How to Convert a Refrigerator for Curing Meat or Aging Cheese

WARNING: Working with electricity is dangerous. This article will teach you several ways to convert a refrigerator into a chamber for curing meat or for aging cheese.  (The same principles can be used to convert a refrigerator into a lagering chamber for making homebrew lager beer, or converting a chest freezer into a kegerator.)  If you choose the route that requires wiring, I cannot be held responsible for any damage to life or property should your wiring fail.  If in doubt, consult an electrician, and always obey local, state, and federal electrical codes when modifying the electrical connection for appliances.

Folks with a basement or cellar anywhere in the US (or most temperate climates) generally have the proper temperature and humidity range to cure meat simply by hanging properly salted meat in that basement or cellar.  (Though insects, mice, and wild molds can be a problem.)  The finest meats in the world are cured in centuries-old basements in Europe.  But for those of us without basements or cellars, curing our own meat requires a curing chamber that provides the ideal temperature and humidity range.

It’s fairly simple to convert an old refrigerator into such a chamber.  I got an old fridge on Craigslist for $50, but you can often find them in the free section if you’ll be patient and quick to respond once they are listed.  (If you transport a fridge on its side, rather than upright, you need to leave the fridge sitting upright, unplugged, for a couple of days, to let the coolant settle properly.)

The first object is to rig a rack system near the top of the fridge chamber, on which the meat will hang.  If you ever plan on curing whole hams, this rack may need to support fairly heavy weights (25-30 pounds per ham for a large one.)  If you’re just curing sausages, it may not need to be as strong.  If the fridge has wire racks, you may be able to just move the racks to the top of the fridge and hang the meat directly from the racks.  My fridge came with glass shelves, so I removed all the shelves.  I made my rack system out of aluminum from Home Depot.  I bought square tubes which anchor the racks on each end, and used an angle grinder to cut slots in the square tube so I can customize the distance between the racks:

I used a fast-setting epoxy to glue the square tubes to the walls of the fridge.  (Make sure they are level and even with each other!)  Then I just slid the bars into the slots, and placed some S-hooks over the bars to hang the meat.  This type of rack is sturdy enough to cure full-sized hams.

Wood may be easier to work with, but the conditions inside the curing chamber will be damp (around 65% humidity) which provides a perfect place for mold to grow, so I encourage you to avoid wood, if possible.  Get creative!

Once you have your fridge and rack system set up, you need 5 electronic components to convert the fridge into a curing chamber:

  • An external temperature controller/thermostat
  • An external humidity controller
  • A cool-mist/ultrasonic humidifier
  • A thermo-hygrometer (weather station)
  • A fan

The first two items are available on the internet in a wide range of prices, depending on how convenient you want the conversion to be.  The simplest units are plug-and-play.  You plug the controllers into any outlet.  You plug the fridge into the temperature controller and you plug the humidifier into the humidity controller.  You set the proper temperature and humidity ranges, you place the sensor probes into the fridge chamber, and you’re good to go.  Unfortunately, these units are the most expensive.  The plug-and-play temperature controllers range between $50 and $80, like this one on Amazon.  The humidity controllers range between  $50 and $100, like this one or this one.  If you’re not accustomed to electrical work, I strongly encourage you to spend the extra money and get one of these.

For those of you who are handy, there are some cheaper units now available that were designed for controlling temp and humidity in computer server racks, but they are bare-bones units and you’ll have to provide power (via a cord, or wiring them to an outlet), and make your own connections to the fridge and humidifier (either by direct wiring or hard-wire, or by wiring the controllers to outlets.)  The STC-1000 unit for controlling temperature costs about $25.  (Be cautious if you find it cheaper.  Cheaper units may ship from China and take weeks, and be certain you order the proper voltage for your country…in the US this is 110 volts.)  The WH8040 unit for controlling humidity costs around $35.  (Similar warnings for this unit, too.)

I’m going to explain how to hard-wire your fridge and humidifier directly to these units, because there are other articles out there on how to wire outlets to the units, and then plug in your fridge and humidifier.  That’s extra cost, to me, and requires that I construct a housing to hold the units and the outlets.  And I’m looking for the quickest route to efficiency.  Please note that local electrical codes may not like you to have exposed wiring connections.

Let’s start with the STC-1000 to control the temperature of the fridge:

The unit comes with wiring instructions translated from Chinese, and they’re completely useless.  So I’ve made a wiring diagram:

Hard wire the STC-1000 to a fridge

You will need to buy or re-purpose a power cord to power the unit.  The cord needs to be able to handle enough current to power the fridge, so don’t use a lamp cord!  If you use a grounded power cord, you can connect the fridge’s green grounding wire to the green wire of the power cord.  (If you use a 2-wire power cord, you will need to connect the green wire inside the fridge’s cord to the grounding screw on an outlet, or follow the alternate grounding procedure later in this post.)  Using a grounded power cord is preferable.  You will need to cut the plug off the refrigerator’s power cord and strip off the insulation from the hot, neutral, and ground wires.

