Honeywell 5821

Wireless Temperature Sensor and Water Sensor

Honeywell 5821 wireless temperature sensor and water sensor exte
  • Honeywell 5821 wireless temperature sensor and water sensor exte
  • Honeywell 5821 wireless temperature sensor and water sensor inte

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Honeywell 5821 is a wireless temperature and water sensor for those who want to monitor freezing and flooding. In stock and ready to ship!
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The Honeywell 5821 is a wireless temperature sensor and water sensor. The 5821 wireless transmitter can either be used as a standalone temperature sensor or it can be used in combination with the T280R temperature sensor probe or a water/flood probe. The 470PB or FP280 can be hardwired to the 5821 and configured for flood detection. The 5821 ships with a 2.2M ohm resistor to be strapped in parallel with a 470PB. On the other hand, the FP280 comes with a 16.5 foot cable that already has the resistor wired into the circuit. Honeywell created the FP280 to make it easier for end users or DIYers to setup flood detection. The 5821's dip switch settings along with the programmed loop number of its wireless zone will determine which type of protection the 5821 wireless transmitter will be providing.

Without any probe the internal temperature sensor of the wireless Honeywell 5821 can be used to monitor the protected room's temperature. As a standalone temperature sensor, the 5821 can monitor for cold, warm or hot temperatures.

Program your 5821 wireless sensor as loop 1 with both dip switches off for cold temperature monitoring and the sensor will fault when the temperature drops below 45° F for more than (10) minutes.

Program the 5821 as loop 2 with both dip switches off for hot temperature monitoring and the transmitter will fault when the temperature rises above 95° F for greater than (10) minutes.

Program the Honeywell 5821 as loop 2 with SW1 dip switch on and SW2 dip switch off for warm temperature monitoring and the temperature sensor will fault when the temperature rises above 75° F for more than 10 minutes.

If you wire the T280R temperature probe to your 5821 wireless temperature sensor, you can use it for remote freezer temperature monitoring or refrigerator temperature monitoring.

Program the Honeywell 5821 as loop 2 with dip switch SW1 off and SW2 dip switch on for freezer temperature monitoring. When the T280R temperature probe detects temperatures above 10° F for more than (30) minutes, The 5821 will trigger an alarm.

Program the 5821 sensor as loop 2 with both dip switches on for refrigerator temperature monitoring. When the T280R temperature sensor detects temperatures above 42° for more than (30) minutes, the 5821 will trigger an alarm.

If you wire the 470PB water probe to your 5821 wireless water sensor, you can use it for water leak protection.

Program the Honeywell 5821 as loop 3 with dip switch SW1 off and SW2 dip switch on for flood monitoring. When the 470PB water probe detects water for more than (3) minutes, The 5821 will trigger an alarm. The Honeywell 5821 is an extremely versatile wireless environmental sensor. Not only can it do local cold, warm or hot temperature sensing or remote freezer, refrigerator or flood sensing, it can even do local cold temperature monitoring simultaneously with local warm or hot temperature monitoring or local cold simultaneously with a remote temperature or water probe.

Program the 5821 wireless sensor as (2) separate wireless zones with cold as loop 1 and the other type of protection as loop 2. The dip switches should be set to match the other type of protection for proper detection. The 5821 will trigger an alarm when either event occurs.


