Question 1

What is the difference between this model and older rth9580wf?

Accepted Answer

I contacted Honeywell about this. This is their response:
"RTH9585 is a newly launched model with a slightly different user interface than RTH9580WF.

Also, RTH9585WF has an additional feature of temporary schedule changes wherein you can adjust the Wake, Leave, Return or Sleep periods based on special requirements such as when you wish to activate return period earlier than usual or when you wish to delay the sleep period."

Question 2

does this thermostat requires "C" wire?

Accepted Answer

In an HVAC system there is a step-down transformer that takes the 240VAC or 120VAC and steps it down to 24VAC. The primary side of the 24VAC is what has always been connected the R terminal of a thermostat. The secondary side of the 24VAC transformer was not. It is this secondary side of the 24VAC that is needed by newer thermostats. In fact the newer thermostats are powered by the 24VAC. That secondary side is what is connected to the C terminal. If your cable has a spare unconnected wire. It could be connected to the secondary of the transformer and then to the C terminal. To see if it is there but but not connected, us a VOM and set for AC Voltage, put one lead on the R terminal, and the second lead to each unconnected wire(s), one at a time. if it shows 24VAC +/- 4VAC, you found the secondary side. All other wires will show OC or open. That secondary side wire is the C wire

Question 3

Does this thermostat have a screen lock to prevent guest from tampering with the settings?

Accepted Answer

Yes, upper and lower limits can be set. Couldn't find anything online to see how to adjust. Chatted with customer service.  The thermostat needs to be unlocked.  Then press settings in the upper right of the main screen, Scroll down to preferences, and choose advanced preferences. Press next until the temperature limits screen.  Adjust.  Limits apply to all three modes unlocked, partially, and fully locked.

Question 4

How does this sense the outside temp and humidity?

Accepted Answer

It displays outside temp and humidity, but these are local weather conditions from the internet, not sensors at your house.

ASIN	B075BF6V58
Backlight	No
Best Sellers Rank	#411,246 in Home Improvement ( See Top 100 in Home Improvement ) #45 in Home Programmable Thermostats
Brand	Honeywell Home
Colour	Grey
Connectivity Protocol	Wi-Fi
Connectivity Technology	Wi-Fi
Control Method	Touch
Control Type	Button Control
Controller Type	Push Button
Country of Origin	China
Customer Reviews	4.4 out of 5 stars 17,510 Reviews
Display Type	color
Finish Types	Matte
Global Trade Identification Number	00085267911313
Item Weight	204 g
Manufacturer Part Number	RTH9585WF1004
Model number	RTH9585WF1004/W
Mounting Type	Wall Mount
Number of Batteries	1 AAA batteries required.
Power Source	Battery Powered
Product Features	Programmable
Product Style	Modern
Shape	Rectangular
Special Feature	Programmable
Temperature Control Type	Heating, Cooling
UPC	085267911313
Unit Count	1.00 Count
Voltage	120 Volts

Honeywell RTH9585WF1004/W Wi-Fi Smart Color Programmable Thermostat, V. 2.0,"C Wire Required

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