Case Study: The value of monitoring a fridge with Home Assistant

Ever talk to someone about home automation and they don’t see a clear way it can be useful to theme? Here’s an example where others in my family completely bought into the tools Home Assistant and some sensors can give you.

Last summer, we had two trips to our family cottage go badly with our youngest having an upset stomach. After the second trip, we threw out all the food we stored between trips (condiments and frozen food) on the off chance something had gone bad even though it wasn’t causing a problem for the rest of us.

I also took apart the fridge to make sure the fans and other bits looked good. They did! Now, this is a fridge from the 1970s, but something great about appliances this old is they really are tanks compared to modern ones. My LG fridge at home is only a few years old and it’s already had its controller board replaced.

I don’t have any photos of the fridge itself, but here’s the freezer unit after I took out the case and some pages from the manual and label. It’s a “Coldspot”, sold via Kenmore / Sears.

I did this work, didn’t see anything obviously wrong, and after all, the fridge was getting cold! But what if the fridge wasn’t working at times even when we didn’t have power outages?

I already had rtl_433 capturing weather station data into Home Assistant. I got an Accurite 986M fridge / freezer thermometer that worked on the same frequency and set up graphs and alerts.

Over a few following trips, things seemed OK. My kid wasn’t sick. The thermometers would show a quick increase in air temperature whenever the fridge was opened, but they recovered within an hour or two. There was one actual power outage where the temps confirmed we should throw out the food. It was pretty need to see the defrost cycle run every 24 hours on the HA graphs.

Last trip, we noticed after loading the fridge and freezer that both were having trouble getting cold again. A day later, we noticed the freezer had been set by someone else to the warmest setting (got to save on the power bill!). Yet, changing that didn’t seem to work either.

Note how the fridge (upper line, I know, entity names need some housekeeping) had a day that never went below 5°C.

By this time, we were about to head home, but we wanted to know if we needed to replace the fridge. Extra smart devices to the rescue!

I try to always keep 1-2 extra Zigbee smart plugs with energy monitoring. They’re just so useful! I was really happy with Sengled plugs, but they became unavailable in Canada so last round I bought the Third Reality plugs. We emptied the fridge and freezer, and I quickly paired a plug with zigbee2mqtt as we packed out.

Looking at the graphs over the next few days, the first thing I noticed was the fridge was never actually turning off.

The kWh graph showed it used 20 kWh in 3 days!

It did get to reasonable temperatures, but was using a huge amount of energy to stay there. Fridges of this era typically used around 2000 kWh a year, but that assumes daily opening and closings that this fridge wouldn’t have seen. 2500 kWh a year with doors closed showed something was wrong.

With this in mind, I turned off the fridge remotely, and it rapidly warmed up. Perhaps the insulation wasn’t doing it’s job anymore.

To finish this up, a few days later about an 8 year old LG top fridge was swapped in, and it got cold within two hours. Look at the incredible difference in slope on the kWh graph:

It’s on track to use less than a fifth of the energy, and we know this fridge is reliable.

Anyways, I hope this post shows one of the values of monitoring appliances with Home Assistant. If anyone else has experiences of detecting appliance issues with thermometers or metering plugs, I’d love to hear them!


After having my fridge fail a couple of summers ago I too monitor fridge & freezer with Govee temp monitors & Sonoff plug with power monitoring.

Good post!

1 Like


This type of post is why I put fridge and freezer thermometers (ZigBee / BLE respectively) in our unit at home.

1 Like

This post is well timed, I’ve noticed that our fridge isn’t getting that cold AND it’s staying on A LOT. I did have a manual read fridge thermometer but that went out recently, can anyone recommend a UK sourced device that I can use with Home Assistant?

About to pull the fridge out and give the heat exchanger a good clean and check, probably kick the wheels while I’m there…

1 Like

Ours was doing that - long run-times and not getting very cold (particularly in the fridge). For us the problem was the defrost circuit - the defrost termination switch (which is meant to end defrost once the coil reaches 10C) tripped too early, so defrosts were never quite long enough - so ice built up over a period of months, depending on humidity levels.


Some cleaning of the heat exchanger and the door seal… AHA! The door seal in one corner is not actually sealing! The rubber/plastic is a bit brittle and will not move back into position to seal against the fridge. Bodged a fix to force the seal and I’ll see how things go overnight. Now trying to find a supplier for a replacement seal, I’d rather that than a new fridge if I could.

