Remember the days when putting a refrigerator in Shabbos mode meant taping up a spring-loaded switch or unscrewing a light bulb?

While some of those ancient appliances still exist, many of today’s ovens, refrigerators, and other kitchen gadgets feature advanced technology like touch controls, LED screens, and digital humidity gauges, all of which can make cooking easier but also makes setting your oven for Shabbos and Yom Tov harder.

Enter Jonah Ottensoser, a leading authority on kosher ovens and appliances for the STAR-K organization of Baltimore, the only kosher certifying agency to partner with manufacturers to create “Sabbath mode” appliances. Mr. Ottensoser works with companies like GE, Whirlpool, Viking, Sub-Zero, and Frigidaire to help them build products that Jewish consumers can use (to a limited degree) on Yom Tov and Shabbos. Today, thousands of appliances are certified with Sabbath Mode functions, from refrigerators to cooktops to ranges to wall ovens to wine coolers.

It’s a fourth career for Mr. Ottensoser, who has started off as an aerospace engineer for the U.S. government and then later worked as a data analyst for defense contractor Wylie Labs. He has also taught mathematics at Towson University, Stevenson University, and Howard Community College, all in Maryland. Mr. Ottensoser earned a bachelor’s degree in mechanical engineering at City College of New York and a master’s in the same subject from Catholic University in Washington, D.C.

Mr. Ottensoser, who’s been with the STAR-K for 20 years, has helped 31 companies design Sabbath mode appliances for thousands of products. He personally visits the manufacturers between five and ten times per year, crisscrossing the country from Benton Harbor, Michigan to Louisville, Kentucky to Milwaukee, Wisconsin, and Los Angeles, California.

“I was once asked by LG to go to South Korea, but I declined,” recalls Mr. Ottensoser. “I didn’t want to travel 32 hours or be in a country where I know nothing about the language. The engineer tried to convince me, saying, ‘I’ll treat you very well and take you to the best crab houses in the city!’ He obviously knew nothing about kosher.”

‘Just Do It’

There’s a pressing need for “Sabbath Mode” appliances these days because manufacturers keep on adding fancy bells and whistles to their products. When he asks them why, he says they answer “because we can!” But all that technology can complicate Shabbos and Yom Tov observance.

“Electronics do funny things and sometimes the manufacturers, themselves can’t figure things out,” says Mr. Ottensoser, 73, who lives in Baltimore. “And it’s only going to get worse.”

For example, he says, there are refrigerators on the market built with internal cameras that can show you exactly what’s inside. That’s great when you’re at the grocery and you aren’t sure what you have at home, but problematic on Shabbos. Other high-end refrigerators are installed with proximity sensors that set off lights when you approach them. That’s a real advantage if you want a drink at 2 a.m., but again, problematic for the Sabbath-observant Jew.

“The engineers [at the companies], within a short time, understand what we’re after,” says Mr. Ottensoser. “Sometimes, in fact, they will point out something that I may have missed, for example, if there isn’t a delay in the oven where there should have been one. I’ve never had a problem with them to sneak something by. They always are respectful and concerned that they meet our requirements.”

When I met Mr. Ottensoser at STAR-K’s Baltimore, Maryland headquarters recently he was getting ready to head out to a GE plant in Louisville, Kentucky, to test a new wall oven.

“Companies, in general, put out good products, but sometimes they get too detailed — you have to push too many buttons,” explains Mr. Ottensoser. “If I were a housewife, I would want to turn the flame on and get the stuff cooked — not push the menu and choose. We just have to make sure that it’s easy to use and that nothing funny happens — like lights going on when they shouldn’t.”

Part of his job is to explain Jewish legal concepts like “gramma” to the engineers so they’ll understand the goal of the Sabbath Mode technology. But some ideas translate better than others.

“Years ago, when we were at GE, a funny thing happened,” recalls Mr. Ottensoser. “If you [follow the STAR-K position, and] change the temperature in an oven on Yom Tov in Sabbath Mode, there is a random 15-30-second-long delay before the oven actually starts to heat. This is gramma,” he explains. “This was hard for the outsourced engineering team contracted by GE in Japan to fathom. GE kept telling the engineers, ‘We want to put a delay there,’ and the engineers kept saying, ‘Why do you want a delay? Have it happen right away!’ They could never understand why there was a delay and that it was for religious purposes, so GE finally told them, ‘Just do it and don’t ask questions!’”

From Navy Pilots to Oven Pilots                                       

Jonah Ottensoser grew up in Washington Heights (where his family had a pilot-lit stove). After he graduated from City College, he got his first job as a civilian government employee for the U.S. Navy in Bethesda, Maryland. He conducted wind tunnel testing to measure the lift and drag forces on aircraft, and later tested flying qualities in aircraft. When he first started working there, he was the only frum person on staff.

“In general, I found my coworkers to be very respectful of my beliefs,” he says. “The key was always to be consistent and straight. If I can’t work on Shabbos, it’s not that I sometimes can — I can’t. If I only eat kosher, I don’t make an exception for a good piece of cake.”

When Mr. Ottensoser’s workplace relocated to the Naval Air Station in Patuxent River, about 90 miles away from home, he took an “early-out” retirement after 31 years. Around that same time, Mr. Ottensoser met up with a neighbor, STAR-K President Avrom Pollak.

Dr. Pollak told him that STAR-K was running into issues with a new invention, automatic timers installed in ovens that automatically shut them down after 12 hours. Now a standard feature in most ovens, the STAR-K was looking for someone to provide a solution for making these ovens available for use throughout the Sabbath and Yom Tov.

