If you chose to build a “room temperature” refrigerator please read and observe all warnings on the products and tools. If you drill the hole for the wires be careful about any sharp edges to avoid cutting yourself and/or nicking the wires. If you buy a new refrigerator for this project drilling the hole will void your warranty. You will need to consider your skill set and if this project matches those skills. If you are uncomfortable doing any step please do not attempt or get someone that is competent to perform the step.
Recipes call for ingredients to be at “room temperature” but rarely indicate what temperature that is. In the summer my kitchen is somewhere in the mid-seventies. In the winter in the sixties. From experience my cookies come out differently depending on the season.
Digging into various sources the temperature most referenced as “room temperature” is around 65 degrees (18C). This is mostly based on butter. Above 68 degrees (20C) butter starts to lose its ability to be creamed incorporating air properly. Once butter has gone above 68 degrees, we can’t get that ability back.
To ensure ingredients are at the same temperature each and every time we need to control the environment beyond putting them on the counter X minutes ahead of time, putting in microwave for X seconds, or under a heated bowl for X minutes.
I researched to see if anyone made something that would maintain 65 degrees. My initial thought was to look at wine refrigerators. Almost all of them did not go up to 65 degrees and depended on the room being warmer than the temperature you wanted to hold at. Some really expensive ones did go to higher temperatures but even most of them depended on the room being warmer than your target temperature. These work by cooling when the temperature was too high and allowing the surrounding room temperature to warm things up if too cool.
If we just set a refrigerator at 65 degrees it might work when the room temperature is above 65 degrees. But if the room is cooler than 65 degrees the refrigerator will stabilize at the room temperature since it can only cool. Most refrigerators can’t be set to 65 degrees to begin with though and we need a way to add heat if needed.
So, I built a “room temperature” refrigerator. I got the idea from beer brewing websites that need to keep beer at the right temperature for fermentation. To maintain the right temperature regardless of the room temperature a heating source is added to raise the temperature when below the target temperature.
We need a refrigerator, heating source and a temperature control device. The temperature control device will turn on the refrigerator (cooling) when the temperature gets too high and turn on the heating source when it gets too low. Adding a fan ensures there are no hot or cold spots along with speeding up the process. These are the items I used.
Outlet Strip
Obtain a small college room style refrigerator. You might already have one or can find one on Craigs list for about $50. Don’t need to go crazy with getting a top of the line. If possible, pick one that has grill style shelves for better air flow.
The Inkbird temperature controller has two outlets, one controls the cooling device and one controls the heating device. The cooling device is the refrigerator, the heating device is a heating pad designed for beer and wine fermenting. If the refrigerator is located in a room that is warmer than the target temperature the temperature in the refrigerator will gradually rise until it hits the upper limit. For the recommended setting the upper limit is 66 degrees (19C). The refrigerator will kick on and lower the temperature, since the refrigerator is much better at cooling than the heating pad is at heating it will quickly lower the temperature to the lower limit of 64 degrees (17.7 C) over shooting it causing the heating pad to kick on. The heating pad only uses 12 watts so the temperature will rise gradually until we get to 65 degrees and the heating pad turns off. There will be some residual heat in the pad but it won’t typically push things to the upper limit. As long as the room isn’t too warm it will take a while before we need cooling again. By adding some bottles of water, the oscillation between heating and cooling is moderated a bit. Also, since the items we are bringing to room temperature are cool to start with the temperature will tend not to rise much.
Note: You can skip this next step of drilling hole and just feed the wires through the open door and when you close the door position the wires so they lay flat under the magnetic strip on the door. You will need to do this each time you use unit.
Locate a spot in back or side of refrigerator where no wires or pipes pass. (see safety note above) The back will give the best-looking setup. For mine I was able to find a spot low on the back. Drill a hole large enough for cords to pass through and with space left over for insulation. A standard hole saw may work but it will likely be useless when you are done. A ¾” electrician hole saw works great but is about $40-50.
Feed the wires for the fan, heating pad and temperature sensor through hole. Be careful of any sharp edges. Using pipe or other insulation fill in the hole, ensuring the wires are in the middle of insulation away from edges of hole. You can use spray foam if you like, that means any change of equipment will require the spray foam to be dug out. Not that hard but something to consider.
