Field Controls 46086900 Safety Switch

Specifically engineered for oil-fired appliances, the Field Controls 46086900 (Model WMO-1) is a heavy-duty manual reset thermal safety switch designed to protect systems operating under negative pressure. This blocked vent safety switch monitors flue gas temperatures and automatically interrupts the burner circuit if it detects hazardous conditions, such as a vent blockage, continuous downdrafting, or flue gas spillage. Rated for 120Vac and calibrated to open at 200 degrees Fahrenheit, the WMO-1 safety switch serves as a critical fail-safe, preventing the burner from restarting until the issue is manually addressed by a technician. This SPST thermal cutoff features durable silver contacts and a heat transfer tube that ensures a rapid, precise response to rising exhaust temperatures. Whether you are performing a new installation on a chimney-vented system or replacing a failed oil burner safety control, this electromechanical device provides the reliable interruption required to maintain safe combustion environments in residential and commercial heating applications.

• Enhanced Equipment Protection: Instantly deactivates the burner upon sensing 200°F flue gas backup, preventing carbon monoxide risks.
• Rugged Silver Contacts: Equipped with high-conductivity silver contact material for a 10 Amp load rating and long-term switching reliability.
• Manual Reset Security: The manual reset feature ensures the appliance cannot cycle back on until the underlying venting restriction is identified and resolved.
• Versatile Application: Ideal for power venting and natural draft oil-fired furnaces, boilers, and water heaters.
• Negative Pressure Optimized: Specifically recommended for appliances where the vent system normally maintains negative pressure.

What causes a manual reset thermal safety switch to trip?
A trip is typically triggered by a blocked vent, a failing draft inducer, or inadequate draft caused by external environmental factors. The switch responds to the heat of the flue gases backing out of the heat transfer tube.

Can the 46086900 be used on gas-fired equipment?
The WMO-1 model is specifically designed for oil-fired applications. For gas-fired millivolt or 24V systems, a GSK series switch with gold-plated contacts is generally required to maintain proper circuit continuity.

Where should the WMO-1 safety switch be mounted?
It is typically mounted on the barometric draft control or the draft hood. It must be positioned so the heat transfer tube can effectively monitor the air stream for spillage.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.