Using a gas stove burner without its cap: bad idea? (And if so, why?)
December 22, 2020 2:35 PM   Subscribe

Kenji Lopez-Alt shows how, just by taking off the cap, a gas stove burner can be temporarily used as a wok burner. Is this a bad idea, and if so, what makes it bad?

I've always been annoyed at how my gas stove burners - like almost all burners out there - send out a flame sideways, heating the sides of the pot and leaving the center of the pot cold. So Kenji's method seems promising. What's the catch? Would especially value opinions from folks with some idea of how the diffuser cap works and why we can't simply have the flame go to the center of the pot.
posted by splitpeasoup to Home & Garden (16 answers total) 5 users marked this as a favorite
The post itself mentions "don't drop anything down the gas line and have a kitchen fire extinguisher handy," so presumably that could be a problem. Also having a column of flame several inches high seems potentially hazardous, but only because it's unexpected--definitely a thing you would want to warn anyone in the kitchen with you about.
posted by JDHarper at 2:50 PM on December 22, 2020

I'm a very risk-tolerant person.

I wouldn't do this, as I'm almost entirely certain DIY modifications to my household appliances would effectively void my homeowner's insurance. Even if the modification itself didn't cause a fire, any investigation to a fire that noticed my stove was not "stock" would almost definitely be used against me and result in claim denial.

Like many things in life, it doesn't matter so much if you are right or wrong, so much as you are able to defend in court against a very well-funded adversary that you are right or wrong.
posted by saeculorum at 3:51 PM on December 22, 2020 [3 favorites]

Mostly just because it's potentially a fire hazard, and as JDHarper said, there's an increased risk of dropping something in the gas line. I've taken the diffuser cap off before when cleaning a stove, and the flame you get can be well beyond what you'd want to safely have in a residential kitchen. Stoves in homes are often below cabinets or microwave ovens, and without the diffuser or a pot on top, the flame can easily get to one or two feet high. If you're going to try it, please keep a fire extinguisher on hand and be really careful. Commercial ranges usually have way more clearance, and are set up with nothing flammable above them. Not so for your typical kitchen.
posted by mrgoat at 4:00 PM on December 22, 2020 [10 favorites]

Best answer: For clarification, this is a temporary change in how the stove is used and not a "modification" per se. Of course, if the house burned down while the burner cover was off and that came up in the investigation, then you'd have insurance issues.

My guess is that it's mostly there to keep grease and solids from getting into the gas nozzles and interfering with the combustion.

On the downside, it's more concentrated heat than the stove manufacturer would necessarily have tested for, it's more heat in one spot than building codes (e.g. cabinet height and whether range hood was necessary) would have accounted for.

IANAL but I was surprised when I saw Kenji suggest this. Seems unnecessarily risky for him, just from a liability standpoint, because even if it's okay but someone screws up while doing it, like dropping a wokful of oil onto that flame, he could be in for some shit. My guess is that it will not be in his upcoming wok cookbook because the publisher would have lawyers that would get leery over it.

Personally I'd stick to normal diffuse heat indoors, or use an outdoor wok burner.
posted by supercres at 4:04 PM on December 22, 2020 [3 favorites]

Best answer: This is removing one safety feature of the stove, namely a point at which oxidizer is not available, preventing the flame back burning towards the fuel source.

If the flame were go go out, and then be re-ignited by a heat source, you've created a strong fuel-air region at the center that could explode. The advantage of the diffuser is that a flame can't readily cross the diffuser holes, or does so in a slow manner against the rushing gas.
posted by nickggully at 5:11 PM on December 22, 2020 [8 favorites]

Don't do this. The burner is designed to have the flame ignite at the edge of the burner. The flame burning in the center could heat the casting where it isn't designed to be heated and damage either the casting, the gas tubes, or some associated item like the igniter. The joint between the burner casting and gas tubes is an especially problematic area that could be negatively effected.

And supercres is right that the flame edges are way closer to your overhead hood/cabinet than what any of the equipment was designed for. No consumer grade range has jets facing up for just this reason. (in contrast to commercial equipment which is all up facing jets.)

Also in case it isn't clear no additional heat will be generated doing this. It'll be concetrated in the center but the same BTUs will be given off.
posted by Mitheral at 5:16 PM on December 22, 2020 [3 favorites]

heating the sides of the pot and leaving the center of the pot cold.

I'm not so sure this is true or at least not significantly so. Steel is a pretty good conductor of heat so that it will flow from the edges toward the center. You can help this out a bit by sliding the wok around the burner to get more heat in the middle.

Someone with an infrared thermometer might be able to quantify the temperature difference between the edges and the center of the wok.
posted by JackFlash at 5:41 PM on December 22, 2020 [1 favorite]

Former appliance repair professional here, who has worked on countless domestic gas ovens.

