How did Shabbos mode come to be—and what problems was it actually designed to solve? Rabbi Shmuel Katz, Rabbinic Coordinator at the cRc, joins R’ Yitzy Hisiger for a fascinating look at the history, halachic challenges, and ingenious solutions behind the Shabbos modes in today’s appliances.
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Transcription
Hello everyone and welcome back to Let’s Talk Kashrus,presented by the Chicago Rabbinical Council. Today I amjoined by Rabbi Shmuel Katz, Rabbinic Coordinator at theChicago Rabbinical Council. Thank you, Rabbi Katz, forjoining us once again. Thank you.
The last time we met, we spoke about the concept of Shabbosmode, and you gave us a beautiful primer about the workingsof Shabbos mode, halachically, practically. What I’d like todiscuss with you today briefly are some of the issues thatShabbos mode came to address. I think it would be interestingto go back historically to when the original oven shailosarose. What were the issues that were discussed by theposkim, and how did Shabbos mode address those issues? SoShabbos modes were started only in the last 30 years, but theshailos have been about 100 years old.
And the shailos, the tshuvas really started with the thermostatson fridges. This was an electronic appliance, and peoplediscovered that it had a thermostat, which meant when thetemperature in the fridge gets too high, it turns the fridge backon to cool it back down. So people opened the fridge, the coldair would come in, it would make it warm and it would causeit to go on. And the poskim discussed: Can you cause thefridge to go on on Shabbos when you open the door? Can youopen the door and allow it to happen? An oven’s was the samething.
It had a thermostat. You open the oven door, the cold airwould go in, it would cause the temperature to drop, the firewould then go back on to do it. Ovens as well, if you open theoven door, even if the flame is on, the fire would stay on forlonger because now it needs to stay on for longer, like beingmosef shemen, which is a problem on Shabbos. Is that mosefshemen? And is your action of opening the oven door directlycausing this? So Rabbi Shlomo Zalman has many tshuvas, andis probably the original of the heterim to open the fridge onShabbos even when the compressor’s not on.
So some solved this by just waiting for the fridge to turn on.Only when the compressor was on and it was rattling, wouldyou open the fridge door because then you’re not causing it togo on, it’s already on. And the same thing with ovens, wouldonly open the oven door when the fire was on. This is whatbecame…
there were people who were being meikel and wouldn’t worryabout this shaila because of their rabbonim, and the ones whowere machmir were very often just waiting for the compressorto go on or the fridge to go on. And that was the originalShabbos mode. You just spoke to your rabbi, you knew howto use it in a way that’s appropriate for Shabbos. And thenabout 25, 30 years ago, the appliance manufacturers weretapping into this and working with, and the Star-K was a realpioneer in Shabbos modes to solve Shabbos problems.
Originally at that point, they were focused more on more newproblems, not related to the old ones. So some new ovens,after 12 hours they would turn off. Who leaves their oven ontwenty-four, for 12 hours? After 12 hours it would go off, andthat would be a problem for Shabbos or Yom Tov for sure ifyou needed to keep it on. Another very practical thing, butpeople would like their oven to go off Friday night, set thetimer so it turns off Friday night after your food’s done.
So ovens come with a time-bake feature where you can set atimer, but almost all ovens they beep and they continuouslybeep after the timer ends, which would be very annoying onShabbos to have the timer beeping the rest of Shabbos, andShabbos mode would disable that. So there was a couple ofthose practical types of things that the Shabbos mode wassolving. Then lights became common, and Shabbos modevery often were also able to solve the light. Fridges also theShabbos mode came to solve a bunch of problems.
One of the probably biggest problems, besides for the light,those don’t turn off after 12 hours like ovens do, but there’s adefrost in the back of the fridge. It builds up ice, or frost-freeare fridges. In the old days you had to manually defrost yourfridge. Ours are frost-free, gratefully we’re not dealing withthe ice build-up.
But the way it does is it turns it off and it puts a heating,there’s a heating element in there and it gets red hot. Itactually, which we, which is esh. There’s fire in there. Soeventually there’s a fire going to go on in the back of yourfridge, a halachic fire for Shabbos purposes, that’s going tomelt the ice off.
