I have 24 year old two story home in Sugar Land (SW Houston) with two Trane XR17 units installed 5 years ago and a Nest learning thermostat that is 12 years old.

(The Trane XR17 is a highly efficient, two-stage central air conditioner and heat pump system that delivers up to 18.0 SEER. It is widely praised by HVAC professionals and consumers for balancing premium comfort with reliable energy savings)

Apparently, Trane now makes a proprietary smart thermostat that can target and maintain a set humidity level, which the Nest and other smart thermostats cannot at this point. The Nest can operate the 2 stage units effectively but cannot target humidity levels (unless I had a whole home dehumidifier which my AC guy doesn't like to install because he says they put out too much heat and costly set up).

The new set up would require two thermostats and additional wiring and all in cost is approx. $1600 and has a 10 year warranty. I have a few hygrometers stationed throughout the house and the levels seem to stay at upper 50s, to low 60s but gets better in the afternoon when humidity is down a bit (relatively speaking for Houston).

The AC guy says the new set up could easily target a 55% humidity and be more efficient as well as it would operate a lower level for a longer period of time vs traditional units that switch on and off as needed and not as efficient.

Anyone have any experience with these variable cooling units and thermostats?

Thanks

My two stage system maintained 40-50% in my Hempstead home. That's the entire point of the two stage and any Honeywell EIM stat or system will achieve that. I had Daikin and it was a communicating system with my Honeywell thermostats.

The system ran all day long on low speed and water poured out of the condensate drain 24/7 during summer months.

I never liked Nest. They were never communicating and they had no programmable targets or humidistats. They are user grade equipment. Honeywell EIM is professional grade and requires a pro to install it unless you can read the install manual. You won't find it at Home Depot. You don't have some goofy pretty interface with 4 options. It is an installer menu with endless options for staging, humidity, targets, ranges, etc. Not sure what the current product line is but I've put them in every home I own and they work quite well.

You need a thermostat that can measure humidity and trigger the dehum feature on your ac unit. On most that is just the low speed setting but on mine I can even make the ac unit dial down the low speed even more for max dehumidification. That's where you need to know the equipment and stat or find a pro that knows what he's doing.

Ac guys, like many tradesman, get looped into whatever stuff they are selling and often have no clue about other options around in the industry. Thats why I ended up just installing much of that stuff myself.

I like my neat but only because it is on and old system

Heat and cool only

Similar to Nest, only if you have a whole home dehumidifier and still have to connect wires from units to system.

Per who? Your AC guy?

That's trying to sell you a $1,600 thermostat? Also, why didn't your new unit come with the Trane Comfort system thermostat? I purchased a Trane 6 years ago and it came with it. I got a quote for one in our new house and it also came with it. Kind of shocked they installed new units and left a 7 year old Nest thermostat....

We have Ecobees, granted single speed units. But our Ecobee will run the unit if humidity gets above a target range even if the temp is met. Honeywell should do the same.

ETA: That probably sounded a little harsh. If this is the same AC guy that installed the unit I'd be asking why it didn't come with the unit. That probably wasn't a cheap install. Regardless of his answer, I'd probably be calling for a second opinion. If a $1,600 for the 2 new thermostats is really the only way to get them to run the right speed based on humidity, I'd say it's probably worth it. Not sure I'd be giving the same guy the business, though.

Agree with Trane quality facts posed.

RH% 45 or lower ALWAYS in 1980 house no longer "tight" in humid Aggieland

Trane XV-18 variable stage HP 2021 (but all my old Carrier 1-stage could get close to that since 1980)
4T 1776LivSF 1-story redwood siding R-14/28 walls/attic due to age Continuous ridge & soffit venting Loads of glass R-1 West tree shading glass & outside unit


I might look into an annual tune-up contract (twice/year) that comes with discounts for labor/parts such as these.

We don't need a NEST nor anything else ala cell phones to complicate or lives and steal fun time tinkering with anything beyond golf equipment, guns, ale, BBQ, etc.

htxag09 said:

---

Pretty sure Ecobee can target a desired humidity level....

$1,600 for a new thermostat seems like highway robbery

---

This. Go Ecobee. Btw, a 2 stage system targeting humidity is either (1) overcooling or (2) delaying ramping the furnace/air handler fan. Overcooling is garbage, but ramping is good. You can largely achieve that through an Ecobee and dip switch settings. Ecobee is DIY friendly. $1600 is absurd.

This. Live in Houston. I never hit that rh% in the summer even if my AC runs all day.

Not positive it is worth it. I have a fully variable system and even that can only do so much in an old house when it is really high humidity.

It has to keep the ac going to accomplish anything. My thermostat allows a max degrees below the set point that it can go to try and lower humidity. It will do that and run at a really low speed and it tries hard, but there are days it just can't win the battle.

Here's kind of a good summary.

https://keemeet.com/communicating-vs-non-communicating-hvac/

Done by an HVAC company, so I'm sure some built in bias but still good intel