Carrier vs Am Std Unit Question

[TX_Twister]

OK I am here in Central TX and the time has come to consider replacement of my old (15+ years of good service) Trane 1100's ! I have a 2500 sq Ft house with 2 units. Currently the old Tranes are a 3 Ton up and a 2 Ton Downstairs. Up I have about 1500 ft^2 and down I have about 1000 ft^s (with ten foot ceilings). I am looking at a couple of systems and would like any advice in comparing the two. I have a contractor already picked out so this is based on relative merit of the units. Price is a draw between them as well (no more said to stay in the rules of the board). As I grow older I value quiet and reliability so noise matters inside and out. My understanding is that both units qual for the Fed Rebate and are VS/ Dual stage units. The Carrier ARI below I think is a recipricating Compressor vs Scroll (not sure how much that really matters). The cost delta to me for the recip vs the scroll version was what but these 2 units in the same range. Not sure what type of comp the Am Std has on this one. I do wonder about the additional complexity of the Carrier unit (This Infinity 21 can control humidity vs just temp and has sensors in the outside unit to help it dial in temps and loads). As an engineer by trade I am drawn to the complexity but also have seen cases where it winds up not being a real positive. Simplicity does have its place too !

These 2 units are to replace the upstairs unit that currently has a little coil leak (needs 1 charge per season - so far a very slow leak). I also appreciate any input on replacing the down unit despite the fact that it is not truly broke yet. Part if me says bite the bullet and just go for both. The other part says if it AIN't BROKE ... enough said ...

Thanks in advance !


Unit 1 (Am Std :
ARI : 3303215
Allegiance 16 Communicating
4A7A6036C1
C(B,P)48D44+TDR
ASPEN Coil
*UD060R9V3
Amer Std 17/13
3T
36000 cool BTU's

Carrier Unit :
ARI: 3337950
24ANA736A31
C36H175D45(6,9)
ADP Coil
58CV(A,X)090-16
Carrier 16/13
Infinity 21
3 Ton
34200 cooling BTU

Dave in Austin

[RoBoTeq]

Just curious, why are both systems using aftermarket indoor coils?

I know you can get a better rating (actual performance is not better, just the rating is), but will both Carrier and American Standard stand behind the warranty on the outdoor units when they are attached to an aftermarket indoor coil?

Is American Standard having the same problems with coil leaks that Carrier is? Is that the reason for the aftermarket coils?

[smittyii]

the after market coils are for getting that particular tonnage to qualify for the tax break. both are quiet systems and both will provide good service when installed correctly.

[Edwin73]

My vote goes to the A/S. I have'nt had good luck with Carrier or any Carrier products for that matter.

[TX_Twister]

I have another question - What about Carrier with a recipricating Compressor vs Carrier with the Scroll Compressor ? The Scroll compressor pushes up the SEER to 18 from 16 but at a decent chunk of change in up front cost. I think that the American standard unit is a DUAL scroll compressor arrangement. It seems that the new units are headed to scroll compressors - Is the recip compressor that big of a deal ? The specs show that it is noisier (72 dB vs 70 dB for the scroll unit). Would that be noticable ? or not ?

So far it is one vote for the American Standard unit ...

[smittyii]

both have sound blankets i believe. the scrolls are noisier without the blanket especially on startup, but they quiet down pretty fast if the system is sized right. on higher end systems the noise is negligible.

[praha99]

I`m with Robo why the heck are they both those cheap coils? I know he said "aftermarket" but I call em cheap.:D American Standard has a new High efficiency coil out to match up to the new 20 seer.
I also like the Charge Assist on the Communicating 16 Seer. They are super quiet too.

[beachtech]

neither of those units will work properly without the correct indoor unit.

they are both communicating.

the AM unit comes with a full aluminum coil. that coil will outlast the whole system :)

[TX_Twister]

The contractor I selected has also recommended that we go with a few extra return air vents to keep air flow even when doors are closed. Our house was constructed without return vents in each of the upstairs bedrooms. WE have one 20 x 30 in the hall way upstairs. Current unit is 2.5T and replacements are 3T DS VS units. There is a good bit of pressure when closing doors with the AC on currently. I could see how the return vent would help. I actually had those on a newer home I have lived in recently.
I am thinking the added vents would be a good idea. Any input on this or things to be concerned about ? Does it matter how large these returns are (rec is 14 x 14) ? or where they are located relative to the AC vents ?? any concerns about how these tie back in to the main return ? :)


Thanks to all for all the input and advice ....

[TX_Twister]

We have 4 bedrooms upstairs and I am considering getting a return air vent in each room.

[dash]

Yes, add the returns,have them size the ducts and grilles by Manual D, from www.acca.org

Anything else is just a guess.

[RoBoTeq]

If putting in return vents is accessable to the current ducting system, that is the way to go. However, consideration should be made to the location of the return vents to the location of the supply regesters.

If you have ceiling supply regesters, especially on an upper floor application, then you should have the returns ducted into a wall cavity through the wall plate which would be accessible from the attic. Then, using the wall space as the return chase, have the return grill installed near the bottom of the wall cavity near the floor. You should not use wall cavities that have electrical boxes in them.

If your supply regesters are on the floor or low on the wall, then a ceiling return would be best.

A less expensive alternative, not as good but would greatly help, is to have a pass through return in each of the bedrooms where you would have a high wall grill on one side of a wall between the bedroom and the hall and a low wall grill on the other side of that wall in the same wall cavity. This way, the pressurized air in the bedrooms from the supply regester can "return" to the depressurized hall area (depressurized by the hallway return grill.)

