C7089R1013 Wireless Outdoor Sensor

Just moved into a new house with Honeywell thermostats and nice A/C systems. These are the first A/C systems I've owned that have 'fresh air' vents versus always recycling indoor air. They're electronically controlled by the thermostat, but I found with the vents open on certain days, the humidity indoors became oppressive (>70%) - adding this outdoor sensor allows me to lockout the vents when outdoor humidity is above a certain level (configured in installer options). Now I don't have to manually switch between external vents and recirculating air. I can just leave the vents on 'auto'. It can also be used to lockout vents when the temperature outside is above or below a certain configurable range. Adding this sensor to both A/C thermostats was a piece of cake (press a button with the thermostat in the 'add a device' screen) and I love the added benefit of being able to see the outdoor temperature and humidity on the thermostats. My thermostats are RedLink style 8321s. I believe this works with any of the RedLink system thermostats. There's quite a distance between my upstairs thermostat and this sensor out on the patio but it seems to have no problems at all. You do not need the RedLink wireless gateway thingamajig for this, it links directly to the RedLink thermostats themselves. Love it! Now I get to enjoy outdoor fresh air in both winter and summer without adding humidity into the mix, and without sucking in 100 degree air (or sub-zero air) in extreme temperatures and overworking the system. Edit: I should note, in case anyone else bangs their head with this one... I struggled getting the vents to open at all when I'd set the high humidity lockout. I was convinced this thing did NOT work properly... Until I realized that on my thermostat, the high humidity lockout setting is set by, and expressed as dew point (degrees) - NOT relative humidity which the thermostat shows. Took me a while to figure that out. I felt so dumb!!!

OEM Replacement. Easy to connect. Zero issues.

This is a replacement unit for my HVAC with gas furnace system. Previous unit quit after 9 years. I didn’t pay attention to “outdoor sensor error” until the recent Jan 2026 snow storm in Washington DC. This bitter cold weeks really put a strain on the gas furnace. Suddenly the furnace locked itself out and temperature inside the house fell to 58 deg F. Apparently the furnace controller needs the outside temperature value from this sensor otherwise the controller gets confused and furnace shuts down. I’m guessing the system uses the outside temperature value to optimize level-1 and level-2 heating. If this temperature value. Installation was super easy. First put the thermostat into “add a wireless device”. The press connect button on the sensor. In 1-2 seconds Thermostat shows a message that new sensor has been added. You may have to use “installer code” on thermostat before you can see the add device menu under wireless devices. After that put the back panel on, and place the sensor outside. It may take upto 30 minutes for the sensor to show the actual outdoor temperature.

Easy setup . Works very well. Sensor is not waterproof. Reequires a cover if exposed to elements.

This worked out good with our geothermal system and Honeywell thermostat; looked up instructions with Google AI; and it was easy to install.

The sensor connected easily to my thermostat. It provides outdoor temp and humidity. The accuracy appears very good since it matches the temperature readings of my previous outdoor sensor. The humidity level gives me an idea of weather fronts as they near. I now find myself referring to my thermostat more for outside temperature since I am more accustomed to the feel and settings of the indoors without looking.