Use the screws that come with fan as legs. Position fan on bottom of refrigerator so that it blows the air up, you may need to move it around to find a location that it doesn’t vibrate. Only matters if the noise is a concern.
Using shelf grate clip position the temperature probe on shelf above fan. Depending on your shelf grill you may need to bend/deform the clip to make it fit. If your refrigerator does not have grill style shelves find a place that you can mount/tape the sensor so that it is in the air flow from the fan.
On side away from fan lay several personal sized water filled bottles on their side and then stack two in-between and if enough room one on top of these to make a pyramid. The grill should allow you to pile them up without the bottles rolling. These serve as a mass that helps moderate the temperature swings. If you have room adding more bottles will help.
Position the heating pad under the bottles. I fashioned a support so that the pad is at an angle and isn’t just laying on bottom so that more of the heat is transmitted into the air and not the bottom of the refrigerator. It is a piece of plywood with holes large enough for a wire hanger wire to fit and bent into loop to support pad. If the pad was smaller, I might have put it in the air stream from the fan. But given the small space and the fan capacity I figure the air is getting stirred up well enough that it doesn’t matter.
For the Inkbird control I attached it with a screw to the side of the refrigerator, you might just lay it on the top. Plug the fan and Inkbird into outlet strip. Plug the refrigerator into the cooling plug on Inkbird and the heating pad into the heating plug.
Turn the temperature control in the refrigerator to maximum cooling. The Inkbird will control turning it on and off. Follow directions for Inkbird to set your desired temperature.
I set the temperature target to 65 degrees with a 1-degree window up/down. When it gets to 66 degrees it will turn cooling on, turning off when it gets to 65. When it gets to 64 degrees it will turn on heating, turning off when it gets to 65 degrees. The cooling cycle will turn off at 65 degrees but the refrigerator will continue to cool and may go below 64 degrees triggering heating. Heating doesn’t typically overshoot on the high side. Once things settle down the cooling overshoot will be minimal and since it is on the cool side our butter doesn’t suffer.
The room mine is in is 55 degrees in the winter so the temperature tends to be between 64-65 in winter. In summer room can be in the seventies so the range is 65-66. In winter time the cooling cycle rarely runs. In summer both heating and cooling runs due to the cooling having much more overshoot.
Place butter, eggs and other things you want to be at “room temperature” on shelves above fan. Typically, I just lay them on the shelf, not in a bowl. Shelf grill keeps them from rolling around. If you did put them in a bowl it probably will take a little longer for everything to stabilize temperature wise. I have mine away from my kitchen so I take things in a metal bowl to transport them. After putting the items on the shelves, I put the bowl in the “freezer” section of the refrigerator. Your model refrigerator might not have a “freezer” section. This way the bowl in the summer time is also at room temperature while I transport the items back to the kitchen. Unlikely to really make a difference so in reality it is just a convenient place to put bowl.
This approach does require some advance planning to have the ingredients ready. I try to put things into the refrigerator about 4 hours before I plan to bake. I haven’t done tests to see how quickly ingredients stabilize but my guess is 2 hours should work with the fan helping. Ideally, I put them in the night before so I don’t forget. With that said always take into considerations the go bad time frame for ingredients, milk for example shouldn’t sit out for more than two hours before use. You don’t need to run the refrigerator all the time, I will turn it on as I put the items in and off when I take them out. If the room is warm the cooling will turn on right away so the butter won’t get above 68 degrees.
But you can leave it on all the time if you like, unless your refrigerator is in a really hot place it won’t cycle that much. In the summer it will run the cooling cycle for a few minutes and then the heating cycle for a few minutes. This might happen once an hour depending on how warm the room is. In the winter time, the heating cycle typically runs for a few minutes.
Since setting up my “room temperature” refrigerator I have noticed a vast improvement in the consistency and quality of my baking.
Like!! I blog quite often and I genuinely thank you for your information. The article has truly peaked my interest.
Glad that you like this, it has made baking quite a bit easier for me. Let me know if you have any questions