Some basic electrical knowledge here for those of you who are unfamiliar.  A typical power cord contains a hot wire that carries the current to the device…a neutral wire that returns the current to the outlet, thus completing the circuit…and a ground wire that carries away dangerous electricity if there is a wiring failure inside the device, so that you don’t get shocked when you touch it.

The hot wire is always black.  The neutral wire is usually white…but if there’s no white wire, the neutral wire will be indicated by writing, markings, or ribbing along the cord’s insulation, so look or feel closely to determine which wire is the neutral wire.  The ground wire is either bare copper or green.

So the hot wire from your power cord needs to be spliced to two other short bits of black wire (called “pigtails”) that run to slots 1 and 7 on the STC-1000 unit.  Tape these wires together with electrical tape, and connect them securely with a properly-sized wire nut.  The neutral wire from your power cord needs to be spliced to a pigtail that runs to slot 2, and to the neutral wire on the fridge’s power cord.  The hot wire on the fridge power cord needs to run to slot 8 on the unit.  (The neutral wire on the fridge power cord has already been connected to the neutral wire from the main power cord, along with a pigtail to slot 2.)

When you get done, it’ll look kinda like this:

(You shouldn’t need a heater unit unless your curing fridge sits outside in a very cold climate, but if you do, a heating pad will generally work nicely.  To add a heater to the system, run a pigtail from the black power cord bundle to slot 5.  Run the heater’s hot wire to slot 6.  Connect the heater’s neutral wire to the neutral bundle.) 

The fridge MUST be grounded, or you risk electrocuting yourself when you touch the fridge if the wiring inside the fridge fails.  The grounding wire from the fridge can connect directly to the green or bare copper wire inside the power cord, if it’s a 3-prong cord.  If you’ve used a 2 prong power cord, like I did, you need to connect the fridge’s ground wire to the grounding screw inside a nearby electrical outlet, or you can take a regular 3-prong plug, remove the hot and neutral prongs, leaving just the grounding prong, and connect the ground wire to that prong:

Here I've removed the first prong from the plug.

After removing the other prong, I attach the ground wire from the fridge to the grounding screw.

I replaced the back of the plug and now I have a ground wire that plugs into an outlet, but draws no power, it simply grounds the fridge.

Now you need to plug in the power cord to an outlet.  (I bought a special extension cord that has 4 outlets on the end that will sit next to the fridge.  4 items will need to be plugged into the outlet.  You can also use a regular extension cord and a power strip.)  The STC-1000 unit will power up, and now you need to set it.

The following paragraph details instructions for setting the STC-1000, you can skip this unless you are actively setting the device right now:  Press and hold the S key for 3 seconds to enter the setting mode.  The first item that displays is F1, which is the temperature setting.  The unit is in Celsius, so you’ll have to do a quick conversion.  I keep my curing chamber in the low 60s Fahrenheit, so 18C is the corresponding setting.  To set the temp, press and hold the S key while pressing the up or down arrow until you reach the temperature that you want your curing chamber to remain.  Then press the power button once quickly to save the setting.  (The setting will remain even if your power goes out…it only resets to the default setting if you manually reset the device.)  The other settings don’t need to be modified unless you have problems later.  (F2 is the “Difference value” which tells the fridge when to turn on after the temperature rises a specific number of degrees above your setting.  The default setting is half a degree Celsius, which is fine as it is.  F3 is the “Compressor delay time” which gives the fridge’s compressor a result, because you don’t want it cycling on and off every 30 seconds.  The default setting is 3 minutes, which is fine.  F4 is the “Temperature calibration value” which is used if you discover your device isn’t accurate and you need to adjust it.  To switch between these values in the setting mode, press the S key multiple times until you arrive at the feature you need to change.  If, at any time during the setting process, you don’t press a key for 10 seconds, the device forgets what you’ve done and returns to its operation mode.  Don’t forget to press the power button once quickly to save your settings.)

Make sure to attach the temperature probe to slots 3 and 4 on the unit.  Then run the sensor probe into your fridge and make sure it’s not touching the walls, the racks, or the meat.  Now the STC-1000 unit will keep your fridge in the low 60s…the perfect temp for curing meat.

Now we need to address humidity.  Normal refrigerators run very dry, so you’ll need to add moisture to the chamber to keep it in the low 60% range.  We do this with a cool-mist humidifier, also called an ultrasonic humidifier.  (DON’T use a conventional vaporizer, which uses warm heat to evaporate the water.  This will raise the temp inside the chamber each time the unit comes on.)  Get yourself the largest-capacity humidifier you can afford, so you don’t have to refill the unit every few days.  The unit I’m using holds about 1 gallon of water.  It cost me $30 on Amazon and was fairly well reviewed.  (There is also a pig-shaped humidifier on Amazon, which is supremely appropriate, but the reviews aren’t as good.)