So the question was what triggered that to go on and off? Soin more recent models, again, recently not in the last fewyears but in the past decades, they’ve put those on, they wantto do it efficiently, so they started doing it by how often thecompressor runs. After a certain amount of time thecompressor’s running and the fridge is cooling, it assumesthere’s a build-up and it will go into defrost mode. Anotherthing they would do is count how many times you open thedoor, because humidity affects how much humidity’s in thefridge is going to affect it, and that’s going to also depend howmany times you open the door and let in ambient air into thefridge. So it counts those door switches.
So eventually you’d open the door a few times, let’s say it’severy tenth door opening, you’ve that tenth one, you’veopened it and it said let’s turn on the defrost, and that’sactually a de’oraysa shaila because it’s an actual fire going onin there. So the Shabbos modes almost universally solve thatby Putting it on a fixed timer. It goes on every so oftenautomatically, unrelated to how often the compressor’srunning and how many times the door’s been opened. It’s beenable to solve some of those as well.
It’ll disable Shabbos modes will disable the buttons so almostall the buttons won’t work on your fridges and on your ovenor at least when you push them nothing will happen, nothingwill be visible from it. So they’ve come to solve a lot of minorissues and then some practical issues and then some halachicissues as well. The Shabbos modes have become very helpfulfor. Got it.
Any other issues that you wanted to discuss as far as theShabbos mode addressing? We discussed thermostats, youdiscussed the the defrost right. So the door switches is alsosomething we discussed in the last episode. We discussed lasttime yeah. The door switch and what the door switch does.
But just to go back to the pre-Shabbos mode days of thethermostat to discuss that for a minute. Rav Shlomo Zalmanwas talking about in his teshuvas. He’s talking about a veryold thermostat that they would use then which had a capsuleof gas of liquid. If it got too warm it would expand into gasand would blow up a what was called a bellows which isessentially a balloon.
And that balloon would physically push a button to contactand turn the oven on or turn the fridge on and then it wouldcool, it would go back into liquid, it would shrink and then thecontacts would come off and that’s how the compressor wentoff. So this was a very physical physical manual of sortsanalog version of a thermostat. Thermostats have come havechanged quite a bit. Our current thermostats in ovens andfridges have no moving parts.
There’s just a little bit of metal in there. The computer’ssending an electrical signal through what is a thermistor andit’s and measures the resistance of the electric through it andthat resistance changes based on temperatures. It’s veryminute. It changes very slightly but these are super sensitiveand they can pick up the slightest changes in temperature bysending electricity through a piece of metal and seeing how itcomes out the other end.
They can detect it so it’s it’s an entirely different thermostatthan Rav Shlomo Zalman was ever talking about which doeshave halachic ramifications and the poskim and the certifiersof Shabbos modes work very closely with to figure out. SoRav Shlomo Zalman was was meikel in certain scenarios.There were machmirim but since then the Shabbos modeshave said hey we can actually solve we might be able to solvethe thermostat problem as well. So besides for making it aslike an old thermostat or at least as good as the one thatShlomo Zalman was being mattir, they said we can solve itentirely and various attempts have been made at figuring outhow to solve this.
Some some super creative. Some people were just puttingtheir fridges on timers. You put your fridge on a timer it thewhole fridge goes off every 15 minutes for five minutes andwhile it’s off you quickly open it and close it and you takewhatever you want out. It’s not very good for the new fridges.
The new fridges have a computer in there and they have verystrict cheshbonos on how they operate and when they do so itfor the new fridges. Would it be good for it to be going on andoff randomly? It’s terrible for the fridge. The new the newfancy fridges it’s completely terrible for but this is whatpeople were doing. The old fridges could handle it becausethat’s kind of how they were built anyways.
They were just unplugging and plugging themselves in withthe bellows. But the new fridges they can’t they’re not built forit so you’re really going to reduce the life of your fridge if youdo something like that. Even taping down your door switchthe whole week is bad for the fridge because they they builtthe fridge to be to rely on that feedback for various functionsand and the experts say it’ll reduce the life of your fridge ifyou keep it taped down the whole week. It may not even coolproperly because it’s it relies that when it’s the door’s open itwill know it.
