Thetford C220 waste tank blade opener knob - blue, original part 200970 for the cassette toilet tank

The blade opener knob is a small part, but without it the cassette of a Thetford C220 toilet does not work properly. It sits on the waste-holding tank and is part of the mechanism that opens and closes the blade between the toilet bowl and the tank. In the Thetford parts catalogue it is called blade opener, number 200970 in colour 85, which is blue. When the knob cracks, wears out or gets lost, the blade no longer opens or closes properly and odours start to reach the bathroom. Instead of buying a whole new tank, you replace just this part. The photos show the blue knob with a black O-ring and a white plastic part that works together with the knob in the tank.

Key features

• original Thetford spare part, number 200970, colour 85 (blue)
• for the waste-holding tank of C220 series cassette toilets
• fits the standard tank and the outside vent version
• blue knob with black O-ring
• white plastic part included as shown in the photo
• made of plastic

When to replace the knob

• The knob is cracked, broken or lost.
• The blade does not open fully or does not close.
• The knob turns loosely and does not move the blade.
• Liquid leaks from under the knob because the O-ring is worn or damaged.

How to check that it fits

The knob fits the waste-holding tanks of Thetford C220 series cassette toilets. You find the toilet type on the rating plate, and you can recognise a C220 tank by the blue knob on top, the wheels and the transport handle. The same part is fitted in the standard tank and in the outside vent version, so you do not need to check which cassette version you have. Compare your old part with the one in the photos before you start removing it.

Replacement step by step

• Empty and rinse the tank thoroughly before you start.
• Close the blade and place the tank on a stable surface.
• Remove the old knob together with the parts that work with it and note how they sit.
• Clean any deposits from the knob seat.
• Lubricate the O-ring of the new knob with a seal care product.
• Fit the new parts in the same position as the old ones and check that the blade opens and closes fully.
• Finally pour some water into the tank and check that nothing leaks.

Caring for the blade mechanism

• Care for the seals and O-rings regularly with a spray made for cassette toilets, so the blade and the knob move easily.
• Do not clean the tank with household cleaners, as they may permanently damage the seals and the plastic.
• Use toilet paper that dissolves quickly, so residues do not block the mechanism.
• If the blade and its seal are worn too, replace them with the Fresh-Up Set C220.

Which toilets

• Thetford C223-S
• Thetford C223-CS
• Thetford C224-CW
• Thetford C222-SWE
• other C220 series cassette toilets with the 18 l tank

Matching Thetford tanks, toilets and parts

• Thetford C220 waste-holding tank 18 l - complete tank this knob works in
• Thetford C220 tank, outside vent version - complete tank in the outside vent version
• Thetford C220 blade handle - grey handle on the toilet you use to open the blade
• Thetford Fresh-Up Set C220 - set with a new blade and seals for the tank
• Thetford C220 float arm - part of the level indicator in the tank
• Thetford C220 cap with measuring cup - replacement cap for the pour-out spout
• Thetford C223-S cassette toilet - C220 series toilet with electric flush
• Thetford C223-CS cassette toilet - C220 series toilet
• Thetford C224-CW cassette toilet - C220 series toilet with its own water tank
• Thetford Seal Lubricant - spray for seal and O-ring care

Technical data

Manufacturer

Thetford B.V., Nijverheidsweg 29, 4879 AP Etten-Leur, the Netherlands.