Place the humidifier in the bottom of the fridge and run the wire out the side of the door.  Cut the plug off the end of your humidifier and strip the insulation off the cords.  (Humidifiers don’t usually have a ground wire, just a hot and a neutral.)

Now we get out our WH8040 humidity controller:

We wire the humidifier to the unit using the following diagram:

The hot wire from the power cord connects to two pigtails, which are connected to slots 2 and 3 on the WH8040.  The neutral wire from the power cord connects to a pigtail to slot 4, as well as the neutral wire from the humidifier’s power cord.  And the hot wire from the humidifier connects to slot 1.  The WH8040 has 2 probes that it uses to calculate humidity…a temp probe which connects to slots 8 and 9, and a vapor probe that connects to slots 5, 6, and 7.  Run the probes into the refrigerator’s chamber, and like the temp probe, they should hang freely in the area where the meat does.

When you get done wiring it, the unit will look sorta like this:

The following paragraph details instructions for setting the WH8040, you can skip this unless you are actively setting the device right now:  Press and hold the SET key for 3 seconds to enter the setting mode.  The first value is HC, which tells the unit whether to dehumidify, or humidify.  Press the SET key again, and use the up or down arrows to set this value to H (humidify).  Then press the SET key again to save the value and return to SET mode.  Press the UP key to move to the next value, D, which is “Hysteresis.”  Leave this at its default setting.  Press the UP key again to move to the next value, LS, which is the lowest humidity range you want to keep.  Press the SET button and adjust this setting to 55%, or whatever the lowest humidity is acceptable for you.  Then press the SET button again.  Use the UP arrow to move to the next value, HS, which is the maximum humidity.  Click SET and use the arrows to set this limit to 65%. The remaining settings can be left at their defaults unless you need to modify them later.  CA is humidity calibration…if your unit isn’t measuring the humidity correctly, you can override the settings by plus or minus 5%.  PT is the delay time between turning your humidifier on and off, and the default is set at 1 minute.  Press the RST key to leave the set mode.

Now you can mount your WH8040 to the side of your fridge with double sided tape or velcro.

Again, if all that wiring sounds too complex for you, you can simply buy a plug-and-play temp controller and humidity controller, you’re just gonna spend an extra $75-$100.  Do that, and your system will be set up in 15 minutes.

Now it’s time to place the fan in the bottom of the fridge next to your humidifier.  I got a small metal desk fan on Amazon for $13 that was well reviewed.  The air inside the curing chamber needs to circulate constantly to help dry the meat, so just run this cord out the back of the door and plug it into your power supply.

The final step is to install your thermo-hygrometer, which keeps track of the temp and humidity inside the chamber, so you know if your controllers are working properly.  I got mine on Amazon for $18.  It has a wireless remote unit that I velcroed to the inside of the fridge.  It is battery powered, and sends the information to the main unit, which I velcroed to the fridge door.

Now the curing chamber is complete!  Give it a few hours to operate before you start tweaking.  Remember that your fridge will probably have its own settings for temperature, which can affect the whole system.  (I have mine set for the warmest temp.)  Here’s what the final setup looks like on the inside (completely with wild boar already curing):

Note the sensors all hanging on the center and upper left side of the pic.

The freezer above is now empty space.  And in MY converted fridge, the freezer maintains a temp of about 50 degrees, when the main chamber is 65.  50F is the PERFECT temp for aging cheese!  So I can age cheese AND cure meat in the same unit.  Don’t ever try to age cheese in the SAME chamber as curing your meat.  The bacteria that you inoculate cheese with (especially bleu cheeses) isn’t what you want growing on your meat.  So they need to be separated.

All-in-all, this setup cost me about $200.  Not cheap by any means.  But if you’re serious about making your own charcuterie and salumi at home, this is money well invested.  (A single Iberico ham or Prosciutto di Parma can set you back up to $1000!)  Some people have luck using a small college dormitory fridge, moved to the warmest setting, with a dish of water in the bottom to boost humidity.  This is way cheaper and easier to set up…but you lose control over your environment, which will yield unexpected results.  And if you’re going to great lengths to source quality meat, you don’t want it rotting away in your garage.

Now you’re ready to make prosciutto, coppa, spalla, guanciale, salami, and age your own hams.  Of course, that’s an entirely separate blog entry.  Check this out for starters!

A video will be posted soon, which may help those who are more auditory and visual.

Please feel free to comment below, especially if you already cure your own meat at home, if you have a different setup, or if you make this setup and try it.  And subscribe to my blog in the upper right corner of this page below the header image so you don’t miss out on other great posts!

77 Responses to How to Convert a Refrigerator for Curing Meat or Aging Cheese

  1. ENVY! Super cool! Maybe someday…are you certain you can use the freezer for cheese while curing meat? I was under the impression that air circulates from one chamber to the next chamber, meaning all the spores in the air would go to both chambers. No?

