Rational CPC201 repairs

In this instance, the steam boiler has had power fed while water level was low, and i have removed the whole boiler to give it a manual clean and replace the coupling between the boiler and cooking cabinet, as well as all four elements.

This applies to all models, but i am showing the job on the CPC201. It requires a 10mm socket and a pair of pliers, and will take around 2-3 hours to complete.

The boiler can be seen here on the bench with the four elements removed:


And this was the contents of scale build up. The scale is somewhat normal, but this alone will not cause element failure:


Here is a failed element, caused from running dry, with such failure the water leaks out and can damage the lower motor in extreme cases:


And here is a new element for comparison:


The boiler is held in place by 2 or 3 10mm nuts, depending on the model, as well as 2 hose clamps on the coupler at the top. The pump out motor is held to a bracket with two 10mm bolts in the back ( front on SCC ) and the hose clamps are spring steel types. The water level sensor is held in place by 4 10mm nuts, and may need to be pryed off gently with a flat blade screwdriver. The elements are held by 4 10mm nuts each, and in the case of the CM and CPC use the same rubber gasket as the level sensor. A new gasket is supplied with the element, i rarely replace the sensor gasket. The coupler is a short rubber hose and should be replaced as it deteriorates over time and leaks water down the back of the boiler. The pump motor should be cleaned out and checked for function after after reinstallation, but they rarely seem to fail.

After stripping the boiler a often use a screwdriver and hammer to remove scale, taking care not to damage the water inlet or the probe pocket.


Once cleaned reasonably well, i generally fit four brand new elements, however if any are obviously good and test well you can reuse them, depending on how they look:


Straighten the boiler so the mating surfaces are as flat as possible. Fit all four elements, making sure the gaskets are all fitting snug to the mating surface. I tighten the four bolts on each element as evenly as possible to maintain an even seal and prevent distortion, and i tighten them until good gasket compression is noticed.

Fit the new coupler to the steam exit tube on the boiler, and leave the hose clamps loose enough to move. The boiler must go in on an angle, there is a couple stainless steel guides on it and the cabinet to help. The fill hose must be fitted prior to installing the boiler. Once in place and firmly pressed back toward the cabinet, the hose clamps can be tightened on the coupler.

Fit the star connections to the boilers as well as the three phases to their correct terminal on the elements. Slide the probe into its pocket. Push the thermo-couple into the tube on the element. Refit the motor and pump out hose. Connect the motor to its power plug.

At this point i fill the boiler manually and check for leaks, mainly around the pump housing and the elements. If the elements leak, tighten them a bit more.

When youre happy its not leaking, refit the level sensor. At this point the oven should be mostly reassembled. Fit the motor holding bolts, check the nuts holding the boiler, check electrical connections, check thermo-couple and probe.

Next step is to locate the faulty relay that caused the failure. They are clearly marked with A1/A2 on one terminal, and the other two terminals are B1 and B2, putting the meter on ohms, one probe to A1/2 and check the B sides, should read open or in the meg ohms. If you get a reading of 15-40 ohms, that relay is fine and it is indicating a short on another relay. When you find the shorted relay, remove it and recheck the others to be sure. Replacing these will require anything from a PH#2 screwdriver to a TORX bit or both, depending on the model. Its very easy, but note wire locations. Mount them firmly to their heatsink.

Check everything prior to restoring power, if the safety chain has been tripped the reset is inside the front panel, an Allen key in the top opens that. Operate the oven on steam for a few minutes and watch for leaks, stay clear while power is turned on. Turn off mains prior to touching anything.

Reinstall side panel when youre satisfied all is well.

While this can be performed by anyone with reasonable mechanical ability and basic electrical skills, it should not be done by anyone not holding an appropriate licence in areas where it is required.