Humidty in curing chamber

[David DAngelo]

Hi all,

new to this and hoping for some help. I setup a True bev fridge as a curing fridge - with inkbird humid/temp controllers.

my issue is that I set the temp and everything is in check - 55F and 75% humid. Problem is when the compressor runs, the humidity goes down to 45%, then when it stops, the humidity goes up to 81% before dropping back down to 75%.

Any ideas to prevent this dip/spike when the compressor is running? I think what happens is that when the evap gets cool, the air condenses over it, thus lowering the humidity in the camber, then when the comp stops, the evap warms back up and the condensation on the evap goes back into the air. But why doesn't it go back to 75%, instead spiking to 80?

thanks,
dave

 

[mike243]

cold air develops a vacuum and will pull air in the colder it gets, the moisture that's in it plus the new air and every time the doors opened it will add more,the only way to control is with a evap with defrost cycle to get rid of moisture out of cabinet

 

[David DAngelo]

I live in CO, so the outside air is like 40% humid. This happens when the door is closed and the cabinet is sealed.

 

[daveomak]

The cooling coils condense the moisture on the plates.... the humidifier turns on.... when the compressor turns off, that "frozen" moisture reenters the air... thus the 81% humidity...

Reduce the compressor "ON" time... Have it turn on for "maybe" 5 minutes every hour and see where the temp runs....
ALSO... you need some thermal mass inside the refer cabinet... maybe 4 ... 1 gallon jugs full of water...
AND a small fan to circulate air... I use this 4 CFM fan on a timer...

 

[David DAngelo]

Awesome! Thank you guys for all that - thermal mass for sure.

Here's where I'm at. the Bev fridge originally had the evap fan running all the time - and would just cycle the compressor. I separated the two and had the fan running with just the compressor hooked up to my external temp controller.

The humidity controller would run the humidifier basically when the compressor turned on, so it would cycle through, and the humidity would spike to 84 (from 75).

I sat there and manually turned off the humidifier while the comp cycled and it only went up to like 79% (from 75%)

One idea was to get a time delay relay - so that the humidifier wouldn't run when the compressor was running, and then the time delay would wait 5 minutes after the compressor ran, so the humidity would go back up. I've got this arriving tomorrow, so we'll see how that works.

One thing i did do today was make the evap fan cycle on/off with the compressor - now the humidity drops and it needs the humidifier to get back up to 75%. . . . . I do have a small 23 cfm computer fan that runs constantly down below to help distribute air internally.

Sooooo, here's what I'm thinking. I want to run the evap fan for a couple minutes after the compressor finishes to get the humidity back up quickly . . . can accomplish this with the time delay relay.

I will also use another relay timer to delay the humidifier from kicking in until after the evap fan runs. as it is now it's fine, but the compressor running does drop the humidity significantly. once i get some water jugs to up the thermal mass in there I suspect this will help with less compressor cycles. right now i have the compressor turn on when the temp goes 3 degrees higher than 55 - the compressor cycle gets it down to like 53.

thanks guys!