To boil out a commercial deep fryer, drain and filter out the oil, fill the fry pot with water and a fryer boil-out cleaner to the oil line, bring it to a gentle simmer, scrub the walls and tubes, then drain, rinse, neutralize if the cleaner calls for it, and dry the pot completely before adding fresh oil. Busy kitchens usually do this every one to four weeks.
Shop the equipment in this article: grease traps, Cookline CF40LP fryer and commercial deep fryers. Freight is included on every order.
Daily filtering removes crumbs. A boil-out removes the hard, varnish-like carbon that builds on the pot walls and heating tubes over weeks of service. That buildup shortens oil life, slows temperature recovery and darkens food.
Before you start
Read the manual for your fryer. Some manufacturers set a maximum boil-out temperature, list approved cleaners or describe a specific procedure, and following it protects the warranty. Use only a cleaner made for fryer boil-outs and follow its label for the amount, time and rinse.
Wear heat-resistant gloves, an apron and eye protection. Clear the area around the fryer, and never leave a fryer unattended while the solution is heating. The solution can foam up quickly.
What you need:
- Fryer boil-out cleaner.
- A long-handled fryer brush and a scraper.
- A drain pan or oil caddy rated for hot liquid.
- A rinse product or mild acid rinse if the cleaner label calls for one.
- Clean towels.
Step 1: Drain the oil
Turn the fryer off and let the oil cool to a safe handling temperature. Drain it through the drain valve into an approved container. Do not pour oil into a sink or floor drain, because grease clogs plumbing and grease traps. Remove the baskets and any crumb screen.
Step 2: Scrape out debris
With the pot empty, scrape crumbs and sludge from the bottom and from around the tubes or elements. On floor fryers with a cold zone, such as the Cookline CF50-NG, the cold zone under the tubes is where most of the sediment collects, so clean it out thoroughly. Then close the drain valve.
Step 3: Fill with water and cleaner
Fill the pot with water to the oil fill line, not above it. Add the boil-out cleaner in the amount on its label and stir gently.
Step 4: Bring it to a simmer
Turn the fryer on and bring the solution to a simmer or low boil, well below frying temperature unless your manual says otherwise. Watch it the whole time. Simmer for the time on the cleaner label, often 15 to 20 minutes.
On gas fryers the burners and pilot stay in normal operation during the boil. The Cookline CF40LP fryer, for example, runs on a millivolt thermostat with no electrical connection, so the boil-out uses the same thermostat dial you fry with.
Step 5: Scrub
Turn the fryer off. With gloves on, scrub the walls, corners and tubes with the long-handled brush. The band just above the normal oil line is usually where carbon is thickest.
Step 6: Drain, rinse and neutralize
Let the solution cool enough to handle, then drain it into a safe container. Refill with clean water and drain again. Many boil-out cleaners are strongly alkaline and need a neutralizing rinse; follow the label exactly, then rinse again with clean water.
Step 7: Dry completely
Wipe the pot with clean towels and leave the drain valve open so it air dries. Any water left in the pot will spatter violently when hot oil goes in. Close the valve before refilling with fresh oil.
Clean the baskets and accessories
Soak fry baskets in warm water and degreaser, scrub, rinse and dry. Straighten bent hooks so baskets hang securely on the hanger. The CF40-LP comes with two nickel-plated baskets and a basket hanger plate, and those hangers collect oil and crumbs too.
Countertop electric fryers are different
Many countertop electric fryers are not boiled out in place. The DF15-2-120 dual tank countertop fryer, for example, has removable fry pots and a removable electric box, with a wire mesh net that catches crumbs and protects the heater. On units like this, the manual’s cleaning method applies, and the heating element and controls must stay dry. If your manual does not describe a boil-out, do not improvise one.
How often to boil out
- High-volume fryers doing breaded chicken or fish: often weekly.
- Fryers doing mostly fries: often every two to four weeks.
- Any fryer whose oil darkens quickly even with daily filtering: probably now.
These are common practice figures, not rules. Your manual and your oil tell you more than a calendar.
Mistakes to avoid
- Filling above the oil line, which lets solution foam over.
- Leaving the fryer unattended while the solution heats.
- Skipping the neutralizing rinse when the cleaner calls for one.
- Refilling with oil while water is still in the pot.
- Using a cleaner not made for fryers.
When cleaning will not help
If the fry pot is pitted, cracked or leaking, cleaning will not fix it. Compare replacements in our commercial deep fryers and gas fryers categories. Freight to the 48 contiguous states is included in the price, and fryers, as powered equipment, have a 7-day return window.
Frequently asked questions
How long should a fryer boil-out take?
Most of the time is cooling and drying. The simmer itself is usually 15 to 20 minutes, or the time on the cleaner label.
Can I use dish soap to boil out a fryer?
Use a cleaner made for fryer boil-outs. Dish soap foams heavily and is hard to rinse out of a fry pot.
Why do I need to dry the pot so carefully?
Water left in the pot turns to steam the moment hot oil touches it and throws oil out of the fryer. Leave the drain valve open and let it air dry.
Does a boil-out replace daily filtering?
No. Filter daily to remove crumbs, and boil out periodically to remove carbon.