Honeywell YTHX9421R5127WW Prestige IAQ Redlink Internet Gateway Thermostat Kit

I replaced an older Vision IAQ non-wireless thermostat with this. It took about an hour, including adding the wired return/supply sensors. The old wired unit is very similar to this one, and there wasn't much to move.This has more functionality than most wifi thermostats; it can control heat pumps, multi-source, geothermal, etc. It has four wired sensor inputs, four open or closed dry or powered contacts for operating humidifiers, HRVs, etc. I added two remote wireless indoor sensors and set them up to average with the main unit; took about five minutes. They have a wireless adapter (THM4000R1000) to extend the range, if your EIM is a long way from the thermostat and they can't communicate. This unit can also run zoned systems with additional equipment (TrueZone).Many of these types of thermostats get NWS temperature data from the internet for compressor balance and lockout (heat pumps), but this one can use a wired (or wireless) outdoor sensor for that duty. This is preferable for my application because the nearest NWS reporting weather station is about 20 miles away and is frequently much different than my home, and I don't really wish to depend upon that. If you have no internet and no outside temperature, it determines when to add auxiliary heat by compressor run time compared to meeting demand, which is less than ideal; starting a compressor in cold weather is not good for it.The unit can use the return and supply sensors to measure delta-T across the coils and display (or email) alerts if set points aren't being met in a timely manner while running. It also keeps a log, which is helpful for troubleshooting a failing compressor, etc.This is already making making my house more comfortable just for having more remote indoor sensors; no more cold or hot spots. The remote indoor sensors are easily moved if anything changes, and I can always add more.The Redlink gateway had almost no documentation with it, other than how to take it out of the box, plug it in and admire it. There is a MAC address and MAC CRC on the bottom, which is needed to register it on the website for remote use either with a web browser or a smartphone app. Once the thermostat is powered up and running, the thermostat has an "ADD WIRELESS DEVICES" area in the configuration menu; turn it on, wait for it to start listening, and then push the button on the bottom of the gateway, and it will pair up as long as it's in wifi range. Not difficult, but there are no instructions to give you a hint, as there are with the rest of the devices. Just plugging in the gateway and connecting it to your router will get it recognized on their website, but the thermostat won't show up there until you pair the gateway with it. Then, it shows up almost immediately.Note that this unit is intended for contractor installation, and I'm sure they have more resources and documentation available to them than a retail customer. I'm not entirely sure Honeywell will honor any kind of warrantee since a contractor didn't install it (I'm a retired power plant tech/electrician with decades of experience, but they won't accept that, I'm sure). If you aren't entirely comfortable with, and familiar with heating and cooling systems, you may wish to call in some help; this is a bit more complicated than a basic thermostat.If you have a complicated HVAC system and want wifi and remote functionality, this is a pretty good bet. I've been using Honeywell controls and devices at work and at home for decades. They generally make very good equipment.I have added photos from the iPhone app and of the bottom of the gateway showing the connect button.

The photo of the gateway in the product image is the previous model. Look at the image of the product photo in my review -this is the version of the gateway that I received. First of all, if you just have a simple HVAC setup, this product is NOT for you. A Nest or Ecobee are far better options; I’ve owned all 3 and the phone app for the Nest is the best, Ecobee is second best and the Honeywell Prestige is a distant last place. But that’s not why I bought the Honeywell Prestige. I bought it because it’s the only system that can control the HVAC, fresh air and dehumidifier AND also has remote humidity sensors and wires thermometer probe sensors inside the air handler (temperature differential). This thermostat was recommended to me by the manufacturer or my dehumidifier: UltraAire. While I must admit that the phone app and interface on the thermostat are quite dated, the system is incredibly reliable and feature rich. This system offers a plethora of options in terms of how specific you want to setup your controls. For example, I programmed the system to shut the dehumidifier off when the AC is running. You can also set a timer to require the dehumidifier to wait 5 or more minutes before it turns on after the AC cycle is complete. I also programmed the system to not take temperature differential tests (these tests are to make sure the system is working properly) while the dehumidifier is running. The system also controls my fresh air intake (I use my dehumidifier for fresh air intake) via a Honeywell damper controller. I am not an HVAC professional but I read enough documentation and watched enough YouTube videos to figure it all out on my own. 3 months later and the system is still working perfectly-I couldn’t be happier. Actually… I could be a bit happier if the mobile app was more modern, but it gets the job done. You can set the humidity and the temperature on the mobile app. Every else including the fresh air intake has to be done on the thermostat. Warning: installing this unit is frustrating and not intuitive. But it’s well worth it once it’s all setup.

I replaced my older VisionPro thermostat so that I can have wifi access. This kit had everything I needed including thermostat, EIM, and internet gateway. I asked my HVAC service company several times about adding wifi and they didn't really seem to want to deal with it. Honeywell says ask a professional installer. It wasn't easy to find information, but I decided to take this on as DIY project after reading another product review.My system is a Lennox gas furnace and an air conditioner with heat pump. It was a reasonably easy upgrade since the wiring from the old EIM matched the new module. I was able to use my existing wired outdoor sensor. There were a few install codes that I had to research regarding the heat pump / backup forced gas heat control, but install went fine. The install interface is much easier to program compared to the old thermostat because it is in plain english and has help options.The display looks nice and works well. The wifi access and the my total comfort app allows me to change settings while out of the house or travelling. Happy I did this.

I bought this to replace a Honeywell VisionPRO IAQ. My need was to have wireless remote monitoring and control. The existing system was installed by HVAC contractor on a new home and heating/cooling system. My system has an outdoor heat pump single stage with a two stage air to air, air handler. I'm not a HVAC professional, but I have a background in industrial power plants. The new Honeywell YTHX9421R5127WW Prestige IAQ Redlink was easy to install and setup. The setup is fairly intuitive, but did require me to do some research for certain settings that I did not fully understand. The instructions are pretty vague and probably written for a HVAC professional. But I'm confident that my setup is correct. The display as shown on the picture is much nicer than it looks in the picture. I was pleasantly surprised and think I could not have picked a nicer unit. Also, the temperature sensors included with this kit are for the return and discharge ducts. You can set up limits for minimum and maximum temperature deltas and alerts. This is a useful feature to determine if your system is functioning properly. I was able to reuse the existing outdoor temperature sensor as well. I still have room for one more sensor as well (hard wired), and multiple wireless sensors. The included Redlink Gateway was a breeze to setup and install. I'm using a free app from Honeywell to monitor my thermostat and system. This was easy to setup and use. The Equipment Interface Module hookup was fairly simple and only two wires are connected to the thermostat to power it up. The EIM and thermostat communicate wirelessly to each other and through the Redlink Gateway. I'm not utilizing all the available feature this system has but many of the features. The thermostat also has a USB port to download the settings to a thumbdrive as well as read and load the settings from a thumbdrive. This is handy if you should loose your settings or have to replace the unit.

The control unit i received in this kit simply did not work, thankfully we had a spare and once we swapped it out it was communicating with the thermostat. The unit itself was in mint condition so I’m guessing it was a lemon and why the cost was reduced so much but the description did not mention it was not working.This thermostat gets the job done but if you’ve had a nest or used to their software prepare to be disappointed. The thermostat is a resistive touch screen, think pre iphone technology, the app is ok but definitely not as sleek as Google’s offering.