Expensive but required Nice product

Update: I have solved my low battery alarm problem on this sensor (despite fresh batteries being put in it hrs before). I did it by buying a 3VDC power supply and used some slide on electrical connectors from the local hardware store to wire it up on the battery terminals. Some very minor surgery to the case to run the wire thru, made watertight with a dab of caulk. Here’s a link to what I used https://a.co/d/00ezMhM3 but any 3VDC supply (same as two AA batteries) will do. It puts out a solid 3.5VDC and now a couple days later no low battery alarm. The check the sensor uses for battery low must be flawed in some way. Yeah this “solution” requires a small purchase and perhaps some wiring work if you don’t have a convenient outlet to plug the supply into but the fact I’ll never see another low battery alarm makes it worth it. ———— Totally useless sensor that tells you it’s low on batteries far more often than the outdoor temp and humidity it’s supposed to report. You’d think something this simple would be braindead easy to design correctly for battery use. It has no DC plug on it so AA alkaline batteries are your only option. Put absolutely fresh batteries in it and in a couple hours it will report low batteries on all your thermostats. Pop a battery out for a few seconds and put it back in and magically the error clears—— for another couple hours and then back on the red light comes on the thermostats. Yeah, you can tell it to wait a week before warning you again but it will be back and in the meantime sometimes it sends the right temperature value and humidity, but most of the time sends 128 for the temperature and the humidity value. Not super useful when it’s definitely not 128° outside. No matter how many times I change the batteries, no matter what battery brand or any other magic incantations I can think of will make it stop doing this. I called Honeywell support, and the only suggestion they had was to do a factory reset on the unit, but even they didn’t sound like they believed that it would work. This thing has been doing this since the day I received it from Amazon so I’m pretty dubious that that’s going to fix it. Given it’s the dead of winter I don’t want to go down into my crawlspace to rebind the sensor to my zoning panel that I have installed after doing the factory reset on the sensor. Maybe in the warmer months I’ll give it a shot, but I can’t imagine why a factory reset would cause it to stop reporting false low battery signals. Fortunately, I was planning on getting a weather station anyway which should give me a lot more information than just what the sensor happens to report, but of course that won’t be tied into my HVAC system so I lose a little bit there, assuming it actually uses that information to adjust the furnace behavior. Honestly, I think I had one of these units previous to this particular unit and it had exactly the same behavior. I should’ve returned this one when I saw it doing the same thing but it’s in a house that I don’t use all year round. My advice is to avoid the sensor at all costs. There are unpowered hardwired sensors that you can tie into Honeywell panels that are probably more reliable and are not driven by batteries. I’m just amazed that a company the size of Honeywell would put out something so badly designed that it can’t go two hours without claiming the batteries are low. I don’t actually believe that they’re low because when you’re pop them out and then put them back in again it can go for quite a while (at least a couple hours) before signaling it again as low battery. Either that or it’s got some sort of problem that just sucks the life out of batteries, far faster than it’s supposed to, but I have no idea what that would be. It just hangs on the wall outside in its bracket and hasn’t been touched since it was originally installed (except for untold numbers of useless battery changes) so nothing should be broken in it. And it’s covered by an eave so it doesn’t get a lot of weather directly on it. And it IS for OUTDOOR USE so a little robustness seems fair to expect. You won’t get it either this junk. If at all possible, just never buy this thing unless you wanna fight with low battery warnings forever. And the worst part is every thermostat has to be reset individually if you want to turn off the alarm for some period of time. If the sensor reports itself is OK then all the thermostats clear the error.. But if you just want to turn off the red light alarm for a few days, you have to go to each Honeywell thermostat individually to do it every time it reports low batteries. Very annoying. You’d think since they’re all on redlink networking, they could all be reset once one of them is but I think my toaster is smarter than this thing. Buyer beware. Terrible value, can’t go a few hours without reporting low batteries and incomplete weather info when it does with no real fix. If another company offered a zoning panel I could swap in for the Honeywell one I have, I’d toss the whole system just from the irritation this has caused me. Wake up Honeywell!!!!! No wonder other companies with better tech are eating your lunch.

Works exactly as it should. Paired with my heat pump right away.

Non è compatibile con evohome

Fast delivery and the product was exactly what I needed. Works well will order from this supplier again. Thank you.

Worked

I bought this sensor to help my thermostat decide what source of heat to use (electricity vs gas). This is controlled depending on what the temperature is outside. Previously it would just hang for 30minutes not heating as it could not figure out what source to use. I hoped that buying this sensor would help it figure out. And it did - my thermostat does not get "stuck" anymore. This sensor works well, provides humidity info and was easy to setup from the wireless section of my compatible thermostat.