Yes it would if you were able to get a Z-wave water valve programmed in the system and then set up a scene for the particular events.
Hi Sterling.... if this is paired with a Lyric Controller which does play nice with Z-Wave, should it be possible for an alarm raised by the 5821 to tell the Lyric Controller to activate a ZWave WaterCop? i.e. can this + Lyric = water shut off in the event of freezing &/or leaks?
There is not really a perfect all in one device that does all that. I wish there was! However there are some options. The 5821 with FP280 will cover low temp alarms and flood and I highly recommend this for starters. It covers the really important stuff. The tricky part is live remote readings. That can only be accomplished with a thermostat. If you want to setup a WIFI thermostat and just keep it in the off state you could certainly try that. There are some fairly affordable WIFI thermostats out there. If you want to tie it into Total Connect 2.0 it will need to be a Honeywell ZWSTAT (Z-Wave) or a TC comfort WIFI thermostat. This is not the intended use for these products. Lastly if you want to setup custom thresholds you may want to check out the EA200: This product will offer live local reading but not remotely. When a threshold is reached this device will throw a relay output. I recommend connecting the output to a 5816:
I'm looking to tie in a sensor for my crawlspace for low temp and possibly water, we have an L7000 system - what can I use to get readings of temp throughout the day as well as alarm when it reaches thresholds?
The Lyric Round or the Honeywell ZWSTAT. is there any sensor that can just tell me the temperature without any range or min or max?
The 5821 will alert you through your lynx if the temperature hits any of the above mentioned thresholds.
Will this give me the temperature through my lynx touch 5210?
We're not sure exactly why Honeywell has the built-in delay but suspect it's to avoid false alarms. To avoid the delay, you could use a wired flood sensor (such as the 470-12 - ) and wire it to a wireless transmitter (you could use a SiXCT as it has internal screw terminals for a NC device).
As the other commenters mentioned, the 3 minute delay gives me pause with this. Any insight why Honeywell have this delay on this specific sensor? Any objective reason waiting 3 minutes would be preferred (maybe false positive prevention?). Their other water sensors (like the wired one) don't seem to have this delay. Any official or semi official methods/techniques/devices to implement wireless water monitoring but without this 3 minute delay?
Yes, if your VISTA-21iP system has a wireless receiver, you can use a 5821 sensor with your system. I don't see that we have any account associated with your email so if you are signed up with us, please email from the email you have on your account so that we can help and if you are with another company, I would suggest you check out our no-contract monitoring plans at and consider switching to us as we provide free technical support and are experts on the VISTA-21iP system.
Can this be intergrated with vista 21p panel? I already have total connect, would like to get the communication thru that
No, unfortunately, that timing can't be adjusted.
Sterling, is there any way to make the 5821/FP280 trigger faster than 3 minutes? A broken main water line can do some significant damage in 3 minutes. Thanks
No, the monthly fee only covers the service provided with that plan. You would need to order the equipment separately.
So is the Lyric panel included with the $10 monthly fee?
The only equipment cost is the cost of the equipment you would need to support the service you are looking for. The Lyric panel with the 5821 would be all you need, but you may want to add the LT-CABLE ( ).
This looks interesting, Sterling. Is there an equipment costs to set up the self bronze self basic interactive plan?
The Lyric system ( ) would work with that sensor and has a built-in WIFI communicator. With our Self Bronze plan at the bottom of our sign up page ( ), you'd have access to Total Connect 2.0 so you could arm/disarm the system remotely from a computer or mobile device and receive text/email alerts from the system on any alarm activity.
No,I don't. What do you recommend?
Do you have an alarm system? If so, which one. The sensor doesn't work as a standalone sensor.
If I use the 5821 as a temperature sensor for my house while I'm away, can it be programmed to text or email me via my WiFi router if the room temperature drops below 45 F?
We agree Milton but unfortunately, we don't have any updated information on when/if the integration for that water/freeze device will come to the Lyric panel.
Sterling, any word on if the Lyric Wi-Fi Water Leak and Freeze Detector can be integrated into a Lyric security system? Honeywell does themselves a disservice by putting out products with the Lyric brand name that aren't ready to work together.
I appreciate the the info. Thanks
No, it will only send the alert if the low temperature threshold is hit. It won't provide you live temperature readings.
With the 5821 setup to monitor a freezer, is there anyway to check the temperature from the lynx7000 control panel?