    • It IS possible that air will make its way between the chambers. (A HEPA filter should solve that problem, though.) I’ll let you know how it turns out.

  2. That was a great guide! Especially the wiring diagrams, I have used that temp controller on a few projects and I never remember to write it down!!

    I am currently planning a curing chamber, and I also brew small batches of beer. I noted your cheese warning, but I was wondering if you’ve ever experimented with curing meat and brewing beer in the same chamber?


    • Simon, I haven’t tried that before. If you’re talking about fermenting lager, the airlock should prevent the meat bacteria from inoculating the wort, but you WILL get beer yeast all over the outside of your meat. Which may have fabulous or catastrophic results. It will be interesting to see!

      • Thanks mate, I will let you know how it goes!

      • do you suppose one could run a small tube from the airlock and vent it outside the chamber to prevent cross contamination. i have a fridge i plan on converting for meat and cider. thanks for the write up ben, your design with the temp and humididty controllers you used make for a much cleaner looking setup than anything else i researched. I dont like building junk and the plug in controllers with all their wires running everywhere looks hap hazard. I will be using the controllers you found and fabricate an enclosure i can mount on the outside of the fridge. thanks again. nick

        • Hey, Nick! If there IS an airlock inside the fridge, you can DEFINITELY vent to the outside to prevent cross contamination. I just don’t know enough about the inner workings of the fridge to know if there’s an airlock in the ventilation system between the fridge and the freezer.

          • Hi! in reference to fermenting cider/beer at the same time as meat in the chamber. I was thinking about a tube from the airlock on the lid of the fermenting bucket vented to outside the chamber. so the yeast wouldnt burp its co2 on your meat. on another note I’ve gathered up most of the parts for my chamber and will send you some pics when get it done. thanks again. nick

  3. I found this post when searching for curing chamber designs…great post! Then I realized it’s Ben from masterchef…even better! My wife and I love the show and enjoyed watching you on it. Anyways, to my question – how have you liked this design, and are three any changes you would make? I’m about to do this same project.

    • Peter, the 3 changes I would make would depend on whether I was relying on this to be a curing chamber for meat, and using the freezer to age cheese. If the cheese freezer wasn’t a factor, I wouldn’t change a single thing. If the cheese freezer WAS a factor, I’d probably be digging around in the thermostat of the freezer to replace or remove it, because sometimes the temp in the freezer DOES drop below freezing and my cheese ends up frozen, which interrupts the ageing process. If I wasn’t skilled with electrical stuff, I’d buy the more expensive, plug and play sorta thermostat and humidity controller, so that I didn’t have to do any fancy wiring or programming like I described in the blog. But since that stuff doesn’t bother me, saving the $100 or so was worth it to me.

  4. I’m the founder/moderator for Punk Domestics (, a community site for those of use obsessed with, er, interested in DIY food, including charcuterie and salumi. It’s sort of like Tastespotting, but specific to the niche. I’d love for you to submit this to the site. Good stuff!

    • Wicked, Sean! Just tried signing up but computer locked up when completing registration. Will try again this afternoon! Awesome site.

  5. Ben,

    Is the fan running constantly or does it turn on when either the fridge or humidifier comes on? Also, what setting would you be using on the fan? Thank you so much for posting!!

  6. Pretty cool setup! Im trying to age some meat myself and have a small fridge for it. I installed a small 110v fan inside, the type used in computers. My concern is if its safe, with all the moisture, do you think it migth short-out? Thanks and great job!

    • Sergio, if you’re maintaining 6oish% humidity, I don’t think your fan will short out any time soon. But if you have no humidity control, you might be in for trouble, and not only shorts! Keep a cheap hygrometer in there to keep watch on your humidity. Anything above about 65% and you’re welcoming unwanted molds.

    • Ben, won’t the fan’s electrical cord create a gap in the rubber gasket when you close the door, allowing cold air to escape? I heard of people attaching a computer fan to the wire from the interior light, to avoid having the cord run outside the fridge. I think maybe this is what Sergio did? Sergion can you explain how you are powering your computer fan? Any recommendation on what computer fan to use?

      • David, there is a very small gap. Because the temp in the fridge is fairly close to the ambient outside temp most of the time, it’s not a vast energy loss. I have the whole setup attached to a killawat which measures energy consumption…and it’s very, very low. Less than $15 a year based on energy costs in my area. Please note that the temperature and humidity probes for the controllers must ALSO go from the outside to the inside. So you’re going to have cords going in there, regardless. If you wanna get brave you might try drilling through the side of the fridge, but you may puncture a coolant line.

