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Convotherm uneven cooking
Hello. Our Convoterm C4ED-10.10ES is heating unevenly. What could be the cause of this?
A few things, the heating element has been replaced by a custom reproduction. It was made 10 cm too wide in diameter due to a fault of the maker, and one circuit is not working. So the power is a little less then two thirds of the original 18.9kW. The mount point of the heating element is of course at the original placement, but the enlarged coil extends much more back to the rear panel of the oven. And the fan is still in original center. Maybe this “off center coil” causes it?
Also, the fan motor seems to make some noise during the clean cycle, and sometimes stop 10-20 min before end with the error E03.1.17 Motor overload. All three phases measures around 15 ohms. Motor spins very smooth and nice if I spin it with my fingers, but maybe a bearing is about to die. It’s a Hanning V3A145-040P0035-015-002OSO-819. Not sure if I’ll be able to replace it’s bearings. Not sure if this could add to the problem?
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5 Replies
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Interesting that you didn’t use a OEM heating element. Yes, it’s position and placement are important to proper airflow. Also the heating element’s design and quality will either heat even or have a hot spot in one area. All in the bending and forming of the Cal rod. The other thing with a aftermarket element is the clearances to insulation areas.. I have seen misplaced elements that caused rusting and erosion to a oven. There by shortening it’s lifespan.
Now with your motor, It has to be either something touching the blower wheel or a bearing. Or, the centrifugal switch inside the motor. Things move with heat expansion and cooling. But also the water from the cleaning cycle may be creating a load change. With liquid pumps, open flow will sometimes exceed design limits. I don’t think you can do that with air unless the density changes. Steam is heavier than hot air. but not cold air. But you may want to check the clean nozzles and flow rate..
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Cause the spare parts are extremely expensive here. From a pure parts supplier it was 15x the price I paid for the custom one, and through the company who sold the oven 33x the price (excluding the labour). I measured every part of it, and it should be a pure replica, but the factory messed up a few measurements. I’ve re-ordered the heating element with the correct measurements, so hopefully it solves it.
I wanted to take the motor apart, but it had some weird oval shaped screw heads. Have to take an tiny socket and cut a 3mm groove it in, so I can grab on to the screw.
What’s the centrifugal switch for? The motor only have 3 wires from it, so nothing more than the 3 phases.
I’ll also check the nozzles. But wouldn’t an obstructed nozzle mean less water, and that would make the motor load even lighter?
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I forgot they use digital pulse to monitor the motor load and RPM. just so used to blower motors having a speed safety involved. Now the motor load monitor software may be on the low side. I’d measure it. The flow of air is very precise, so if a damper or vent slot is not where is belongs, or larger than calibrated for it may trip the safety value. Make sure you have the right version of software.
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Where can I find the vents or damper?
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The airflow path. where does the air come from and go to. The inflow will be right in front of the blower wheel. From there it will go over and through the heaters. Then to the discharge ports and flow directors. Convection ovens have to have very exacting flows to cook evenly. When you replaced the heating element you should have been able to see the discharge paths. Usually through the oven chamber jacket to certain points that make the flow even top to bottom, Side to side. Anything that can interrupt just one of the discharge paths will corrupt the flow during cooking. Including just a minor misalignment.
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