Easily Refillable Charcoal Filter For Liebherr Wine Fridges

Do you (or anyone you know) own any of the following models of Liebherr wine fridge?

WKt 6451,
WKb 4212,
WKes 4552,
WKr 4211,
WTes 5872,
WTes 5972,
WKgb 4113,
WKb 4612,
WKb 4112,
WKb 4611,
WKb 1712,
WKEes 553

Do you (or your soon-to-be friend) want to save a LOT money on those replacement charcoal filters while reducing waste?

Want to be able to EASILY refill the filter over and over with new charcoal?

Me too! That's why I made this :-)

A LITTLE BACK STORY:

I use my WKb4612 wine fridge as an affinage (ageing) space for my home made cheeses. It has a charcoal filter that allows the fridge to "breathe" without allowing corks/labels (or cheese in my case) to take on weird smells, and get rid of certain fermentation-related gases. In short, it's handy for wine mavens, but it's even MORE handy for cheese makers. The smells with most aged cheeses are stronger, and parmesan can take years to age properly.... that's a long time to accumulate (and generate) smells that might be... "less than ideal". :~)

However, I "bought my filters in bulk" as a package deal with my shiny new fridge back in 2019... However, at the time of writing in early 2025... that stash ran out. So I went to order some more and...

Wait what? $90+ Australian dollars, delivered... for ONE?! (That's about $57 USD at the time of writing)

So I cracked my old one open to see what I was really buying. It was quite difficult to open, and I actually lost the lid in a high speed blur across the room... but all that was in the filter... were some loose 3mm pellets of activated charcoal, and a couple of sheets of synthetic-yet-breathable fabric to stop any charcoal from slipping through the holes on either end.

I weighed out the pellets, and it was about 20g....

Let me make this clear... at the official filter's price... that's $4.50 Australian (about $3 USD) per GRAM of charcoal. A gram is about 3% of an ounce... so in total a full filter of this size holds about 60% of an ounce...

No matter what units you use... that's not much. Similarly, it was wrapped in a plastic shell that only involves 32g of filament to print (about an ounce, even including organic supports). This thing can be made dirt-cheaply, and my intent was to design it so you could open the little threaded lid on it, line the holed ends with two small circles of breathable synthetic fabric, then just pour some new charcoal in. Sit another piece of fabric on top of the charcoal, and screw the lid on.

(Pro Tip: You can even use the circles of fabric from the original filter)

To contrast this price. I can buy 1 Kg of 3mm wide activated charcoal pellets online for $39.95 Australian delivered... that's roughly 50 refills... which at $90 each... would cost $4500 (that's more than my fridge costs!). That's about 50 years worth of filters for the wine aficionados... since Liebherr recommends replacing it every year or so.

However, that's only 25 years for cheese makers.. since a 6 monthly replacement schedule has proven (in my experience) to be better. That might not be necessary for the fresher cheese makers, putting their Fetta/Quark/Chabichou/Lactic acid cheese skills to work... That said, it becomes particularly important for cheese makers who EVER make anything in the more aromatic/washed rind cheese categories or any makers who tinker with the stronger gas producing cultures.

So for a total of about $45 Australian ($30 USD or so) and some time prototyping... here we are. Long-term freedom from 99% of the ridiculous price of proprietary charcoal filters! Just print, fill and install. To replace the used charcoal, simply open, refill, and reinstall. Rinse, lather, and repeat every 6-12 months (metaphorically speaking).. or whenever you notice any smells getting out of hand. I don't want to encourage anyone to get into the habit of "sniff, rinse, repeat".. because that could be misconstrued ;-D

FILAMENTS, FUNCTIONALITY, AND FOOD SAFETY:

I chose PETG for the close similarity it has to PET plastics found in many food containers like soft drink bottles. It doesn't swell in humidity nearly as much as some of the other filament types, so that should maintain functionality over time. Also, the higher humidity of a wine fridge means PLA's "relatively organic" composition, and the various, really hygroscopic plastics aren't ideal in this situation.

If you're particularly worried that PETG filament isn't food safe... please note that this should never make contact with any of the food/drink in the fridge. It's a glorified air filter.

Yes, it's theoretically possible that the gaps/texture of FDM/FFF printer jobs can harbour microbes.. but so does the air it filters, and all the "nooks and crannies" that are common to every fridge I've ever seen. If you're hugely worried about it, complete the print, do any post-printing "clean up" (removing support material, and removing any extra bits) then wash it in warm soapy water, and let it sit to dry completely in open air. Once all that is done, fill with charcoal and install.

I encourage everyone who makes this DIY filter, to inspect/wash the filter each time they refill it... and with the vastly reduced cost, and wildly improved ease of maintenance, both of the major reasons for filter replacement procrastination have been largely removed. That's got to be healthier than an official filter that hasn't been replaced in several years. :-)

As always, do your research, come to your own conclusions, and most importantly, take responsibility for your own decisions and actions. If you use recycled mystery gruel filaments that glow in the dark, have non-food safe additions, or react poorly to humidity... it's not going to be my design that causes issues. Use this model intelligently and you'll be fine.

All the best!
Ham.