  7. Aaron Hernandez

    An FYI to those,like me, who chose the plug n play method: the humidity controllers that Ben has suggested are not the right type. In Ben’s instructions for installing his own hard wired humidity controller, he mentions programming his controller to a max/min humidity range. The suggested controllers for one, don’t have a probe that can be placed inside the fridge, and two, can’t be programmed to humidify a set range, ie from 60-70%. In fact, in my searching, the only humidity controllers that have a “hysteresis” function, are non-plug n play. I’ve spent weeks waiting for my controller to come in, and now I have to send it back. Be warned.

    • Aaron, thanks for your input, and I’m sorry if I recommended something that didn’t work for you. A friend of mine in Wyoming told me that he used that humidity controller to build his curing chamber, which is why I recommended it.

      • Aaron Hernandez

        Dear Ben,
        A follow up to my somewhat negative comment: after months of trial and error, sadness, anxiety and IMPATIENCE (lol) I have finally produced my first charcuterie product: hot copa!! It looks not like I was expecting, but as my first attempt, I’m absolutely thrilled!! It’s delicious! De-lic-ious!!! Thank you for making your DIY guide/article available to the masses! This will be a worthwhile addiction!! Thanks again!!

        • Aaron Hernandez

          P.s.- a little advice to those, like me, who live less than a mile from the ocean:: I use a humidifier and de-humidifier in my chamber. I was having an extremely difficult time controlling humidity being that it is always 70-100% humidity here in Northern California. And on top of that we’ve been having an extremely dry winter mixed with rodents of rain, which threw evertything out if whack including my chamber. Hence, I needed both the humidifier and dehumidifier. Good luck!!

          • Barry Wayne

            Aaron–what humidity controller are you using to control both humidifier and dehumidifier?



        • So glad you’re enjoying your hot copa! That’s one of my favorite cured meats. Mmmmmm…

          • Aaron Hernandez

            Doc– (I really hope you get this as I’m unsure wether or not I’m ‘replying’ in the right place….?)

            I searched many sites for a control box that would be able control both my humidifier and dehumidifier, but alas I came up empty handed (though I can’t say for sure that it doesn’t exist). So what I’m using are two Dayton brand controllers; one for the humidifier and one for the dehumidifier. Needless to say, my dry box is housing more electrical components than actual meat products. Doh! Hope that helps!

  8. Hi
    I live in the UK where most things American cost the earth, if not in the purchase price in the postage costs. Despite this I am definitely going to try this. I have a great interest in DIY food preservation and making my own home-cured ham etc would be quite an achievement; so thanks for the post.

    T Counley

  9. Hey Ben,

    I used your wiring diagram to try and setup my WH8040 and for some reason the unit is giving me an “EEE” error on the LCD screen. The only difference between my setup and yours is that I have 1 and 2 wires hooked up to a socket that I am going to plug into my humidifier rather than running it in directly. I have some photos of my setup but couldn’t figure out how to post them here in case a visual would help.

    Thanks for your help

    • Erik, I’m not sure why you’re getting the EEE. Is it always displaying that, or only when the humidifier is plugged into the socket? If it displays it constantly, which is my guess, it has something to do with the resistance of the socket and the fact that the WH8040 is trying to turn on the humidifier, but the circuit is broken at the outlet. I would direct-wire that humidifier, if I were you, and see if it works.

  10. Hi Ben, just wanted to say your post really got me going on making my own curing chamber. I just wrapped up and my friends asked me to chronicle the build so I’m going to be posting daily for a couple days. Anyways I’m referencing and linking your blog at several steps along the way because of how much it helped. Thanks for the great work and keep it up.

    • Thanks so much, Tyler! Good luck on the modification, and let us know how it turns out!

      • Worked out so great, I’m having a little trouble with the humidity being too high right now, (we’ve had a lot of rain in SF recently) but the project turned out great. I’m starting with some Duck Prosciutto right now which I’ll have a description up of soon. Plus I have plans to go wild boar hunting in a few weeks so I can get started on prosciutto and pancetta, maybe even some salami if I add a grinder/stuffer to my pantry. Again here is the link A commercial fridge sure looks good despite the hassle.

  11. Nice article. There seems to be an error in it that could cause trouble, however. To guarantee maintaining your set PID controller temperature, you should set your refrigerator temperature to the coldest, not the warmest setting. If, for example, you’d like your chamber to maintain 50 F and your fridge’s warmest setting is 55 F, the chamber will never be cooler than 55 F even when your controller is set to 50 F because the fridge thermostat will stop the compressor before the PID controller reaches the cutoff temperature. If the fridge temp is set to its coldest value, it will continue to cool until the PID controller reaches its set value and cuts off the power. That way you know that the compressor will always kick in when the chamber is warmer than the set PID value.