The Tuxedo Touch is a Z-Wave controller but it's not an RF wireless receiver. Do you know if your system has a wireless receiver installed now? If you have any wireless sensors or key fobs now, you would know you have a receiver. If you don't have a receiver, you can easily add one by getting a 5881 Series model (like the 5881ENH - ) or an RF keypad with an integrated receiver (like the 6160RF - ).
I have a Tuxedo Touch and want to rig up a temperature sensor in my freezer. I just lost about $650 in meat because of a B.S. GFI Outlet. It's not the Wifi Version of the Tuxedo.. I'm willing to up grade my keypad to a Wifi Tuxedo. But my question is if I get this 5821 will this work for what I'm looking to do, also do you know if I will need the Wifi Version of Tuxedo.. I'm so pissed off because when I built my house 2 years ago I told my Alarm guy I wanted the best and latest equipment. Now he's out of business and every time I want to do something my stuff is not compatible or I need to upgrade something..
No, this is a Honeywell RF sensor for wireless Honeywell alarm systems.
Is this z wave compatible?
It seems that for now you just buy them directly from the site you linked to above and that yes, eventually all Lyric devices will be integrated but for now, you'd use those as standalone devices with the Lyric app. If you wanted to tie in monitored water detectors for the Lyric system, you'd need to use the 5821 with a 470PB probe.
Thanks, Sterling! I would prefer to buy them from you. The customer support on Honeywell chat simply told me that I don't need the thermostat and that you just add the device in the Lyric app. He sent me the instructions: It seems to me that it has a lot of potential. I hope they add support to the Lyric controller I just purchased from you so everything can be integrated. All in due time, I suppose.
We did confirm you can use the leak detectors as standalone detectors with the Lyric app. I'm still finding out if we can get them and if so, when we'll have them listed on the site.
Well, we clearly don't know much about these Lyric WIFI devices and our rep was the one that said you need the thermostat to use them so let me see if we can find out some more information and let you know. Do you have what Honeywell told you exactly?
Honeywell is telling me that it doesn't need the thermostat, just the Lyric app. Trying to decide between the Lyric detector and this one (5821). If you have any insight or advice that might make one better than the other, I would love anything you can share. I am hoping you will carry these leak detectors in the future.
Thank you. I will reach out to Honeywell. That information is certainly not on their website (and a major bummer, if true), but I do already see someone complaining that the app isn't picking up the sensor.
We're not sure if and when we'd carry them but yes, I think you'd need a Lyric thermostat (at least for now) to use those devices.
Thanks for the response. Seems like it would be a no brainer for everything Lyric to work together. Does that mean you need to have a Lyric thermostat for the leak detectors to notify you, etc? I thought you just needed the Lyric app. Will you be carrying these? I like the cord vs the prongs on 5821. Seems like it has more flexibility and easier install.
We've been told that device will integrate with the Lyric thermostat first as an "awareness" device and eventually SHOULD be integrated into the Lyric security system as well but we don't have an ETA or more information on how that integration will work.
Will you be carrying the new Lyric Wi-Fi Water Leak and Freeze Detector? And will that be compatible with the new Lyric controller that I just ordered? Thanks, Kerry
If you have Total Connect you can setup a general monitor zone to only send text/email alerts during specific armed states and schedules. This would prevent the need to bypass the zone during the work hours. It will still alert the keypad when it's opened but it will not require a double disarm to clear it out like a trouble would. Instead after the door is closed it simply restores.
No, you can't program an RF device to only be active during certain hours. However, if you choose zone type 05 Day/Night, the sensors will cause a trouble sound when the system is disarmed and a full alarm when the system is armed. You could train the employees to bypass those zones in the morning after disarming to avoid the trouble during the day and the employees would just have to remember to disarm before arming to un-bypass the zones so that they will be active when the system is armed at night.
Is there a way to program the 5821 (with the T280R) to only set the lynx touch 5210 off during certain hours? Customers leave the Freezer & Refrigerator open for a couple of hours during normal business hours, 8:30am - 4:30 pm. They activate the system when the last employee leaves and they want these 2 sensors to only trip while the alarm is active. I currently have the 2 5821's as type 8's. On the lynx panel there is another option for a zone type besides 8, it's a type 12=monitor. Thanks in advance!
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