changes.

-The infinity systems control of humidity (when equipped with humidifier) is wonderful.

- My home has never been more comfortable and controlled .. and that is what I am happy with in the long run.

dash · May 16, 2007

"- My home has never been more comfortable and controlled .. and that is what I am happy with in the long run."

Amen!!

OlManRivah · May 17, 2007

bertrand said:
- My High SEER unit was huge compared to the old one it replaced.

- The Infinity AC unit is not as quiet as the Carrier Brochures or contractors lead you to believe. You can tell it is running for sure – even from inside your home if it is located just a few feet outside a bedroom window. This goes for any AC unit - 69/70 dba is just not quiet. When manufacturers start making AC units with specs like 50 dba and below we can talk about quiet.

Yep, had mine for about 3 weeks now. It's huge. I tell everybody, "I bet my unit can whip your unit!"

And, it is loud. Not objectionable, but not as quiet as they say.

So far so good, but hasn't had the 100* test nor the 20* test.

But, it certainly is convenient. Got her on auto and just let her roll.....

ampulman · May 17, 2007

dash said:
1. You/they need to look at the load calcs.,sensible and latent btus,then be sure the equipment selected covers both.Very important that the equipment rating be adjusted for the number of degrees below standard indoor temp. of 80° F.ACCA's Manual S addresses this..

Is that 835 BTU figure you quoted for a specific coil, or is it applicable to any coil? Is there an adjustment figure for latent heat?

AM

Bordo11 · May 24, 2007

Thanks to all for your ideas.
I was surprised that none of the three dealers were doing a manual J calculation during the HVAC estimation in my house. This is why I have decided to do that by my self and bought the software. I have found a company that do a decent work on the ductwork installation in old houses. They have suggested me to pick up the equipment by my self. It would be the most cost effective way.

Dash, thanks for explanation about how to perform a Manual S.
After adjusting my calculations a sensible heat gain dropped to 22,000 BTUH.
I have seen you mentioned that the half of unused latent btus would be converted to sensible. Would it be right assumption that the 3T unit provided 20982 sensible btus would be enough for my house?
Also you have mentioned:
“then a 3% deduct as the match in the book is for a different coil then yours, which likely won't fit any way.”
Did you mean that CAPMP3617 coil will not fit? I have picked it up from the selector guide. What Carrier coil would you recommend for the horizontal furnace installation in order to get a good performance?

I am still deciding about two speed Infinity 24ANA136.
In my case the noise performance is the key. I have looked at the weighted sound level tables showing the typical octave band spectrum noise levels.
It appears that the Infinity 24ANA136 is more noisy (even on the first stage) than the Performance 24APA336. And 24APA5 appears to most noisy from them.
How is in reality? Can some one to confirm that the two stage 24ANA1 is more noisy. In this case it no make sense to me to by a two stage with a two speed fan unit if the noise is even higher.
I am totally confused.

I would really like to have a two stage two speed fan 24ANA136. It would also allow to match it with the higher output coil and get a few thousand extra BTUs (comparing to 24APA).But it is much larger and noisier. On the other hand 24APA336 is much smaller and quitter but only one stage, and it lacks some performance.
Or I am missing something?
I am stuck. I need finally pick up the system.

Thanks for any help

Bordo11 · May 29, 2007

Dash, why coil CAPMP3617 will not fit with 58MVB060-14 furnace, as you have mentioned?
Can you advise please what would be the right matching coil for the horizontal blow application (installing in a crawl space)?
I would appreciate for your help.

tpa-fl · May 29, 2007

Bordo11 said:
I am still deciding about two speed Infinity 24ANA136.
In my case the noise performance is the key. I have looked at the weighted sound level tables showing the typical octave band spectrum noise levels.
It appears that the Infinity 24ANA136 is more noisy (even on the first stage) than the Performance 24APA336. And 24APA5 appears to most noisy from them. How is in reality? Can some one to confirm that the two stage 24ANA1 is more noisy. In this case it no make sense to me to by a two stage with a two speed fan unit if the noise is even higher.
I am totally confused.
I would really like to have a two stage two speed fan 24ANA136. It would also allow to match it with the higher output coil and get a few thousand extra BTUs (comparing to 24APA).But it is much larger and noisier. On the other hand 24APA336 is much smaller and quitter but only one stage, and it lacks some performance.
Or I am missing something?
I am stuck. I need finally pick up the system.

Thanks for any help

Go for the 2-stage... "Noise" is a VERY subjective thing. Unfortunately, the decibel scale only measure sound pressure and says nothing about the "quality" of the sound. On my 25HNA6 (Infinity heat pump, noisy old-school reciprocating compressor), the loudest sound is the movement of air through the grille, more of a white noise sound, and it's not even THAT loud. I've had conversations with neighbors right in front of it without any trouble. Actually, a neighbor's new Goodman unit 5 doors down from here appears to be louder than my HP *while standing at my HP*. I doubt it is, but the tonal quality of it is vastly different (loud compressor noise). The HP is 6 feet from my bedroom sliding glass door and it's substantially quieter than the beat 7 year old Goodman HP it replaced. I'm an absolute stickler for noise (ask my HVAC contractor, they'll confirm!) and I don't find the noise level objectionable.

Why the ANA1? Even down here in swampy Florida, the payback period isn't high enough to justify the cost difference between the efficiency difference. Also, the ANA7 is quieter:

Code:

      ANA7      ANA1
Low:  69 dB     72dB
High: 70 dB     73dB

Even with the way the rebates are currently structured, there's a good chance the ANA7 will be less expensive unless the distributor has a ton of ANA1 he's trying to unload. Also, it appears these units don't have compressor blankets standard -- add one. They're claiming it can reduce the noise level by up to 3dB.

Also, the ANA1 is a 70% / 100% staging system... the ANA7 is ~58%/100% staging system... I'd rather have the low be low and the high be high. The goal/idea is that the system hangs around in low stage all day long and only uses high for peak periods. Generally, longer runtime = more efficiency.

2-stage rules for comfort AND noise, especially interior noise. My system's run on low 14x more often than high since it was installed. Keep in mind that interior airflow is reduced when the system's running on low, which will further reduce noise levels of the system.

Also, if you're hyper-sensitive about noise, oversize all of your grilles/diffusers and don't use any stamped-metal grilles.

Carrier Infinity – choosing a system, please advise

Bordo11

dash

Bordo11

Bordo11

dash

novakht

Bordo11

dash

Bordo11

diynot

bm4branes

tigerdunes

dash

bertrand

dash

OlManRivah

ampulman

Bordo11

Bordo11

tpa-fl

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