So over Shabbos it’ll be okay but over to do it the whole weekand just leave it like that permanently on the newer fridgesthey say will reduce the lifespan of your fridge. So the theways to solve the thermostat we started with putting it on atimer some people were doing and then the agencies gotinvolved and they were able to work with the work with themand and come up with creative solutions. So some of themhave where they put it instead of constantly taking thetemperature and knowing and then immediately acting uponwhenever there’s a change in temperature to turn the theappliance on or off it goes it’s set to go on at fixed intervals.It’ll take a reading right before it goes on to see if it’s off abase if it’s out of the window but instead of an immediateevery every few minutes it’ll take one it’ll be set to go on andthen it’ll just take a baseline reading to see if it’s off base andneeds to skip that one.
That’s how some solved it. The new Shabbos mode they dosomething very fascinating. They take the ambient airtemperature. Instead of taking the temperature in the oventhey’ll take the temperature outside the oven and they’ll knowbased on the temperature outside the oven how often the fireinside needs to go on or off.
Interesting. Another another solution some came up with wasto let the oven remember from during the the fridge rememberfrom during the week. We know that in your house this is howoften the fridge the compressor needs to go on to keep youritems cool because we’ve measured it the whole week. So it’sgonna vary from house to house and appliance to applianceand use person to person depending on how you use it.
So it depends on the person, your usage of it, depends on theenvironment around it, depends on the ambient temperature inthe room, the humidity, all things, so if you just measure thatduring the week you can now know pretty well how oftenyou’re gonna need to go on and you just skip the thermostatentirely and on Shabbos only use go based on a fixed timecycle that you’ve determined by using the week beforehand.So there’ve been some creative ways that the Shabbos modeshave been able to solve the thermostat shaylah and make theovens and fridges even better than they were when the tshuvoswere started to be written about a hundred years ago and thosetshuvos when they were struggling with the thermostat BaruchHashem they’ve some of them have been able to solve it in away that’s way better than we’ve had in the past but again thisvaries from model to model, it varies from certifier to certifierand type of Shabbos mode to type of Shabbos mode it’s gonnavary. So to know what you actually if you’ve always beenmachmir on the thermostat shaylah you’re gonna want toknow how your current one works very specifically with yourspecific model to make sure that it’s changed enough for youto change the way what you’ve been doing in your house untilnow. Got it.
Okay, so you know the bottom line is if you have whateverappliances in your house you have to make sure that you’refollowing the proper protocol and people who are buyingappliances in addition to finding out the features, the model,the price you have to find out the halachic ramifications andcomponents and get proper guidance so that it addresses someof the issues that you spoke about today that Shabbos modewere designed was designed to solve. Yeah. Right, and I wantto add that it is very important if you have an appliance inyour house to find out how it works but it’s also crucial ifyou’re going to buy an appliance understand how you want touse it and figure out if this is what you want to do with it andwhat the right model for you is. If you don’t intend to everkasher it for Pesach then don’t worry about kashering it forPesach when purchasing your model.
But if you do you may want to know that in advance. Here’sanother example on ranges. Induction burners are verypopular right now. A lot of houses they’re neat, they’re sleek,they might even be safer because they don’t get hot.
But if you have non-Jewish domestic help they’re terriblebecause you can’t turn the fire on and let them put a pot on thestove anymore as Ashkenazim because there’s no fire there. Soif you have non-Jewish you don’t want to buy an inductionburner if you have because then you have to actually put thepot on the stove for them. You can’t just turn the fire on andlet them go induction burner. So it’s worth pre-purchase walkin don’t buy the sleekest model and then afterwards call yourrav and say how do I use this on Shabbos? Figure out howyou want to use it and then go buy a model that fits yourneeds in the best halachic way possible that matches yourneeds as well.
Excellent. Rabbi Katz thank you this has been a tremendouslesson in the workings of our home appliances and we greatlyappreciate your expertise. Thank you. Thank you.