What Can I Do About a Sticking Furnace Transducer?

Furnace Transducer

• A furnace transducer helps to regulate fuel emissions -- such as gas or oil -- by responding to changes in pressure within the furnace system. For example, when a thermostat calls for heat on a gas-powered system, the transducer enables the gas ignition to ignite. Once pressure conditions within a system reach a certain point, the transducer triggers an electrical current or turns off an electrical current. The current then turns on or turns off the fuel supply. Furnace transducers are preset to respond to certain pressure conditions. These presets help to ensure optimal furnace efficiency.

Transducer Components

• The components that make up a furnace transducer allow the device to be exposed to heated compartment conditions and gas exposures without sustaining damage. A transducer consists of an elastomeric diaphragm and an insulator casing. The elastomeric diaphragm responds to pressure changes by opening and closing the electrical circuit that regulates flow to the igniter. The insulator casing separates a transducer’s internal components from external conditions, which prevents high heat levels from impairing the device’s pressure sensitivity.

Circuit Malfunctions

• Circuit malfunctions occur whenever conditions within a heating system make it unsafe for the igniter to light. As with other heating system sensors and gauges, the furnace transducer works off of a main circuit control board. In order for a furnace transducer to work correctly, all other controls must also be closed in order to form a closed circuit. Irregularities affecting other sensors and gauges will cause one or more circuits to remain open. Testing the voltage to a furnace transducer can help determine if a break in the circuit exists. This requires the use of a Volt-Ohm meter, so only people who have experience working with electrical equipment should perform this test.

Air Flow

• As furnace compartments rely on a certain mixture of air and gases in order to burn fuel materials, air-flow blockages prevent a furnace from igniting. A dirty furnace filter can reduce needed air flows within the furnace compartment. A weak or faulty furnace blower device will also affect air flow through the unit. In some cases, a blower motor may have a failing capacitor. Fan capacitors deliver electrical current to the blower motor. Other factors affecting air flow include clogged or blocked vents leading to one or more rooms in the house. Vent blockages can also offset air flows inside the furnace compartment. When everything else in the system is working correctly, the furnace transducer may need to be replaced.