Displayed Temperature Wrong

You absolutely need an separate, fast acting thermometer to set up this thermostat. The suggested cycles per hour are only a starting point. My system, older gas forced air, was supposed to be 5 cph. With the thermostat temperature set at 74, the thermostat called for heat at 71, and when the cycle completed the room temperature was 78. A 7 degree difference. The cycle took about 14 minutes but the temperature on the front of the thermostat never changed from 74.

Way too complicated

Had this installed when I replaced HVAC. Way too complicated for what is a basically a switch on a timer. Has an Emergency Heat setting with no explanation. Also what is Auto setting vs. Heat and Cool settings?

Room temperature off 4 degrees C

Thermostat came installed in a new condo. Thought temperature was reading low, so bought a thermometer. Compared against our bathroom floor thermostat, this is off 4 degrees C. Will be replacing asap with a smart thermostat. Honeywell parts in furnaces that I previously owned were very reliable, so the company should stop selling such low end products that are not always user replaceable.

NIce thermostat

Simple install. Lots of options for all sorts of HVAC systems. Comes with a backer plate if you are replacing an old thermostat that left a large defect in your wall. I have only had it one week, but it seems to be working great. Really good value if you aren't needing to remote control via the internet.

Awesome!

The thermostat arrived a day early, and was just as described. The base plate was included and I was able to install on the wall with all wires attached to it. I watched a you tube video which helped me install it very easily. This thermostat replaced a really old, mercury-bulb type thermostat, but I was glad that I had all the wires in the multicore cable present to connect. I have forced air and gas heat. Everything functioned upon installation. The thermostat itself is used and shows some worn out plastic cover but it doesn't show, and the screen and buttons are all good. The thermostat is programmable. Great seller and great description.

The worst thermostat I ever had

Just got it installed today. Read the directions thoroughly. I'm good at programming thermostats but this one... horrible. You can't program heat and air separately. As you're doing heat, it jumps to cool. You have to use the same turn on time and turn off time. They can't use the term on/off. They have to use wake/sleep. I called my heating/air guy and said get thid thing out of here. They are ordering a different one for me. Horrible directions, can't do different settings for heat/air.

Avoid. Hammer time. Terribly difficult.

Super difficult. I never wanted to take a hammer to a product more in my life. Check out comments in youtube vids and you will never want to buy this. No words to describe how bad it is.

Maybe Honeywell can pay my electric bill?

This thermostat was installed with our new HVAC system last year. With a zero degree non-adjustable deadband my AC is on off every 5 minutes when it’s very hot out. Pretty brutal on the electric bill and not good for my unit either. Looking for a different thermostat with deadband and throw the T4 in the trash.

Not Worth 1 Star

The advanced features are complicated and unnecessary. I've read the manual and set it up properly(I even had a professional do it) but it keeps trying to switch on the heat. It's just not worth it, save your money and find a better thermostat elsewhere.

Scared away

Had a buddy pick this up as a replacement. None of us can figure out how to connect and make it work. Our furnace has three wires , heat only. After reading the, NOT so glowing reviews, I think we will skip this unit and go get a different make. Seems this is a really bad unit and should be pulled from the shelves.

Can’t read anything except current temperature

This thermostat was installed along with a new combo unit (furnace and AC) two days ago. I want my old Honeywell thermostat back! The numbers and all other print (except for current room temperature) are very small and the temperature setting is in the skinniest faintest numbers I’ve ever seen on a digital display. WHY?! There is tons of room to make everything on the display BIGGER and BOLDER. And why offer thermostats that are only available through and need to be installed by an HVAC company? The installer didn’t ask me how I wanted it programmed (5-1-1 or 5-2) or if I wanted Adaptive Intelligent Recovery which I don’t but he set it for “on”. I can reprogram this myself but I have already called my HVAC company and told them to STOP USING THIS THERMOSTAT! My old Honeywell thermostat was working just fine, had large bold numbers for the temperature setting and room temperature, had simple intuitive “up” & “down” arrows to change the temperature instead of buttons that are identical to the other buttons all in a row. NEW DOESN’T MEAN IMPROVED. Don’t let your HVAC installer dump this piece of inferior equipment on you!

Works great with high efficiency gas hot water heat

Using this for 2 years on my main heating zone and like it. I have it set for different temps for weekdays vs weekends (5-2), and a couple degrees cooler at night. It has learned to bring the boiler on about a half hour before returning to my higher morning temp. When we go away for a longer period like a vacation, it's easy to set it to hold a lower permanent temp.

Programming is hidden unless you change functions

Programming is hidden unless you change funtions in ISU. No where does it tell you how to get to ISU, or what each functions is. Support video says all the information is in the user manual, and the user manual has no such information.

Honeywell T4 is just junk!

I used to have an old Honeywell from about 12 years ago and it worked flawlessly.

Looks Good…but that’s about it.

New home with one on each floor. Tried to set them...digits can be changed, but underneath the cover, it decides what it will tell the HVAC to do. Totally unreliable even without programming anything..,just set a temp and hope for the best. Tried to program and it will “save” your settings, but again, under the cover it will decide when to heat and cool and by how much. Totally unreliable.

T4 Proseries Unit

My sister had a new HVAC system installed and it came with the T4 Honeywell Proseries..the thermostat sucks!! The system will turn off and not come back on. The technician has been out twice and can't figure it out. The so called manual isn't any help. Will not recommend this product to anyone.

Zero, I am totally stressed because of this junk

Power black out. Honeywell T4 Thermostat went blank. For three weeks I have been trying to get it to work. It is exactly three years old. It is a nightmare. I am so stressed, and tempted to tear it out of the wall in frustration. One has to be an engineer to figure it out. It is Complicated beyond human comprehension. I am so stressed that my health is affected. I hate this junk, it is total garbage, TOTAL GARBAGE.

Basic cheap unit

Had i known the problems with these units I would have said NO to the installer. My furnace runs way to much. It kicks out at say 21C and within 15 mins its running again,,, I would bet it only drops 1/4 of a dgree and its running. My house R20 insulation and new windows and doors. Evan after changing a 60 year old furnace to an high efficeny one last year ,, I saved a total of $28.00 on my natural gas bill... so NO SAVINGS there and that doesnt include carbon tax crap,,, just usage,, so at that rate I may as well left old unit in and saved the $8,000.00 on the furnace. What a waste of money these so called smart thermostats and furnaces are

Worst thermostat ever

It came with the new furnace and AC and it worked "ok" when the AC was on this summer, but now that we need heat, the stupid thing cycles the heat on for a couple minutes and that's all I get... I need it to go up 3 degrees, but nope... Not even a degree and it turns the furnace off. It still shows that the heat is on, but it's turned the furnace off. Only way I've been able to get to the furnace to come on again is cycle the power to the furnace. I'll be replacing this piece of junk tomorrow with a unit that ACTUALLY works. Hope the kids don't get too cold tonight.

Worst thermostat I have ever had

I cannot stand this thermostat. It worked well for a while, but now, it has a life of its own. It won't hold temps and it won't hold to schedules. I'm constantly having to check the app, which is also terrible, just to make sure the thermostat hasn't set my AC to a ridiculously low temp. We went on vacation last month so I set up a schedule on the app. I check my app one night and what do you know, the thermostat completely disregarded my schedule and had my AC down to a ridiculously low temp, in the middle of the summer, with no one home. So in addition to the frustration of not having a thermostat that works as told, it also loses money, so that's fun.