  12. Hi Ben,
    I just built a chamber almost exactly as you have done. I used a tall Bosch frost free larder fridge, same controllers as yours. The problem I have is not one I expected and wondered if you or any of your readers have come across this. The problem is my humidity level is too high, the humidity controller never kicks in. I even turned the US humidifier off. The Humidity level is running at circa 80-85% practically all the time, not surprisingly it drops when I open the door but it very soon climbs back up again. The temp is controlling fine and the ambient humidity in the room is circa 50%. I expected the fridge to run at much lower humidity. Any ideas anyone?

    • Hi, Simon! Very strange, but I’m not familiar with a “frost free larder fridge.” No fridge should be frost-free, because a refrigerator doesn’t get below the freezing point. If you are trying to use a converted freezer, most conventional freezers do not have an evaporator feature that lowers the humidity level automatically. However, “frost free” freezers do have this feature. Ultimately, though, I’m not familiar with the type of refrigerator you’re using, so I can’t really comment. A traditional fridge/freezer combination should give you extremely dry conditions which you have to supplement with extra moisture with the humidifier. I’d ditch this “frost free larder fridge” that you have, and find a cheap or free used, traditional fridge/freezer combo.

  13. Hi all, just to let everyone know that I followed up on the loaclfoodheroes article re humidity too high and I added a small heat source in place of the humifier. Bingo, the humidity is now tracking 75 +/-5% & temp tracking 10.5 – 12.5 as set. I suspect that come the summer months I may need to ad the humidifier back in but we will see. Just tried first batch of salami, yum.

  14. I don’t know what humidity levels you hope to reach, but 70%+ at 57 degrees F is a pretty good target for most cured meats, allowing the water activity to diminish slowly, especially for fermented salumi. The reason most home curing chambers fail is lack of fresh air, which will create the perfect environment for bad mold, bad microflora, bad aroma, bad taste, and potentially hazardous product. Look to simple solutions like a computer cooling fan on a timer, running for just a few minutes per day. Simpler still, just open the door on your chamber 2-3 times a day for a few minutes. Look to the old world if you want to understand what curing is, and what it is not. Nobody in the old world cures meat in a sealed space, and certainly not in a space the size of a small refrigerator. You can tell yourself that the funky aroma is “old world”, but it is not. Cured meats need to breathe. If they do, they can handle a fairly broad temperature and humidity over the course of a day.

  15. OK i don’t cure meat im in the cigar business and was having problems with my humanist came across your diagram on amazon linked here. thank you. i have two off these running two humidifiers and they work great also picked up the temp prob. you rock…..

  16. Question – I want to hang whole beefs so of course need a lot more size. I understand that cooling units in fridges are based on the cubic footage of the fridge and my closet will be bigger. Can I make up for the larger size with a much higher insulation value?

    • Jim, this is uncharted territory for me. You’re wanting to convert a closet into a ageing chamber? I would imagine that, with a window unit or portable a/c, you could easily keep the room temp in the right range (though your electricity bill will certainly go up!) Keeping a room humid enough (or dry enough) may be tricky, depending on where in the country you are. And, yes, I would encourage an insulation boost on the walls and ceiling of the room to lower the amount of electricity you have to use. Sanitation may be a problem since you can’t just spray the inside with Lysol after use. This project will require LOTS of research.

  17. Did you repurpose a freezerless fridge or maybe you removed the partition between freezer and fridg?
    If it had a freezer would it matter if it was top, bottom or side-by-side?

    • Don, if you are repurposing a chest freezer, it may end up being too damp on the inside. I have converted several chest freezers into refrigerators, and they produce a HUGE amount of condensation. This is a traditional fridge/freezer combo. The freezer part stays around 50F when I’m actively curing meat in the fridge portion, so I use the top part for ageing cheese. When I’m not using the bottom for curing meat, I leave the freezer part so that it freezes and I keep frozen stuff in it.

  18. Hi Ben, thanks for the great info. I have an old beer fridge (I’m in Australia) which I think would be perfect to convert to a curing chamber as it has a bottom mount freezer. BUT, it says it is ‘cycle defrost’. It appears to have a cooling plate in the fridge compartment which frosts up and periodically warms to remove the frost which melts into a channel is passed out of the fridge. Any idea if this will work as a curing chamber? Or will it run too humid, especially when I put meat/salami in there? Have ordered a thermo hygrometer so will be able to check it soon. Thanks.

    • Lomas, others will probably be better equipped to answer this question than I am…I’m not that familiar with how refrigerators and freezers work. MOST fridge/freezer combos here are “frostless” which means they do that thing where they warm up slightly and circulate the air to get rid of frost crystals. So I think you’ll be just fine.

  19. Question about the WH8040. I’m setting up a unit with a humidifier and dehumidifier with a WH8040 controlling each one. I’m having trouble wrapping my head around what the settings for each unit should be. Let’s say that I want humidity to be at 70%. Would I set the humidifier unit to come on at, let’s say 67%? And the dehumidifier to come on at about 73%? Also, what where should the hysteresis be set? I guess I don’t want to be continually cycling between the humidifier and dehumidifier. Last question: Could one sensor be used to feed both WH8040 units (ie could I make pigtails at the ends of each sensor wire and then connect them to each WH8040)?

