Contact Sensor for Refrigerator or Freezer Door?


This weekend, my wife or I - probably my wife :slight_smile: - did not shut our secondary freezer door all the way. Needless to say, some of the items in it thawed out pretty good.

I was looking for a way to install a contact sensor or something like that to create rule to prevent this from happening again. However, with the rubber gasket around the door, the gap is too large for a contact sensor to work.

Are there any other alternatives or has someone come up with a clever way to do what I want to do?



Try the bottom of the door (if it's an upright), some of mine have the vent close enough to the door itself, before I was using like 10 layers of double sided tape for the magnet to be close enough until I looked there.

Also I'm using the Fibaro FGK-101's with the DS18B20 temp sensor inside of each fridge/freezer to monitor the temp (doesn't look pretty but I "should" never have your event happen)


I'll have to look at the bottom. Didn't think about that. Also didn't think about a temp sensor inside of the freezer. Didn't think the electronics would like the coldness. I'll look into that as well....

Off topic, did you guys get flooded up there? Oklahoma right? I'm in Chickasha and we fared pretty well. But I thought I saw one of your posts where you live in NW Oklahoma.


That's what I was referring to with doesn't look pretty. The contact sensor is on the outside of the fridges/freezers and the corded DS18B820 temp sensor goes inside with the door closing on it. Ya before this I tried the contact sensors inside the fridges/freezers, it will destroy the batteries doing that.

Yes, I live in the NE corner, been flooded for almost a month, every time others go down they close off more gates making it rise back up here.


I work for Union Pacific Railroad and I was noticing yesterday all the rivers out that I have never seen out. All of the farmland and houses affected....Just sad.

I went to school at NEO in Miami. Spent a lot of time at the chat piles in Picher area.... Ahhh, those were the days :slight_smile:


Yep that's my neck of the woods graduated from Miami, live on Grand Lake now...


Been there a few times..... So, did you ever go looking for the spook lights?


Yep a time or two


You might also try the new Samsung contact sensor. It has to be very far from the magnet to trip. Not ideal for most contact sensor applications, but it might suit this particular use case very well.

If I recall correctly, it also measures temp, so the cold air around it might also work as a secondary trigger for a notification.


I think I have one of the V4 versions I think. That the one you are referring to? I'll give it a try.


They actually make wide gap contact sensors like these:

The problem you are going to have with any contact sensor is that to detect when the door is just barely open is very difficult. You want to make sure that the sensor is as close to the opening side of the door as possible to give it the greatest distance of travel when it is open. What might actually be better is a contact sensor that works off of a plunger, like this one:

Now, how you would rig that up to a fridge? I have no idea. Just throwin it out there as an alternative you might be able to use.


Maybe a light-based sensor to detect the fridge light?


You could create a small bridge using something thin like a piece of cardboard, aluminum plate, stiff plastic, etc. and 3M command stick it on top of the fridge and door. Then stick the sensor to the end of that to bridge the gasket gap and the magnet on the door. I have Xiaomi contact sensors and they are pretty small and light so this would work with those. Not sure about other brands.


Aren't there magnets within the rubber door seal on fridges/freezers ??
If so they might trip a door/window type sensor.

I'd start by adjusting the freezers feet just a touch so it reclines ever so slightly backwards and let gravity help keep the door closed :slight_smile:


That would probably work in normal circumstances, but what caused my issue was a package of meat slid down and stuck out ever so slightly causing the door to not close fully. Didn't notice it until it was too late.


ahhh, got yah.
I think @bizapp is on the right track but you could also enhance it by putting a power meter on the freezer, keeping track of power consumption etc etc
oh the joy of having another HA project to direct funds too.


I would highly advise against this, UNLESS you really have $$$$.......This rabbit hole led me to replace both fridges and both freezers, because I realize Damn that fridge uses double the electricity of a new one, then the cost/benefit analysis comes in to the electricity savings vs the return on investment for a new fridge.....I've currently done the same with TV's and my last replacement TV will be coming this month, but my electric bill is much cheaper......grrrr


@spalexander68 I saw this and thought it might work. It has a trip temp of 41 deg. If the probe is close to the door on the inside it should detect the rise in temp above 41. A little high of a trip temp but might have saved most things. The cord thickness shouldn't break the seal, it looks pretty thin.


This one. Is that version 4?


That;s the one I have. Saw someone refer to it as V4, but honestly I don't know.