Instruction: Analyze a question and its supporting document. Predicting answerability based on the information provided in the document. Output yes if the document contains relevant information to answer the question, otherwise output no.

Input:
Question: Will this thermostat operate in a dual  fuel mode that turns off the compressor when the aux gas heat is turned on?
Document: Unfortunately, if you are using this thermostat with a 2H/1C system, with fossil fuel back up heat and heat pump, it turns on heat pump AND fossil fuel back simultaneously until the thermostat figures warm air is coming out of your vents. Big problem is this will ruin your outside compressor due to high pressure in the system from heating the evaporator coil. big no no. I'm returning it and getting a Pro1IAQ T955WH instead.
This is an excellent thermostat but it took some research beyond included instructions to get it wired correctly. I have Lennox heat pump with auxiliary gas furnace, so getting the changeover valve and auxiliary fuel wires on correct terminal took some extra research. There are numerous customizable settings making it work in any situation.
(NOT good!) Now we should have a fully automated system that turns over by itself.I really like that this item can be wired to an optional outside sensor; we've been using a digital remote thermometer to decide when to switch off the heat pump, kind of a hassle. (Especially when we've completely turned off the heat pump overnight and have to walk to the opposite end of the house to read the outdoor temp first.)
The thermostat itself is ok. The only real complaints that I have about the actual thermostat is that the stuff displayed on the screen is small and the backlight turns off too quickly (and the one I received is defective)...I bought this particular thermostat because I can set the fan to "Circ" mode which will turn the fan on for several minutes every hour to recirculate the air in the house. I like this feature since it helps regulate the temperature better in my two story house.
The concept of this 7-day programmable Honeywell thermostat is great; however, even after having it professionally installed at considerable cost, it still is not working as advertised. When the furnace is supposed to back off from the heat mode during the day or at night, the system kicks into air-conditioning and is blowing cool air.
This thermostat is easy to program and edit the settings  for  wake, leave, return, and  sleep for heat or cool. I use it for a gas furnace and electric AC. I was unsure of which wires go on the proper terminals. I called Honeywell  twice. They are not willing to give tech support for wiring this thermostat because it is a "professional model and I would need to call a contractor".
I recently bought this product because I got tired of setting my manual thermostat everyday. I've had it for a few days and so far it's been easy to use and program, the touchscreen is the icing on the cake.Things you should know before installing:1) Look up wiring diagrams for your current thermostat to figure out which wires do what. This will help you with wiring your honeywell..2) Know if your heating system is multi-stage (with Emergency or Aux heat, etc).
Checked the terminals and found the O/B terminal (for the changeover valve) to still be energized. So I did a system reset and reprogrammed it. Tried it again and found that the heat would not come on, it would be cooling instead. Checked the thermostat terminals again and found that the O/B terminal would not energize in the heating mode (used a simple ohm meter to check which terminals were active).
I purchased the Honeywell TH8320 to replace an existing analog thermostat. I needed the following:1) Programmable settings2) Keypad Lockout3) Auto Changeover4) Filter reminder (this is a nice thing to have not required)I removed the old thermostat and installed the new one in about 15 minutes. I had one wiring error (labels were different on the old thermostat). When I first tried to power on the Heat Pump it went into heat mode.
I have had this thermostat on a high-end Lennox 2-speed heat pump for the past 8 years and have had to replace it 3 times due to it failing to keep proper temperature and fan/compressor speeds. After a couple of years the thermometer becomes very inaccurate. My third one just now says it's 58 degrees F in the house when it is 78 and the fan is cranking at max speed, so looks like I'll be replacing this 3rd thermostat with another brand this time.
Answer: yes