Steam Boiler Maintenance

LUCCA A53 / Mini / Vivaldi: Testing the Steam Boiler Temperature Probe

If your Lucca A53 fails to heat steam, trips the GFCI on start-up, or displays the "110-120-ECO" or "96-97-ECO" error code, there may be a fault with the steam boiler temperature probe. Follow these instructions to test the probe with a multimeter.

Tools Needed:
- Multimeter
- Clip-style multimeter leads
- 15mm wrench
- Wire snips or scissors

1. Identify the steam boiler temperature probe.
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2. Snip the zip tie holding the temperature probe leads together. Pull back the insulators and separate the electrical connections.
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3. Use the 15mm wrench to unscrew the probe from the machine.
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4. Set your multimeter to the resistance setting (Ω) and set the range to the 20M setting. Touch the multimeter probes to the temperature probe leads or attach the multimeter clips.
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The temperature probe acts as a variable resistor, with the resistance value changing inversely in response to changes in ambient temperature. The resistance value decreases as the temperature of the probe increases and vice versa. At roughly room temperature the probe should display a resistance of between 200kΩ and 300kΩ (or 0.20MΩ to 0.30MΩ).

5. Warm the resistor up in your hand, while keeping an eye on the multimeter display. You should see the resistance value start to drop almost immediately as the probe warms up. Look for a steady decrease. Let go of the multimeter and watch as the resistance value climbs back up as the probe cools down.
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If your multimeter displays 0 resistance or infinite resistance (O.L.), the temperature probe is most likely faulty. If the temperature probe does not consistently respond to changes in temperature that is also an indication that it's likely faulty.