Commercial Combi Oven: Descaling — Causes & Fixes

1. Remove all food and pans. Let the oven cool to the temperature the control requires before adding tablets — the display shows a cool-down (red interior) if it's too hot; wait for it.
2. Open the drain / remove the drain cover if your model directs it, and place the required number of cleaner tabs where the screen indicates (e.g., into the condensate box through the drain opening), or spray the interior with the approved spray cleaner. Add rinse-aid to its container if your model uses it.
3. Confirm the water supply is on (press the water-on icon if prompted) and select the cleaning level that matches the soil (rinse/light for light soil, normal/heavy for baked-on grease).
4. Press start and let the full cycle run — do not open the door mid-cycle; caustic cleaner is circulating.
5. When it finishes, confirm the rinse completed, wipe out any residue, and leave the door slightly ajar to air the chamber before next use.
6. Never use unapproved oven cleaners or abrasive pads inside a combi, and always wear gloves and eye protection when handling the tabs/spray.

· Tools: Manufacturer-approved cleaner tabs or spray cleaner (e.g., CombiClean tabs, Rational cleaner tabs), Manufacturer-approved rinse-aid (if your model uses it), Heat-resistant gloves, Eye protection (cleaner chemicals are caustic) · Source: Alto-Shaam Combitherm CombiTouch Operation Manual (cleaning levels, add-tabs-through-drain, water-on confirm, door-ajar); Blodgett BLCT/BCT CombiWash (OEM detergent/rinse-aid, cool below 80°C, select mode, start) — Parts Town

1. Empty the oven completely — no pans, no product. Descaler is corrosive and must never touch food-contact use during the cycle.
2. Confirm the descaler container is full with the correct, undiluted approved descaler (never substitute another acid).
3. Open the descale/delime program from the control menu (e.g., Blodgett: Gear icon > Super User > Delime Program > Delime; Rational SelfCookingCenter: Function > service menu > Descaling) and confirm the oven is empty when prompted.
4. Let the automatic cycle run to completion; press stop only if the manual tells you to.
5. Run the flush/rinse step afterward (e.g., Blodgett Delime Flush) so no descaler remains in the boiler before cooking.
6. If the display still shows weak steam or a descale prompt after the cycle, or the generator is heavily scaled, stop and have a technician descale the boiler manually — do not open the boiler yourself.
7. Fix the root cause: if scaling recurs quickly, your water needs treatment (filtration, softening, or RO).

· Tools: Only the manufacturer-approved descaler (e.g., Blodgett deliming agent, Convotherm DISSOLVE descaler), Heat-resistant gloves and eye protection · Source: Blodgett BLCT/BCT Delime Program + Delime Flush (Parts Town Blodgett wash & PM guide); Convotherm DISSOLVE descaler method; Rational SelfCookingCenter descaling menu (TechTown Rational descale KB)

1. Let the oven fully cool and make sure it's off. Open the door.
2. Pull out the old gasket and remove every trace of the old dart/material from the channel; wipe the channel clean.
3. Paint the channel (and the gasket dart) with a mild soapy solution so the dart slides in.
4. Seat the gasket's dart into the channel at the corners first — top corners, then bottom corners — pressing the dart fully home.
5. Work the loose gasket between each corner into the channel with a blunt tool, doing the middle sections last so the length distributes evenly and there are no gaps.
6. Close the door and check for an even seal all the way around; if the door still won't pull tight or sits crooked, the latch/hinge needs a technician — don't force it.

· Tools: Correct replacement gasket for your model, Blunt plastic tool / seam tool, Mild soapy solution, Clean cloth · Source: Convotherm/Cleveland door-seal replacement method (remove all old gasket, soapy channel, seat dart corners-first then middle) — techtown Convotherm door-seal discussion; Parts Town Cleveland/Convotherm troubleshooting

1. Turn the oven off and let it cool.
2. Clean the fan grille at the bottom of the unit and the air intake at the base so cooling air flows freely (a blocked intake causes high-temperature faults).
3. On models with a pull-out control/air filter, pull the filter, wash it with soap and water, dry it, and reinstall it.
4. Wipe the interior chamber, door, and gasket with warm soapy water and a soft cloth; for discoloration from poor water quality, apply the approved cleaner (e.g., ConvoCare) to a COLD chamber, wait ~10 minutes, wipe off, then run a normal clean cycle.
5. Clear the chamber drain and screen of grease and debris so water drains freely.
6. Do not use abrasive pads, wire brushes, or unapproved chemicals on the interior or gasket.

· Tools: Mild dish soap and warm water, Soft cloth or sponge (no abrasives), Approved cleaner for behind the fan guard (if applicable) · Source: Convotherm E02 (clean fan grille/air intake) and ConvoCare discoloration procedure — Parts Town; Blodgett BLCT/BCT weekly PM (pull and wash control filter) — Parts Town

1. Shut off the water supply to the filter head and relieve pressure per the filter maker's instructions.
2. Remove the spent cartridge (catch any water) and install the new cartridge, noting the install date.
3. Turn the water back on, check for leaks, and flush the new cartridge per its instructions before returning the oven to service.
4. Reset the oven's filter prompt/counter if your model tracks it, and log the change so the 3–6 month schedule stays on track.
5. If the oven kept steaming poorly with a fresh filter, the incoming water may be out of spec — have water quality tested and treated.

· Tools: Correct replacement water-filter cartridge, Bucket / towel for residual water · Source: Convotherm 4 error E10 'replace the filter cartridge' (Parts Town); water-filter replacement interval and owner water-quality responsibility (Alto-Shaam Combitherm CombiTouch Operation Manual; Rational water-filtration guidance)