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Vulcan oven not heating
I’m working on a Vulcan oven, model VC4ED, for the school district that I work for. I got a call saying the temperature ramped up from 350 degrees to almost 500 degrees and then came back down to about 250 degrees. I suspected it to be the temperature probe or temperature control board, so I changed them both. Well I was wrong because it’s still not working. I checked the high limit switch and it is closed. I changed the contactor for the heating elements, thinking it may have been a bad contactor coil, still not working. Checked input power to temperature control board, I have 208V. Checked output voltage/control voltage at temperature control board, have 208V. I have 208V control going to the fan contactor coil, and it’s pulling in and the fan is running. But I don’t have 208V of control voltage going to the coil on the contactor for the heating element. Any advice is greatly appreciated.
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5 Replies
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I believe that unit has a control board with a relay that sends 24V to the coil. the neutral side going to the high limit.
If that is the set up you have I would say it sounds like the relay on the control board is sticking, or the contactor is sticking. Depending on if you have coil voltage while its calling for heat.
Also make sure they have nothing blocking the flue, and that the air is flowing up and out of the flue.
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Tito, this unit is line voltage controlled. see page 62 of this manual;VH-VC4ED_sm.pdf (static-pt.com)
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What your describing sounds a lot like you have a electronic temp control with a RTD sensor that is bad. This makes a heat call that opens the high limit that then resets and heats to the limit again. With a DVOM set to ohms, check the temp probe at the board unplugged..
For accurate help on Vulcans, due to model changes I would need the ML number and serial number. There was a major wiring change at 481916864.
Also the polarity of the probe.
If the unit has solid state relays on the main board, they may be holding in to run the heaters overtempt.
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BTW, make sure the board cooling fan is operating. Electronics don’t like heat.
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I’ve seen that oven made by several manufacturers. I’m not sure about VULCAN, but some of them had an issue w the temp control boards and sensors. I believe they switched from a thermistor type probe to an RTD so you have to make sure the probe matches the control board. They look identical, but are not. We had a customer w in house maintenance and they were mismatching them. I think that circuit goes from the control board to the high Limit, then the contactor, so jump out the board, and if that doesn’t get voltage to your contactor coil, try jumping the limit.
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