[beenthere]

Is your current return grille, a return air filter grille.

[RoBoTeq]

Is your current return grille, a return air filter grille.

Good question. If so, the transfer grills are the way to go. Transfer grills should be 14X6 opening size. Any larger is just a waste.

[dash]

Best not to use wall cavities,now way to seal them,so no way to tell where you might pull air from.Same for transfer grille ,striight thru the wall sealing them air tight.

Find someone that will use Manual D, to design returns for the rooms,taking into account what you have for a return and making sure it's large enough too.

[Nytefog]

Are you sure the Carrier ANA7 has a recip compressor and not a scroll??

[DGIO-Not]

Are you sure the Carrier ANA7 has a recip compressor and not a scroll??

I think the NA7 was a typo. Carrier hasn't utilized the recip for quite a while inlcuding with Payne (but I am not a Payne expret..my apoligizes in advanced if wrong.) Most manu have made transition, even Trane/Am Stan has made the transition in upper SEER, However, we all remember Snow Ball so I may be wrong here as well.

Although one manufacturer was disparaged over another, it is your installing contractor and their abilities that make the system work as designed. I do have my personal opinoin and what I am comfortable with. However (you knew it was coming) there is one fact I cannot get around..and we spend alot of time this board communicating this fact. A sub par unit when installed correctly will perform great and last way beyond the "serviceable" life. A name branded unit, such as Carrier/Am Stan when installed incorrectly will be your lemon and be nothing but problems and a disposable unit that you will replace well within the 10-12years as per consumer reports (Even as low as 6-7 years) of service if installed incorrectly.

We still service units that are over 40 years old, not becuase we like seeing the low energy efficiency, but because they were installed correctly, serviced competently and the homeowner just decided "I am going to wait till it dies." When the homeonwner is elderly, they really do consider "Savings to Investment" ratio.

[RoBoTeq]

Since HVAC systems are not negative pressure systems but rather rely on the higher pressure in a room to "push" returning air back to the blower, there is absolutely no reason to not use wall cavities for return air and/or for transfer passages. It is done all the time in the best of houses.

[local553]

Best not to use wall cavities,now way to seal them,so no way to tell where you might pull air from.Same for transfer grille ,striight thru the wall sealing them air tight.

Find someone that will use Manual D, to design returns for the rooms,taking into account what you have for a return and making sure it's large enough too.

i dont know how duct work is set up where you are from but here in midwest returns in the walls are very common and work great .

[dash]

Wall returns will pull/move air from the adjacent wall cavityif there's a path,same for floor joists.They have been eliminated by code in Florida for years,due to research by FSEC.

The latest edition of Manual D cautions about this ,as well.


Just open a hole in any return duct,and see the air be pushin in by the surrounding higher pressure!!!


Sure they are used in many areas,just not the best way to go.

[RoBoTeq]

Must be a difference in construction methods or quality in Florida. There are no problems such as this in other parts of the country. No difference between a joist space and a duct that hasn't been sealed at every joint.

Return chases should only be in interior walls, so where would any leakage wind up coming from; another interior space. Just makes no difference.

[dash]

True,no different then an unsealed duct.Point is the ducts should be sealed.

Wall returns can pull air from attic or crawl,particilarly when added to an existing structure.

Check some wall returns with a mirror and a flashlight,you'll see the dust pulled in along the edges of 2X4's.

When we Aeroseal a house with wall retuns it takes extra time to seal these leaks,compared to ducts.

Aeroseal contractors in the north report major air leakage from panned,and walll returns.

[RoBoTeq]

Y'all southerners best leave our Yankee typical construction practices alone, ya hear?

[TX_Twister]

OK - The return vents that I am looking at are 14 x 14's and will be in the ceiling (somewhat access limited with the re-exisiting structure). The supply side vents are on the wall near the top in each room. I am assuming that the returns even in the ceiling would help with the air flow. Ideally I would like them opposite the supplies but for a situation where the AC is the primary use item (Austin Texas gets HOT) I think that pulling the hot air back in from the top would be OK. In the winter this will not be ideal but thankfully winters are short !

The 24ANA1 is the scroll compressor the 24ANA7 is indeed a recip compressor. Check the website - it is crystal clear http://www.residential.carrier.com/products/acheatpumps/ac/infinity.shtml

The unit was installed without the returns (scheduling snafu). I am still contemplating having them put in the returns in the bedrooms to improve airflow with the doors closed. I went with the 24ANA1 scroll compressor. I am not sure what Carrier coil I got on this puppy but I did get the extended 10 year parts / labor just in case. If there is a way to determine the coil type from carrier let me know. I was surprised how small the furnace and coil were on this unit. Thankfully they were not as large as the condensor !

The Carrier 24ANA1 unit is great. I am very happy with the variable speed fan in the bedrooms. The low speed fan and de-humidify / low AC mode is very quite and is almost un-detectable. Outside the condensor is HUGE ! If you are thinking of this unit make sure you have lots of space outside for this. The outside unit is not noisy but not silent. Not sure if the scroll is really any quieter than the recip ? Certainly quieter than the old TRANE XLE 1100 it sits next to (Downstairs unit is still going strong). The scroll SEER and EER where a bit higher on the scroll and I figured to go with the unit that represented the best efficiency and newest tech.

Dave in Austin

[dash]

Return would be best located in the ceiling,close to the same wall the supply is on,keep it 3 feet away from the supply or more,not directly opposite the supply..