Wouldn't let me post URL's in the main post, so hopefully the screenshots will post here from the Mitsubishi and Daikin source material. imgur. com/a/uDCrceK

 

3-Tons for 1200 sq ft?

 

Manual J says heating is 3 tons, but current central air is 2.5 ton and we are sticking with 2.5ton due to my preference to not risk oversizing.

 

All heat pumps loose capacity as outdoor ambient falls.

 

Sure, but as the OP says, why does Daikin say it retains 100% capacity but at -4F, but the engineering data shows a loss of ~33% from 47F to 17F? Mitsubishi data shows same BTU/hr output down to 5F, which is consistent with their 100% capacity claim to 5F.

 

The MPG on my car doesn’t match what they claim.

 

Vehicle manufacturer's claiming MPG values meanwhile the real world experience not aligning is not the same thing at all...

The issue here is Daikin is seemingly claiming two very different things that do not align, and I'm trying to understand why. Daikin says 100% capacity down to -4F. 100% capacity is stated to be 34,000 BTU/h. They then say output is 34,000 BTU/h at 47F, but it drops to 22,000 at 17F. And they don't say what it is at -4F. But, because it's claimed to be "100% capacity at -4" I would have assumed it would still be 34,000 BTU/h from -4F to 47F. Therefore, 22,000 at 17F puzzles me. I am trying to understand how both manufacturer claims are true.

On the other hand, Mitsubishi says 100% capacity in the brochure and their engineering data backs this up.

Finally am allowed to post the links: https://www.mitsubishicomfort.com/t...bishiMegaSite/src/img/productPDFs/ME_ M-Series and P-Series Catalog_05-2021.pdf page 158 and https://hvacdirect.com/media/hvac/pdf/Daikin-SkyAir-Engineering-Manual.pdf page 33

 

Let’s get back to 3-Tons for 1300 Sq Ft

 

3 tons and 750 speeds, whats the problem?

 

that can be a separate thread on the forum if you'd like, as that is not the issue here I am trying to address. You're welcome to come over and do the Manual J if you don't believe the two HVAC contractors in my area who both provided the same conclusion.

 

For what it would cost from eastern LI. Not going to happen.
You only have one chance to get it right.

 

I wasn't genuinely suggesting you come to my location to run a manual J when I've had 2 done already And "You only have one chance to get it right." exactly why I'm trying to do my homework to get the right unit for me.

For anyone reading this far, hopefully you can help shed some light on this discrepancy I found in Daikin's data. When I called Daikin the rep was puzzled and was not able to find an answer.

 

The engineering data catalog you linked is for a different Daikin model, not the "Aurora" model the marketing claim you quote is for.

 

I dont know much about the Daikin line anymore but I have been selling Mitsu for some time now. Knowing what I know about Mitsu I would encourage you to stick with them over any other brand. Daikin isn't a bad brand. But nobody compares to the Mitsu support and backend help. Remember, they been here 40 years and have a phenomenal infrastructure. The Hyperheat is a wonderful piece of equipment and the new SM series units have made a huge jump in energy ratings I noticed recently. Also a huge jump in costs too. But that SM model number qualifies for any kind of rebates that might be available. The Mitsu Air handlers are like a piece of art, just a wonderful piece of equipment that feels and is good quality.