Was Manual J done to determine the 3 ton load? 3 tons sounds grossly oversized for 1300 sqft.

Manual D determines your duct sizing. Really can't help you there or give you accurate advice as to how large the duct has to be. Could be 20x12, could be something different. Depends on space available too.

Flex will not be the same throughout the home because not all areas require the same airflow.

Mastic is the way to go. Makes a very good seal. Flex should be strapped as well to prevent crimping.

If you question your dealer being able to do things the right way, like size ducts and perform proper install, then you need to find another dealer.

I have some concern about the 3 ton system as well. My current system is a 2.5 ton and it did a good job when it was operating properly. The Evolution / Infinity only comes in full ton sizes. I have been told that because it is a 2 stage it will run in the lower stage most of the time and with the Evolution Controller and variable stage air handler short staging will not be an issue. Do you agree with that? I had a load calculation done and it called for 2.8 tons leaving the existing ductwork and attic insulation as is. When the ducting was changed in the program it called for a 2.5 ton. While changing the ducting and adding additional attic insulation the software called for a 2.1 ton. So i am really right in between which comes back to the 2 stage unit. Please tell me if My thinking is flawed. I really want to get this system right.

You're taking all the right measures to make sure the system is done right, first of all.

The problem with the 286B model--while it is a good unit--is that low stage capacity is really around 82% of full capacity in most sizes/configurations. Your particular matchup is no exception. So in low stage, your capacity is roughly 29,400 btuh, which is 2.45 tons. That means you are oversized under many circumstances in low stage. Where is the comfort and efficiency in that? It will have high stage when you want to recover a temperature setback, but I can't see it using high stage much otherwise--and I don't see it running long cycles in low stage anyway.

It's unfortunate Bryant is stopping the 286A model, which used a compressor capable of a 50/100% capacity split. Then I would have no issues using a 3 ton if you had a 2.5 ton load.

Are there any home improvements you can do to bring your load down to 2 tons and use the 2 ton unit? Bigger is not better, and a properly sized unit will be far more comfortable and efficient.

My opinion. I don't like the idea of putting the 3 ton 286B model in your 1300 sqft house. Others may have other thoughts. If you have to, use a properly sized single stage unit. It will cost less upfront and may do just as good a job when configured right with a humidity-controlling thermostat. I hope what I'm saying makes sense.

I understand exactly what you are saying Ryan. That is the same concern I have. My contractor suggested a 2 ton from the get go. I am the one who is concerned it is too small because my current unit is 2.5 tons. I had another dealer do the load calc. I need to have my guy do the same. My home has new windows and only gets sun from two windows. The rest is shade by porches and trees. I could put more insulation in the attic but I am not so sure that would make a difference in the cooling mode since cold moves down.

needheatpumphelp,

Ryan is steering you right. The best way to protect yourself is to get several estimates, ask for three references, check the BBB for complaints, make sure the contractor is licensed and insured.

Taking on the role of the system designer makes you more liable should there be problems. The contractor can say "Well thats what you wanted". If your contractor does not want to do the calculations before suggesting a system, find someone else who will. Also get everything in writing, if it's not in writing, the contractor is not obligated to provide anything that was verbally told you. Written contacts superceed verbal contracts - I learned that from Judge Judy.

Hope that helps

Dan

I spoke with Dave at Classic and he informed me that the first stage is 67%. I have been unable to find that information in the Bryant specs though. It would mean the first stage would run at 2.1 tons and makes me allot more comfortable than running at 2.45 tons.

67% is the compressor's effective capacity. But it is not the total system capacity. This is coming directly off Dave's website, where he has published Bryant's product data. See the link below, page 19. Your net capacity, due to the larger coil sizes, is much more than 67%. It will be 29,400 btu's, which is as I stated 2.45 tons. Please don't buy the system under the impression that the system will run at 67% capacity. I know York's design allows it to run around 72%, but Carrier/Bryant is really around 82%. Same with Trane and the XL16i. That's why I've never seen a huge benefit with 2-stage systems.

Here is a link that might be useful: Bryant 286B product data - see pg. 19

The Utra tech Copeland scroll compressor unloads at 67% capacity. The scroll compressor is 95% efficient on high speed and 94% on low. This is why the scroll at this time is the number 1 compressor for residential application. when it works it works efficiently.

However there is other factors for your over all application.
coil size of evaporator, fan speed, coil temperature to regulate your TXV metering valve. ect..

