Thanks dadoes for the information.

I am interested to understand what "intelligence" this thermostat (Pro T715) uses, but it's really not clear from any of the product literature:

https://pro1iaq.com/images/700Manuals/PM-715-IM-Installation-Manual-Alitho.pdf

Is the idea that the 2 stage system will always start out with the low heating setting and only bump up to the high heating if certain criteria (time or heating rate) are met?

Every 2-stage thermostat uses a proprietary algorithm to control the heating and cooling stages. The manufacturers rarely publicly document how it works. The only feature I see which may make use of a built in intelligent algorithm is the Pro Recovery feature. The thermostat will start the recovery period during a setback early so that it reaches the desired temperature at the beginning of the new period. I personally don't like that feature have turned it off in my thermostats.

The 2-stage thermostat should always start in the low stage, and then transition to the high stage if needed. Most of the time high stage is not needed when maintaining the temperature set point within one degree. However coming out of set back period, the thermostat makes the decision (some intelligence) based on room temperature and cycle duration when to switch to the high stage. Some thermostats will switch from the high stage to the low stage to finish the heating cycle. This is something that can't be done if the furnace control board is selecting the heating stages.

I had a problem with opposite behavior on heating setback recovery. Heat pumps are almost always 2-stage systems, even if 1-speed, by way of having the compressor as the 1st stage and the back-up/emergency electric resistance (or gas furnace) as the 2nd stage. A two-speed heat pump with back-up/emergency can be considered 3-stage.

Mine is 1-speed. I always did a daytime setback during the heating season (or setup for cooling) when I was working days and into the evening on a 2nd job. My thermostat has smart recovery which has it raise the temperature setpoint slowly starting early (much as 2 hrs) of the target time to avoid running the resistance heat, as would happen if the room temp is 62°F and the setpoint is 70°F (more than 2°F difference). Can't do that with a 1-stage thermostat on a 2-stage system (whether heat pump or not) that doesn't have direct control of the 2nd stage. I'd once in a while get home early and recovery was still in progress. It would turn on the resistance heat (as auxiliary) within a few mins of the target time if the target temp hadn't been reached, even if it was only 1°F short, and the blast of extra heat sometimes caused the room temp to overshoot the mark. Running on the heat pump for a little longer (even if 30 mins) would reach the setpoint and is more efficient and avoid overshooting the mark. I had an outdoor temp sensor added that allows locking-out the resistance heat unless the outdoor temp is lower than a specific (adjustable) temperature, which solved that problem.

"A two-speed heat pump with back-up/emergency can be considered 3-stage."

Huh? Not my Hybrid! (Oil backup.)

Google on 3-stage heat pump and see if you can find any source on the face of the earth that agrees with the above post.

lol

PS There are 3-stage heat pumps - typically used in either very hot regions or in very cold regions.

In the early days (1970s, 1980s), Honeywell's heatpump thermostats utilized true "intelligent recovery" from a setback to avoid bringing on the backup resistance strips. It would increase temperature setpoint gradually so that the 2-3 degree backup heat threshold was not activated. Today, all "intelligent recovery" thermostats simply switch the system on earlier so that the setpoint temperature will be achieved at the allotted time, backup heat and all.

My Carrier thermostat is not "1970s, 1980s" - it is about nine years old. It has an option which I do use to "increase temperature setpoint gradually so that the 2-3 degree backup heat threshold was not activated."

"Stax: "A two-speed heat pump with back-up/emergency can be considered 3-stage."

Huh? Not my Hybrid! (Oil backup.)

Google on 3-stage heat pump and see if you can find any source on the face of the earth that agrees with the above post.

lol"

Stax, my parents' 2-speed Lennox heat pump with resistance elements for emergency/auxiliary that can run on low speed, high speed, and engage the elements if necessary is not to be considered a 3-stage system for heating? OK. Good to know.

Unfortunate that the proprietary algorithm makes it so that you can't really understand what is going on.

It looks like there are two adjustable settings that might be useful.

One of them is "Staging Delay: This feature allows a delay to occur when a second stage is needed. This allows the previous stage extra time to satisfy setpoint." It can be set to OFF, 5, 10, 15, 30, 45, 60 or 90 minutes. Default is OFF. Can someone explain what situation that would apply to?

The other one is "Heating Swing", or "cycle rate" which can be set from 0.2 to 2 degrees. That one seems straightforward and the default is 0.4. Sound OK?

Thanks again.

The staging delay is an extra time delay when transitioning from the low to high stage. You could set a delay if you thought the thermostat was switching to the high stage too soon. Unfortunately there is no explanation as what the algorithm is for switching with no delay. You can leave it off and observe what happens.

A swing of 0.4 seem is too small in my opinion. A swing of one degree is comfortable and will cut down the number of heating cycles. Try the default and make it longer if you observe the furnace running on short cycles.