“He asked me if I was interested in getting involved with it, and I told him, ‘sure.’ It was perfect timing, min haShamayim.”

Other technological issues soon arose, including digital displays, tones, and icons. Soon enough, Mr. Ottensoser had plenty of work. He says STAR-K benefits greatly from the guidance and leadership of Rabbi Moshe Heinemann, who appreciates the intersection of technology and Shabbos observance. “Many rabbanim will say they don’t understand this type of thing, but the Rav really understands what is going on and can apply the halachah, even though it’s at times controversial.”

Rabbi Heinemann’s ruling that Sabbath Mode appliances can be used throughout Yom Tov has been criticized by rabbis both in America and Israel. There are many poskim who do not rely on Rabbi Heinemann’s ruling.

STAR-K has also run into a problem with people who are not fully acquainted with the halachos of Shabbos who believe they can use a “Sabbath Mode” oven to cook on Shabbos. Part of the problem has been the term “Sabbath Mode,” which could be read to imply permissible use on Shabbos. Mr. Ottensoser explains that manufacturers, not STAR-K, invented the term. “Their reason for this choice of name was simply because what else would they have called it? ‘No Work Mode?’ ‘Jewish Mode?’ I don’t think they would want to put that on their oven.”

Because there is a sizeable population that uses Sabbath Mode products, STAR-K further clarified on its website that “Sabbath Mode” does not mean that melachos can be transgressed on Shabbos.

“There are still halachos that govern how you deal with these appliances on the Sabbath and Yom Tov,” says Mr. Ottensoser. “We clearly list on our website the halachos for each of the appliances we certify. Unfortunately, many people don’t read this information.”

Mr. Ottensoser explains by way of analogy. “Just like every car has gas and brake pedals and a steering wheel, with varying controls that differentiate them, the same is true of major appliances. Sometimes, there are unique features or an absence of them if they are Sabbath Mode models.”

STAR-K certifies both “Sabbath Mode” and “Sabbath Compliant” ovens. What’s the difference? Whereas the Sabbath Mode appliance is designed from the start to incorporate all its features possible under the halachah, the Sabbath Compliant appliance is designed without the kosher consumer in mind, though is usable on Shabbos and Yom Tov with some Hot Sh’eilos

Several thousand calls are received annually by the STAR-K Hotline regarding the Sabbath Mode appliances it certifies. On Erev Yom Tov, especially, the phones ring off the hook. This year, between Purim and Pesach alone, 10,723 calls were fielded by the Hotline from all over the world. A good percentage of them were appliance-specific. All sh’eilos are answered according to the rulings of Rabbi Heinemann.

Some of these sh’eilos include:

Q: Does the new steam clean (as opposed to the more common self-clean) method of cleaning the oven kasher the oven?

Q: For a double wall oven, can one use one oven for meat and the other for dairy?

Q: Does using an induction cooktop avoid bishul akum?

Q: Does steam bake in an oven create kashrus issues?

Q: If a dishwasher is very quiet can it be set on a timer to be used on Yom Tov?

Q: Can food be put into an operating warming drawer on Shabbos?

In some cases, fielding a call from a consumer who says that their Sabbath Mode appliance is not working properly may simply mean the consumer is not reading the instructions properly. Other times, it’s a tip off for Mr. Ottensoser to carefully review the owner’s manual together with a company’s engineering team to look for discrepancies.

“A good part of the time, the manual is written by engineers, so they fill in the steps,” explains Mr. Ottensoser. “One company had the steps for the Sabbath Mode, but it didn’t work because at the end of those steps you need to push ‘Start.’ The engineer, of course, knows you need to push ‘Start’ after every process, but the consumer doesn’t. So, I go and try to act like some housewife, and read it literally because that is what she is going to be doing, and very often, it’s wrong, misleading, or omits important steps, which is a big problem.”

Sometimes, Mr. Ottensoser admits, there are actual issues in appliances, like unexpected “sneak circuits” that lead to unexpected and undesirable outcomes. “We have one side-by-side refrigerator where when you open one door, no light goes on; when you open the other door, no light goes on; but if you open both doors at one time, the lights will go on. It happens really in all big electrical type systems, so they had a mistake there. We also have an oven now, that when you are in Sabbath Mode and you open the door, the time gets displayed; when you close the door, the time goes off. Another problem.”

Mr. Ottensoser once got a call on Erev Shabbos, about 20 minutes before lichtbentshen , from a man in Lakewood who had just moved into his house and forgot to inspect his refrigerator beforehand; he couldn’t get the refrigerator light to turn off.

“I couldn’t think fast enough, so what he ended up doing was storing his food outside in the cold garage,” says Mr. Ottensoser. “It turned out he had a magnetic switch. A lot of companies are installing a magnetic switch like this fellow has, with a magnet in the door and a reed switch hidden in the frame. It looks neater than the button that goes in and out. When the magnet approaches the door, it pulls the switch apart so that it is open and the light goes off. When you pull the door away, the switch falls back down and the light goes on.”

Mr. Ottensoser admits that a lot of responsibility comes with coaching consumers and engineering teams alike to ensure all the halachos are being followed.

“I guess I should train other people because I’m not getting any younger, although I like to think so,” he says. “There has to be some transmission. It’s really not that hard, you just have to be technically aware of what is going on. The joke is that we’re using software to make modern appliances like they were 35 years ago.”