Enhance my Raspberry-Pi controlled cheese cave

[Mykeul]

Hello

I am making cheese as hobby and I do not have an under-earth cave to refine them.

Living in France, I built a cheese cave with an old wine cellar and an humidifier, in a country that has a Relative Hygrometry(%HR) of 30% in summer and 99+% in winter.
Year 1 tests with only temperature control + humidifier leaded to mainly cheese covered with blue moisture as soon as I close the door of the cheese cave, whereas all was clean white before.
I plan to do better for Year 2.

My cheeses need 15°C + 85-90%HR and I think that it need "new air flow" to help good bacteria continue developing.

The new build is :
- Raspberry pi zero
- 2 humidity & temperature senrors (BME280 via I2C) for internal and external temperatures (DHT11/22 are not stable enough at high %HR)
- 4 relays (GPIO) to manage :
  * The humidifier (terrarium humidifier)
  * The dehumidifier (normal room dehumidifier)
  * The fan for new air intake (40mm)
  * The fan so that the air inside the cave is not static (40mm)
Note : the wine cellar manages to keep 15°C well, so my problem is mainly humidity + new air.
Note2 : FYI Intake pipe to enter the cheese cave is 30mm diameter, outtake pipes to go out of the cheese cave are 2 x 10mm.

I have everything together, connected and working, and my biggest question is about the "algorithm" (i.e. if humidity < 80% then start humidifier etc...) to maintain the right atmosphere in the cave.

It is sure that all has to be done in "slow times", to avoid continuously humidificate then dehumidificate etc... so I start the humidifier for 20 seconds, then wait 5 minutes to recheck %HR, even more for the dehumidifier in winter.

I wrote a normal algorithm that manages the humidity, it maintains it basically correct ... except when in winter air intake is 99+%HR + some new cheeses are inside, raising the humidity by themselves. If I run the dehumidifier too much, it makes the cheeses as hard as rock because it sucks humidity out of it. I do not know handle to handle this.

However, I have exactly no idea on how to manage the air intake, too much will be as if cheeses were outside of the cave, too little makes the cheeses' bacteria develop very bad and become blue

Poor Diagram :


Do anyone of you have any idea on how to handle this air intake ?

Secondary questions : any idea for humidity in winter ? any idea how to place the internal fan to have the air non-static, like in 'no frost' fridge ? (I did not find how to)

Thanks for your help.

Mykeul

[paulabob]

Wondering if your rh sensor's placement compared to fan, humidifier, and dehumidifier.  I think that can have some impact.

My own rh sensor is extremely slow to update (like, it can take 30 minutes).  I would make sure yours is closer to realtime before automating.

I have my temp controls automated (using a wifi sensor, automated plug, and ifttt recipe), and basically run two minutes on, then a check every 10 minutes to determine if out of range.  I don't have the right setup for humidity.

[Mykeul]

Hello

Yes I understand for the placement, I think of putting the fan at the bottom, blowing to the top and the sensor in the middle, protected  in a little box with holes.

The BME280 is not real time but I did some tests and it changes value when approaching mist within seconds, so I am not worried about this.

Thanks for the suggestion, what about the "change of air" or "new air intake" ? If I do not do that, then the cave fills up with CO2 & Ammonia (from what I read) and then bacteria is not developing correctly.
As of now here is my algorithm :
- For Humidifier, if %HR < 82 then run it for 20 secs, then block any other action for 5 minutes
- For Dehumifier, if %HR > 88 then run it for 30 minutes, then force stop it for 1 hour
- Humidifier & Dehumifier cannot run at the same time, and no more than 1 cycle Humidifier then Dehumifier, or reverse, otherwise force stop for 1 hour
- Internal fan is running 1 minutes every 10 minutes
- External fan (air intake) is running 15 minutes each 12 hours, blocking any other action during those 15 minutes.

[paulabob]

From what I understand, just opening your fridge twice a day is enough fresh air intake.  However, not sure that factors in humidifying.  Hope someone has an answer for you, I would be interested.

[SDmilkmaid]

For your winter air intake, can you set up some way to "pre-dehumidify" the air before it goes into the cave?
Ie. Set up a wind tunnel, of sorts, that houses your dehumidifier, and attach it to your air intake. You'll have to take into account that the RH% will rise in the cave compared to room temp air. Anyway, crazy idea.
Rachel

[Mykeul]

Thanks to you two for the help.

Opening the door once a day to change cheeses face is not sufficient, at least from what I saw.
The pre-intake box can be a good idea, but it has to be thought about because the dehumidifier needs at least 30 minutes to be efficient.

I continue to work on the project, I did some adaptations and I am now quite pleased with the result, I will make cheese to verify.

[zymurgist]

Mykeul --

Any updates on how your cheese cave is doing? I'm trying to do something very similar here in the USA. Would love to hear about what you've learned.

Merci beacoup,
Matt