Copeland states their 2 speed ultra compressors take 53% more humidity out of the air then their single speed compressors, I will have to find out what this means, is it combined with variable speed or just a constant cfm.

Data on the 286B

2 ton 286B with FE4C-3
23,000 btu high 19,400 btu low

3 ton 286B with FE4C-5
36,000 btu high 29,400 btu low

3 ton 286B with FE4C-3
34,600 btu high 28,600 btu low

what you want in a two speed system is for your system to run at low speed most of the time. It will take less energy and take out humidity.
your 286B is similar to the 226A but with data control so since I'm in Fl and we don't have the 286B yet I will say that it should run around 4.8 to 5.5 amps in low spead around 8.5 to 10.5 amps in high.

You want the high speed for the time of day that it is the most hot and days that it is very hot.

two speed with variable speed air handlers have change the way we think or I think. And it has nothing to do with what the data specs say or what a computer tells me the thing should be.

As we discussed most load calculations unfortunately are used for sales pitching.
It's not the exact, it just gives a frame of reference so a professional can make his decision. No two programs will give you the same btu nor will two people give you the same end btu it's just a frame of reference. Data in is data received and we all perceive data differently.

I've done loads since they came out on DOS back in 1989. It is only a guide for me not an end all.

Let me say, that we can get even more precise, with a home energy audit and HERS rating with a blower door and duct blaster test.
We can also grade your insulation, yes it's just not about R-value there is 3 levels of how the insulation was installed.
It gets so ridiculous that it has become ridiculous.

You may have to look at your home, see how your old system performed. Did it run all the time last summer? We had a hot and rainy summer last season.

All these factors I use when I give a bid to a customer.
I really focus in on the customer gut feeling too and what temperature is your comfort level. Many Manual J are based on 78F temp in side your home. Well what if you like it at 72F and what if it get's 98F and stays there for 2 weeks? Then this should be changed in the manual J for a proper rating.

You know your energy bills, you know that the system before either ran too much or not enough, or it was pretty much out of site out of mind.

The good thing is that over sizing is not like it was 10 yrs ago. There is variable speed air handlers and 2 speed compressors that can regulate humidity and your comfort level and this is what we are trying to accomplish, a comfort level in the most efficient way that doesn't cost a million banana's

If there is a concern, you may want to look at the FE4C-3.
it looses a .5 SEER but has less btu's and it is a slant coil that is much easier to clean.

It is very hard for me to give advice since I have not physically looked at your application, but I do know you have a very good contractor that should take care of your needs.

ryan,
yes you are correct by looking at the specs,
but you should really look at 2 speed compressors systems and not get caught up in paper specs.
They are really worth looking into. specs are specs,
If your line is York I'd really look into the 2 speed systems they have.

But just wait if it is confusing now, which for me it is.
we are actually going to be phasing into a digital Scroll that regulates the compressor 10% to 100% of it's capacity. That's coming soon at the end of the year.

Right now
Nordyne has there 40% to 118% capacity rotary IQ compressor.
which reminds me, I have to take their on line test.

I am real impressed with two speed compressors (not including the XL16i)
when a system runs at less than 6 amps for a 3 ton hp for cooling it gets my attention. Field testing i've done they range from 4.6 to 5.7 amps on low speed ~ Given the load demand and outside temp on low speed.
I have only got those results from a single speed compressor that is water source(heatpump).

"I have some concern about the 3 ton system as well. My current system is a 2.5 ton and it did a good job when it was operating properly. The Evolution / Infinity only comes in full ton sizes. I have been told that because it is a 2 stage it will run in the lower stage most of the time and with the Evolution Controller and variable stage air handler short staging will not be an issue."

You are correct to be concerned. I was 'talked' into replacing my 4 ton unit with another (2-stage), when 3.5 would have done.

I'm still waiting for 2nd stage to cut in. Result: Some areas starved for air (read: not too cool).

V

V,
infinity/evolution
You can turn on the High Cool Latch feature.
When a outside temp gets to a certain degree it will go to high stage.

or you can set your controller to Efficiency mode instead of comfort. This will run the fan at a higher speed.

finally
you can add 4 room sensors and it will take an average temp of those sensors bypassing the sensor in the controller.
If you are having issues I would recommend this for you by placing the room sensors in the troubled area's and one somewhere in your main area for an average temp.

Sounds like you have some duct issues.
is your home single or 2 story?