I believe you missed a number - possibly a 4TWR5036N1000?
Or is it a 4TWR5030N1000?
The first one is a 3 ton, while the second one is a 2.5 (2-1/2) ton unit.

TEM6AOB30H21S is a 2.5 (2-1/2) ton AHU, would only match the second one, not the first one.

So you said a 2.5 ton heat pump, if the second one is the correct number, it is a good match - There is nothing wrong with R410a, sooner or later it will be out of production, but there is a drop in available, so not a problem.

Just make sure that the one you are replacing is the same as this one - upsizing or down sizing in most cases is a bad idea.

Eggs

 

You are correct, I missed the 0 in the model number - correct is 4TWR5030N1000. They are also recommending a Trane XL824 Thermostat. I have a zoned system upstairs - this doesn't present any problems, right? As I see it, these are older stock units that have been sitting on a shelf for some time.

 

Ya got to love it when a manufactures gets a product from someone else and puts their name on it. Just more profit - stick to the consumer. Thus why they have been sitting around a while.

NOT a thermostat I would suggest. Although I believe Trane has the best HVAC systems on the market today, that is their goal, Research and development is spent there.

The thermostat I would strongly suggest is the Honeywell T9, which comes with an adapter so older homes with a 4 wire thermostat cable can still use the 4 wires and not run out a new 6 wire cable.
All thermostats that have WiFi require a common power wire to them. Very few homes have enough wire in the wall for this, thus expensive to run a new wire if it were even possible.

The T9 is very impressive - I use these a lot. Being a tech, I do have buildings I monitor and maintain - the app on my phone lets me separate these, so I can see just my home, or select another place. Each can have an endless amount of thermostats in them. The power and creativity Honeywell went though with this is un-real. It will do every thing you can imagine. Geo-fensing if you want. Knows when you are home or away. Goes to set back when gone. Sensors that say wait a minute - we see movement, someone is home, stay at temperature. Can connect several smart phones to it. Has the ability to have several remote sensors. I personally have 3 of them, it averages the temp though out the home, and at night, at night I have it set to control the temperature based on the bedrooms, not the rest of the house. The T10 is one step up can also run your humidifier or dehumidifier, but needs more wires in the cable.

Look into these thermostats, trust me, you will be much happier - you should be able to purchase it yourself, so simple to install, was teaching kids how to do it in ten minutes.
Wiring is broken down as follows - just so you can start to understand it is not hard. Color codes are standard, unless you get an idiot electrician involved (seen that a few times).
White wire - Goes to W - Command for heat
Yellow or Blue wire - Goes to Y - Command for AC
Green wire - Goes to G - turns the fan to on
Red wire - goes to R - this is power, when switched to one of the above, that action takes place
Black or what ever is left - Goes to C - Common to power - this is actually what powers the backside of the thermostat.

IF you have a 4 wire system, the T9 comes with the adapter and clear instructions on how to install - just did one the other day, they work well.
Color coders are close to the same with one exception, there is a K, one of the wires goes there and then we eliminate one of the W,G or Y's - don't recall at the moment, I think we kept the W.

The installer should be able to install it without an extra charge, not that much more work to do.

As for a zone system, with out a lot more details, I could not tell ya - normally a zone system has a zone controller board. Each thermostat for each zone goes to it, then it gets wired to the AHU. So if you have a true 2 or 3 zone system, the T9 handles this well, but you would need one per zone. Same would be for any thermostat.

Hope this helps ya out.

Eggs

 

I guess I'm confused even more now. It's a bit of analysis/paralysis. Is that combo of heat pump and air handler recommended (4TWR5030N1000 with A/H Trane TEM6AOB30H21S) or should I punt and go for a match R454b model?
Other options I'm looking at:
Lennox ML17DP1-030 with A/H CBA27UHE-030 (R410a)
Trane 5TWR5030 with A/H 5TEM4bo3ac31s (R454B)
Trane 5TWR4030 with A/H 5TEM4bo3ac31s (R454B)

Lots of questions, but it's a big investment and I'm not sure what to do.

