A commercial fryer smokes for one of a few reasons: the oil is worn out and smoking at normal frying temperature, the oil is hotter than the set point because the thermostat is off, the oil level is too low, crumbs and carbon are burning in the bottom of the pot, or the hood is not pulling the vapor away. If the oil is smoking heavily and still getting hotter, turn the fryer off first and work out the cause once it is cool.
Shop the equipment in this article: gas fryers, commercial deep fryers and fryer accessories. Freight is included on every order.
The steps below apply to gas floor fryers such as the Cookline CF40-LP fryer and to countertop electric fryers. Wisps of steam when wet food goes in are normal. Steady blue-gray smoke from the oil surface is not.
Safety first
- If the oil is smoking and the temperature keeps rising, turn the fryer off and keep everyone back.
- Never pour water on hot oil or an oil fire. Use the kitchen’s fire suppression system or a Class K extinguisher and follow your fire plan.
- Do not try to move or drain a fryer full of hot oil to “cool it down.”
1. The oil is broken down
Fresh oil can sit at frying temperature without smoking. As oil is used, food particles, water and salt break it down, and common practice in kitchens is that old oil starts smoking at temperatures where fresh oil did not. Signs that point to the oil itself: dark color, a sharp or burnt smell, foam that does not settle, and food that browns too fast.
The fix is filtering daily and changing the oil when it is spent. Our guide on how to filter fryer oil and when to change it covers the routine, and why fryer oil foams explains the related signs.
2. The oil is hotter than the setting
If the oil smokes even when it is fresh, check the real temperature with a separate probe thermometer. Set the dial, let the fryer cycle, and compare. A thermostat that reads low lets the burners or elements keep firing past the set point.
Know your fryer’s range before you judge it. These figures come from our product pages:
| Fryer | Oil | Heat | Thermostat |
|---|---|---|---|
| Cookline CF40-LP | 40 lb | 90,000 BTU, 3 tube burners | Millivolt thermostat, no electricity needed |
| Westlake GF90-P | 40 lb | 90,000 BTU, 3 tube burners | 200 to 400 F |
| Cookline DF15-1-120 countertop | 15 lb | 1,750 W element, 120 V | 122 to 374 F, high limit safety cutoff at 446 F |
The high limit is a safety cutoff, not a working temperature. If a fryer keeps reaching its high limit and shutting off, the thermostat or its sensor needs service. A gas fryer whose oil overshoots the set point needs a qualified gas technician to check the thermostat and calibration.
3. The oil level is too low
Oil burns off and gets carried out on food all day. When the level drops below the fill line, the hot tank walls above the oil and the heating tubes or elements can scorch the thin film of oil on them and smoke. Top off to the fill line marked in the pot, and check the level before every rush. A 40 lb fryer is built to run with 40 lb of oil, not 30.
4. Crumbs and carbon are burning
Breading and crumbs that drop to the bottom of the pot keep cooking. Fryers with a cold zone, such as the CF40-LP and the Westlake models with a deep cold zone, give those crumbs a cooler place to settle, but the zone still has to be cleared. Skim crumbs often during service, drain and filter at the end of the day, and clean the pot. Carbon that builds up on the tube walls or elements smokes every time the fryer heats.
A full boil-out removes the carbon that skimming misses. See how to boil out a commercial deep fryer, and rinse and dry the pot completely before new oil goes in, since water left in the pot makes the oil spatter and foam.
5. It is a brand new fryer
A new fryer can give off smoke and an odor the first few times it heats, as factory oils and coatings burn off. Common practice is to clean the pot as the manual directs, do a boil-out if the manual calls for one, and run the first heat-up with the hood on. If the smoke continues after the first few heat cycles, look at the causes above.
6. The smoke is coming from the burners, not the oil
On a gas fryer, smoke or soot from under the pot rather than from the oil surface points to combustion: a lazy yellow flame, blocked burner ports or a flue that is not drawing. Our product pages state that fryers must go under a hood, and a hood that is off or clogged with grease lets vapor and smoke hang over the line. Turn the hood on before the fryer, keep the filters clean, and have the burners and gas pressure checked by a licensed gas technician. The signs are similar to the ones in a gas range burner with a yellow flame.
What to buy
- A probe thermometer to check the oil against the dial, plus filter supplies from our fryer accessories.
- A fryer with a cold zone and a thermostat range that fits your menu, from our gas fryers.
- A second fryer if one pot is running all day without time to filter.
- For gas kitchens on propane, the Cookline CF40-LP; for natural gas, ask about the CF40-NG as listed on the CF40-LP page.
Freight with liftgate delivery to the 48 contiguous states is included in the price. The CF40-LP page lists a 1 year parts and labor warranty, and gas connections should always be made by a licensed installer.