  20. thanks for wiring help on the humidity controller. can’t help but mention tho – always make yr wire loops clockwise so that the nut tightens them rather than loosens them. they really do come loose if done backwards… you’ve got yours backwards on the photo with the fridge plug :)

  21. Hi Ben, i was curious if i built a non-ultra sonic, cool-mist humidifier into the door of the fridge if it would work. My plan is to use either the same material as the inside of the fridge or glass/plastic and use a water proof sealant to make the door all one chamber. Leaving a corner out for where the fan goes. The fan will be part of the lid to easily change the filter and add more water. If this system works then ill be able to have all my electrical wires in the door other than the sensors. Also it’ll never be in the way.

  22. I note that you are recommending a humidity of about 65% and a temp in the low 60′s. Articles read of hanging beef carcasses recommend 36-38 degrees and initially humidity of 85-95%. What am I missing? I took your word “curing” as the same as “aging” but I think I misunderstood.
    In a response to a question I asked earlier you thought my aging closet was too big for the fridge to handle but as I look at the unit in your pictures it also seems pretty big. Mine is 5X5X7 with 5 1/2″ insulation. I want to use a fridge/freezer because AC units seem to have a lot of problems with the coils freezing.
    By the way, I really respect your ability to say, “I don’t know.”
    Jim Wolf

    • Jim, my humidity recommendations come from the Italian traditions as documented in several books which started me on my meat curing journey. Aging beef and curing beef are two VERY different things, though!!

  23. I’m in the process of building my chamber, just waiting on my stc-1000′s to arrive. being a little anxious I was wondering if you could tell me; can the stc-1000 operate on cooling & heating at the same time. Such as it cools to 55f but if temp drops below 50f the heat would kick on. Or is it just one or the other?
    By the way, I have studied your post and I’m using many of your designs on my chamber. Thanks for sharing.

    • Mike, I don’t use mine for heating, only for cooling. So I’m not sure what to tell you, though lots of other folks have been following this thread that know way more than I do! I personally don’t think you need heating unless your unit is in a garage in an area that gets really, really cold. Move it indoors to a closet for the winter?

  24. Hey guys you may try a hydrate unit designed for a humidor, they work well and are self contained but the cost is a little expensive. I am building a unit just for my artisan cheese. I am using the same temp control suggested but wiring it in place of the factory thermostat. Most factory thermostats on mini fridges turn power to the compressor on and off so with a volt meter figuring out the wiring is easy. This keeps the wiring in the box.

  25. Hi Kevin. Where did you get hydration unit? I am doing the same. Trying to figure out how to maintain thee high humidity need.

  26. George Drndarski

    Hi Ben Thanks for sharing. I started 2yares ago ewriting works great I want to expand My production I wont to no if I could convert a chest freezer for a holding chamber the refrigerator is only for curing I haw no room for finished product I think they do interfere with each other On your design I made 1 small change I put the humidifier outside whit a hole on the side of the refrigerator works great thanks George

  27. Most modern residential refrigerators work by making coils (evaporator) cold in the freezer with a fan circulating air in the freezer. Some of that cold air goes into the refrigerator portion of the box. The fridge and freezer are not isolated, because there is active ventilation between the compartments. The freezer does not become a separate compartment as you have assumed. If you are trying to isolate your aging cheese from your curing meat using a residential fridge will not work without major re-engineering. I plan to use an upright frost free freezer for meat curing in batches. Commercial dual zone refrigerators operate differently.

    I am also curious to know if a dehumidification override would be required for humid climates. Frost-free fridge/freezers dehumidify as part of operating. It is relatively simple to set up, but adds the expense of another controller.

    • Brian, you are correct that the same air circulates between the fridge chamber and the freezer chamber. I’ve just placed a HEPA filter over the air vents to try to keep down the bacterial flow between the two chambers.

  28. Very interesting!…I want to make my refrigerator a maintenance unit for fruits.So I want a temperature 2-5 Celsius and humidity 90-95%..CAn I do it with your DIY unit?..Thank you

    • Yes, this setup can be used to keep your fridge at virtually any temp from just above freezing to several degrees below the ambient temperature of wherever the unit is kept, and any humidity level.

  29. I just got all this rigged up. But what do you do if the refrigerator is in a cold place (45-50 degrees)…is there a way to set up the temperature controller to heat when it gets too cold, or is the refrigerator being too cold not a bad thing? Will that affect meat?

