Alpha NTC Temperature Probe 1.033784

The Alpha 1.033784 is a negative temperature coefficient (NTC) probe used on Alpha gas boilers. An NTC sensor changes resistance as its temperature changes, which lets the boiler's control board read the temperature at the point where the probe is fitted and regulate the appliance accordingly. It is listed by Alpha under the sensor part type and is used across the Eco 2 and InTEC 2 appliance families.

• The boiler locks out or fails to fire, with a fault code pointing to a temperature sensor circuit.
• Domestic hot water temperature becomes erratic, running hot then cold without a change at the tap.
• The appliance cycles or modulates poorly because the control board is reading an incorrect temperature.
• Resistance readings from the probe fall outside the expected range for the ambient or system temperature when tested with a multimeter.
• Intermittent faults that appear when the boiler is warm and clear once it has cooled, a common pattern with failing NTC sensors.

• Confirm the appliance model and, where shown on the data badge, the GC number against the compatibility list before ordering.
• Check the existing probe and its connector type against the part number 1.033784 to make sure the correct sensor is being replaced.
• Note the alternative number 1258681 when cross-referencing against older Alpha documentation or stock records.
• This item is not classified as a gas part; work on the appliance should still follow the manufacturer's instructions and any applicable regulations.