If I had a thermometer logging the temperature I might have noticed it sooner? I put the power monitoring plug on only recently and got worried about the power usage. It’s more than our instant water heater in a day!


Did the same using an Aqara multi sensor for temperature and a smart plug for energy (classic old dumb device). Turned out: old fridge was running too hot while at the same time consuming too much energy. Because it is old.

Replaced the fridge, long term power costs are currently monitored and will be compared with the old one in a few months. This way I can pretty accurately estimate (sounds funny cause it’s true haha) the break-even (invest in new fridge vs. reduced power costs).

Two notes:

  • when the old fridge was replaced I discovered the outer rubber seal was damaged in one corner, which is why the fridge was cooling and cooling but exposed a lot of that cool air to the outside (or warm air came in, works both ways :slight_smile: )
  • I noticed it is extremely relevant where the temperature sensor is located. Every fridge has cool and cooler and coolest areas, the last one usually somewhere on the bottom. For reliable (in terms of comparable) data it is important to not change that sensor location after set once. Anyway, it’s still some kind of mystery where the local temperature shown on the fridge‘s own display is measured, as the actual (sensor logged) one is always at least two degrees Celsius above that vendor provided one.
1 Like

Have you had any trouble with dropped readings or the sensor becoming unavailable?

I originally considered doing the same as I already had Zigbee sensors. However, I was worried that the sensors would not send out a strong enough signal to make it through the fridge casing, especially from the freezer where it would be much colder. I ended up going with “made for” refrigerator and freezer sensors since I didn’t have time to cycle through different solutions.

If we could know that typical Aqara or Tuya Zigbee sensors work fine in freezers, I think that would be a good finding for the community.

I have the same exact temperature sensors and I am running rtl_433 and the auto discovery addon. It works great unless I need to replace the batteries. Every new “boot” of the sensors will generate a new ID. For example, right now rtl_433 MQTT is showing the sensor as “devices/Acurite-986/1R/57403/temperature_F” and “devices/Acurite-986/2F/52045/temperature”. If I replace the batteries, the 57403 and 52045 changes to something random.

Does anyone else have this issue and/or know how to fix it?

Here in USA Im using Inkbird bluetooth sensors in my refrigerator/freezers. They take AAA batteries and the signal does make it out of the fridge.


I’m running an ESP8266 in the main fridge compartment and a BLE Xiami thermo in the freezer as a backup for notifications - both get a signal out pretty easily, which was surprising given that all the panels are metal (the BLE signal is on the weak side). YMMV of course, but as long as you’re not hoping to video call over it things seem OK :slight_smile:

Oh, and the CR2032 battery is VERY unhappy - it believes it is dead but it’s just depressed from the cold - has been running for months.

1 Like

Take a look at add device_topic_suffix arg by unverbraucht · Pull Request #144 · pbkhrv/rtl_433-hass-addons · GitHub - it’s not finished or merged yet, but when you see that in a new release it may help with the IDs changing.

Personally, I’ve renamed the home assistant entity IDs, and then I remove the old device and rename the entity IDs when I change batteries on the one device I have this matters on.

No, never. But I have a ZigBee mesh repeater (the SmartPlug :wink: ) pretty close to the fridge, so there’s a strong connection. Material of the fridge is not an issue. I even had the Aqara sensor in the deep freezer for some time, far away from any ZigBee repeater (at that time it was connected to the coordinator, a ConBee II) and it worked totally fine too.

It’s just the temperature which is not perfect for every CR2032 battery. It usually survives something between 5 to 6 months.

I use this one, also in the fridge: Aqara Temperature, Humidity and Pressure Sensor WSDCGQ11LM Zigbee compatibility

1 Like

6 months ago, I had a problem with our Siemens Fridge (in Germany). After pay EUR 100 to roll the truck, the repair man said nothing was wrong with the fridge, but it was frozen at the bottom, not distributing cool air to rest of fridge.

Fix: Turn off fridge for 2-3 days, drain any water. Dry, turn back on.

Additional Key Learning: Don’t trust any temperature displays. Better to buy an extra thermometer (zigbee?) and place inside the fridge.

1 Like

Can you please post a link to the ones you purchased.
Also any yaml code that you use for them.
Thank you.