    • Ben, I don’t live in a climate where the fridge would ever get below that temp for more than a day or two. Your fridge is insulated from the inside out, so if it’s colder outside, the inside is likely to remain in or close to your target temp zone for quite awhile without the compressor having to turn on. However, if you’re in a climate where your garage sits at 40 degrees all winter long, you might need to consider a heating element. Just remember that, for millenia, humans have cured meat in underground cellars, which DO fluctuate in temperature throughout the year. Meats will STILL cure at lower temps, they just take longer to cure because microbial activity is slowed. I’m not enough of an expert to know if your recipe would need to be modified if you’re curing when the temp is 45 degrees, but in Iceland and Greenland they cure meats in near-freezing temps all year long.

      • Makes total sense Ben. So do you know if the Johnson Controls Digital Thermostat Control Unit (this is what I’m currently using) will automatically “turn on” the cooling once the temperature *does* increase to a certain point?

  30. Question: I’ve got the Johnson A419 Temperature Controller…does anyone know the jumper positioning settings I would need to have this on to enable the refrigerator to go into cooling mode when temperature exceeds 65F and to go into heating mode when the temperature goes below 60F?

  31. Read the whole blog, then all the comments! Have a question: I’m looking to convert an old standup freezer. Will that work instead of a fridge? I’m not real wire-savvy so I plan on using the plug-and-go setup. I saw someone commented that the humidity controller doesn’t actually work in this setup – is that true?

    • I’m not sure why it wouldn’t work with an old standup freezers. Your only problem may be excess humidity, as most chest and upright freezers don’t dry out the air the way that fridges and frost-free freezers do.

  32. Have you ever used the fridge to dry-age steaks or any other curing process? If so, did you still need to use the humidifier or would that necessitate the addition of a dehumidifier? How much lower was the humidity of the fridge without the use of the humidifier versus the ambiant humidity in your area?

    • Steven, our humidity is typically in the 50-60% range, and my normal fridge is around 70% humidity, depending on what I have in it. (It’s normally quite full of stuff…emptier fridges will be drier.) Dry aging needs the same humidity range as curing…80-85%. You’d need to test your own fridge in your area in your season to determine if you need the humidifier or not. I doubt you’d need a dehumidifier unless you’ve crammed the fridge absolutely full of meat.

    • Kevin Blanchard

      Steve Ben is correct another varience is where you live. I live in Oklahoma now and I need a humidifier but when I lived in Louisiana the relitive humidity was higher and it reflected in the fridge as well.

  33. My wife has been after me for years to make one for making charcuterie and I’m ready to give in. Mostly because I’m hoping this will work for curing all the sweet potatoes I have in the garden.

    Here’s my question: will I be able to reach 80 degrees to 85 degrees and a relative humidity of 80 percent to 90 percent? That’s quite a bit higher, on both counts, for normal curing. Any ideas on modifications? Maybe a heating pad with the fridge turned off. It’s only for a week or so, then back to normal. Your thoughts?

    • Interesting question, Tim. I honestly have no idea if a heating pad will produce enough heat to keep the chamber above 80. (Certainly if you live in a hot climate, like I do, you wouldn’t need that in the summer, depending on where you locate the unit.) All the modern heating pads I’ve run across turn themselves off after awhile, so if your unit was having trouble keeping the fridge up to 80F, and the pad was on the whole time, I think it might eventually shut itself off. My suggestion would be to do your curing in the heat of summer, when your garage or backyard is always 80F or higher, if you live in that sort of a climate. If not, it might be worth trying the heating pad, but I’d imagine a small space heater would be more efficient.

  34. Fantastic post! Your wiring instructions for the WH8040 are a godsend. I am using it for mushroom production but intrigued by this topic!

    Quick (hopefully) wiring question for you, Ben. I would like to run a fan and humidifier as a single unit or at least concurrently controlled by the WH8040. Could I pigtail them to slot 1 and to the neutral wire of the power cord? Should I plug them into a multi-outlet cord and run that through the controller? What’s the best/safest way to do this?

    • Sebastian, that sounds logical, but as I’m not a professional electrician, any advice I give would be complete speculation with very little actual knowledge of any danger that might create. Maybe someone more electrical savvy will chime in!

      • Thanks for answering, Ben. I ended up speaking with a sparky about this, and his recommendation was to connect the WH8040 to a regular outlet that I could then plug the fan and humidifier into. So the outlet is wired into slot 1, etc… and the controller shuts off power to the whole outlet. Kinda clunky, but it works!

  35. Anthony Davis

    Hi Ben,
    Thanks for the inspiration. I have just finished my fridge conversion and built a control box. My humidity controller is the WH8040. The problem I have is trying to achieve 85% humidity. I have a strong suspicion the 8040 humidity sensor is getting saturated and drifting off by as much as 20%. It routinely overshoots to ‘HHH’ (99%) although my data logger shows the true humidity rarely gets to 80%.
    Have you come across this problem? Do you know if other types of sensor are available which can handle high humidity?


    Tony (UK)

    • Tony, I haven’t had this problem, so I’m not sure what to tell you. This sensor worked for me without any issues, and my humidity sensor shows it to be pretty spot on…