PG9905 Temp Sensor vs. ADC-S2000 & Garage Freezer Temp Monitoring Application

Hi, I’m hoping to monitor the temperature in a garage freezer, such that I can get a notification from on my phone if the compressor ever fails and the temperature exceeds some programmed threshold. I have an Qolsys IQ 2 Plus panel. It seemed that the PG9905 temperature sensor might be the best choice for this application, especially when used with the optional external temperature probe.

However, I’ve read the PG9905 is limited in that there is no way to receive high/low temperature notifications from when using this device. Is this accurate and current? If this is the case, is there a less-obvious benefit to using this device that I am missing - would there be some local notification at the panel, instead?

Another approach seems to be using a ADC-S2000-T-RA remote temperature sensor for this purpose, but then I’d be forced to place it directly in the freezer (i.e. no external temp probe), which I imagine could exceed recommended environment ratings at worst, and wreak havoc on battery life at best. I haven’t found any recommended operating temperature for these RTSes; does anyone know what they are? Does anyone have experience in using these for freezer temp monitoring applications…?

I have been unable to test with the PG9905 however, you may be able to create a notification based off the thermometer hitting the high or low threshold, this appears to be confirmed by another user here.

The high and low temperature thresholds can be set anywhere in between 180 and -40 degrees in sensor programming so long as the panel is on firmware 2.4.

Another approach seems to be using a ADC-S2000-T-RA remote temperature

You can create a temperature alert using the RTS through The alert can be set for a High of 105° F and a low of -20° F

However, you would not want to mount it in the freezer either as its operating range is 32° to 90°F (0°C to 35°C)

Since it is a Z-Wave device, you would be beholden to having a strong mesh network in the area as well.

Thanks, Tyler! Yes, after reviewing that other thread, and rereading the panel firmware release information, I see that the release 2.4.0 notes state that: “…High/Low threshold reporting for Group 51 now supported by”.

Sounds like this (w/temp probe) would be the better way to go.

Hi, just wondering for someone who has the standard IQ2 panel, are there temperature sensors I can use to monitor my fridge temperature (i,e, if it stops working, or if the door is left open).

I know u can place a contact sensor on it and set up an alert on to send u an alert if it left open but idk if the Iq temp sensor would work to tell if it stopped working or not

Interesting! With the temperature sensor, I might be able to get 2 birds with 1 stone. Say if the door is left open, the temperature should rise (just like if the compressor fails).

U might be able but I just add a contact sensor

when you add the contact sensor (like the a door or window contact), what group do you add it to in sensor type?

For a notification only sensor you would want to use Sensor Group 25 local safety sensor. This can be used for chimes and notifications, but will never generate an alarm.

The PG9905 with a temperature probe would be the best way to monitor for temp inside, described earlier in the thread. As long as you have firmware 2.4 or later you can adjust the temperature threshold to monitor for in sensor programming.

Tanks Jason, but would the PG9905 work for an IQ2 panel with firmware 2.4 or more? If not, what other options are there (besides the fixed IQ temp sensor)

Ah, I see you mean a non-Power G version of the IQ Panel 2, I didn’t catch that sorry. No, you would need the IQ Panel 2+ to use the Power G sensor.

The IQ Temp is not what you would be looking for. I am not aware of another configurable temp sensor with a probe option that would be compatible, but I will check with Qolsys to verify. Will reply here with follow up.

thanks, looks like an upgrade to IQ2+ is inevitable for me. Thankfully the IQ2+ is backwards compatible to the 319.5 MHz line sensors so i don’t loose them all when I do eventually upgrade.

Yes, the standard IQ Panel 2+ with 319.5 radio is compatible with regular 319.5, S-Line, and Power G.

Qolsys confirmed that the solution for this would be the PG9905, but that would require the IQ Panel 2+

I haven’t tried it with an IQ Panel but if you don’t have PowerG, what about using an IQ DW Extended? I think you could use the magnet for sensing whether the door is open and also connect the wired input to something like a GRI T8005 to sense if the temperature gets too high. The only problem I see is that the T8005 is normally open but the wired input is normally closed. You could throw a relay in the middle to invert it. There might even refrigerator temp sensors out there that are normally closed out of the box. Not sure.

Thanks for this info!

Sorry for the late chime in. I think the best solution for you would be the PG9905 with the additional probe. You could drill a hole into the fridge and insert the probe. I tested it with the IQ2+ and you can indeed set you high and low alerts. You can set it to get a notification for a high or low of your set point and it will notify you if the compressor fails. I tested it to trigger an outlet which I wasnt able to do.


Thank you all for your thoughts! I went ahead with the PG9905. However, at this time I have not purchased the temperature probe. I’d definitely like to avoid drilling a hole in the freezer, if possible.

Is there really a compelling need for the external probe for this particular application (freezer temp monitoring)? Placing the PG9905 itself inside the freezer yields a solid signal to the panel, and the indoor operating temperature of the device itself is rated -4 degrees F to 122 degrees F. I would think that the probe would be meant more for outdoor applications, no? I understand that putting it in the freezer may result in diminished battery life, but are there other considerations I’m not thinking of?

The probe is meant to be used in applications like observing the temp of a freezer. Per the instructions, when using the temperature probe, the sensor needs to be mounted outside of the freezer.

Placing the sensor in the freezer is likely going to build up condensation/ice on the sensor which will likely damage the unit in addition to affecting signal strength and battery life.

Instead of drilling, you may be able to place the probe between the freezer door seal and the freezer itself. Depending on the seal this may work as an alternative to drilling into the freezer.