 

Personally, I would go with what you showed me - good match, good deal.

Now as for R545b - When a product comes out, are you the first to buy it? I am not - I give time for the product to prove its self.
R32 & R454b are new to the market, when I say new, I mean they have not been out for 12 months yet. Right now, none of my suppliers can even get R32 or R545b. A friend of mine works for a Trane Wholesale house and he can not even give me info on those yet. As for the equipment required to even service that equipment is not readily available. R454b is a drop in for R410a, so in the future you are not goi to have an issue.

There are issues with R32 & R454b - they are called an "A2L" meaning (A) non corrosive,2 meaning (slightly explosive), L is slightly higher (explosive).
These require sensors in the home, which in my area are still not available. Things might change in 12 months, but for now, baby steps.
I have been told that in Florida they are installing these, no clue how when I can not even get answers from manufactures. Carrier problem has the most info right now, but thee supplier knows I teach, thus will not give me the time of day. People I know took their training walked away more confused.

Until the market can balance out, get the details figured out, I would stay away from those refrigerants.

As for the Lennox, it is a good unit, but I think Trane is better for many reasons. Their condensers are top of the. line, no one has ever matched them. Plug them up 80%, still work without a problem, it is all in the design. Can not say that with any other brand.

I tell people this all the time on the site - keep simple, lowest SEER, most heat pumps are in the same range when you look at the COP (power in to power out ratio).
Stay away from variable speed condensers, stay away from communicating systems, simple and standard (normal) is best. The easier it is to work on, the less expensive it is to repair. For all we know, R454b may not be on the market very long, no one has any answers right now. If you fins someone with the answers, see if they will sell you a bridge, guessing they will try.

Eggs

 

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UM, I am a professional - 40+ years as a highly skilled service tech. When I say something matches, there is a 0.0001% I am wrong. You would be hard pressed to find a residential service tech with my qualifications. Also a big Trane guy my self, not a dealer per se, but have certifications on many of their specialty equipment also. Trane today is still one of the best out there. Some complain about the new plastic housings on the blower, but it not only is quieter, the efficiency is better. You will find a few other skilled techs answering questions, like Tinkerman - there are a lot of things he know I do not, thus we work as a team here, respect each others opinions. Waldo does a good job at sorting the small stuff out, making my part a lot easier. Team work - always wins - - and by the way, this is not a paid job, we do it for the love of the job.

So I started on this site as I retired about 20 months ago. Needed to stay sharp, started answering questions, helping others. Then one day I was asked to be a moderator, sure - why not. Then a year later I am an ADMIN, still helping out here. This is only a small part of what I do. I also teach the trade to union and non-union students in HVAC/R. Refrigeration is one of my largest specialties as it is by far the hardest to teach and learn. So many factors. Majority of my students are amazed to how far we can take them in a short amount of time. I still get calls from them now and again. Nice seeing that they are doing very well with the education provided. IT is hard work teaching, each and every student is different and come from different worlds. Adjusting to each is always a challenge. Funny part is, I was told not to expect much from them, I looked at that teacher and said, you do not know me very well. Two months later she was curious about me and watch me teach from afar with out our knowledge. The following week she addressed me and said she was impressed on my teaching methods, and how the students responded. That comes from the 40+ years of being a journeyman teaching co-works that are not only apprentices, but highly skilled Journeyman. There is no end to the trade, as it would take many life times to learn it all. Either way, The things I do work on I know better than the back of my hand, then the items I do not know, I either research it out, or have another tech take care of it. Our heads can only hold so much, this is one reason women ask why I can not remember dates very well, tell them the glass gets too full, it over flows and goes away. The trade which makes me money sinks to the bottom, the dates and little stuff is at the top.

Eggs