There's really no need to do this if you have a gas range, no matter the shape of the flame. You already have an open flame burner, that's what woks like. If it's not direct enough for you, maybe try a small burner turned up high. But really, just pretend you don't have a problem, and you'll find you don't actually have a problem.

If you want to customize it for a curved wok, swap the cast-iron piece over your burner (which you rest the pans upon) with a level surface, for one with a curved surface specifically to hold curved woks. Your oven manufacturer probably sells such an optional cast-iron piece for your burners. Or you get get an over the counter version from a cooking-tools store and put it in place.

What the cap does is to distribute the heat evenly around the shape of the burner, keep food from falling into the aperture or air-mixture space, and sometimes with some self-re-lighting ranges the cap will form part of the grounding path for your re-lighting spark plug thingy. In other words, it's possible that you may need the cap in place for the re-lighting feature to work, and if it's not in place it may go *spark spark spark spark* forever trying to help you cause it thinks there's no flame present, or fail to relight the flame if it's gone out, or something like that.

There is some danger from stuff falling down into your aperture/mixture space, yes. I don't think there's much danger of your aluminum pieces warping from heat being in the wrong place. Anyway- with a gas range, you already have the thing you want for wok cooking! Even flat bottomed woks don't behave the same way on a radiant-heat stove, much less an induction stove or a resistive element stove. You are good to go.
posted by panhopticon at 5:46 PM on December 22, 2020 [18 favorites]

If your stove is like mine was, it's not going to damage the stove, but it seems generally useless to me. Unless you are setting a pan directly on the burner cap, the heat at the center should be quite sufficient just due to the way the air mixes. You can't see flame in the center if the gas is on high enough, but it's still plenty hot in that area.
posted by wierdo at 7:55 PM on December 22, 2020

Best answer: I tried this. It was scary and despite my very high hopes, the bottom of my wok didn't seem hotter. If anything, the flames just went higher up the sides. I'm risk-tolerant in the kitchen (I come from turkey frying people!), but it made me super worried about burning my hands, and my stir fry performance was not improved.
posted by mostlymartha at 9:54 PM on December 22, 2020 [1 favorite]

the motivation here is not to center the flame more but to get a flame that can leap somewhat over the rim and heat the oil vapors, burning them to create “wok hei”, the magic that distinguishes home cooked chinese from restaurant chinese. this does sound dangerous though, and id go with a propane wok burner outdoors before i’d try this
posted by dis_integration at 10:37 PM on December 22, 2020

Yeah tall flame that comes up the sides is a feature not a bug. I’d definitely go for the blowtorch trick before trying this if you can’t do outdoor propane burner.
posted by supercres at 11:00 PM on December 22, 2020 [1 favorite]

For clarification, this is a temporary change in how the stove is used and not a "modification" per se. Of course, if the house burned down while the burner cover was off and that came up in the investigation, then you'd have insurance issues.

If you set your upper cabinets on fire and just put the piece back afterwards, the insurance adjuster is going to roll his or her eyes as your claim get denied.
posted by sideshow at 11:35 PM on December 22, 2020 [1 favorite]

I just pulled my cap off a medium burner on my stove and lit it. It was a bit fiddly to get going at first. I found staring low and then with a pot on top it worked fine. I don't see how any stove components would get damaged. I do see how this would cause wear on the inner part of the spreader ring, which I expect would still last decades, and get inner components dirty in ways that would be a hassle to clean. It was the same amount of heat, just focused in a single column.

As long as your safety valve is properly working and you don't smell gas and aren't actively lighting things on fire I think this is as save as waving a handheld torch around the kitchen. Which is to say, slightly more dangerous than not being near things that are hot or on fire.
posted by zenon at 11:19 AM on December 23, 2020

I may have been too hypothetical re: damage to burners. I've seen it plenty where dirty or misaligned caps have led to bases being damaged (IE:warped) or less often the gasket between the tubes and the base being eroded away. Admittedly it generally happened with specific manufacturers rather than being a universal problem so there is an associated design issue.

If you consult your owners manual for your range it will likely contain instructions (at least all the half dozen I pulled up with a quick google search did) along the lines of

"Burner cap: Always keep the burner cap in place when using a surface burner."
"Caution: ... use the cooktop with all burner caps properly installed"
"Do not operate the range if the range or any part of the range is damaged, malfunctioning, or missing parts."
"Before igniting the burners, make sure all burner caps are properly in place and all burners are level."
"CAUTION Do not operate the burners without all parts in place."

$Deity knows I don't always use devices as the manufacturer intended but they are aware of and warn about risks from not using the burners as designed.
posted by Mitheral at 1:29 PM on December 23, 2020

This seems along the same lines as advice from chefs to disable the interlock on your oven's self-clean feature to bake pizza at higher temps. It might work out okay (and probably will for most folks), but you really don't want to find out if it doesn't.
posted by Aleyn at 2:57 PM on December 23, 2020

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