Lochinvar & A.O. Smith 100208653 Flow Switch

The Lochinvar & A.O. Smith 100208653 Flow Switch is a critical OEM replacement part engineered for high-precision water flow detection in Knight fire tube boilers and high-efficiency water heaters. This indoor flow switch features a robust brass bushing and a factory-calibrated paddle mechanism designed to provide reliable system feedback, ensuring the burner only fires when adequate circulation is present. Built to NEMA 1 standards, it serves as a direct cross-reference for legacy part numbers WTR2040, WTR2040K, and 100173696. For technicians service-calling Lochinvar Knight KH55-285 models or Heating Series WB units, this switch is the standard for restoring safety protocols and preventing dry-fire conditions. The 100208653 is designed for seamless integration with the existing HVAC control board, offering the durability required for demanding hydronic heating environments and high-cycle commercial or residential applications. Rely on this genuine Lochinvar part to maintain peak boiler system efficiency and prevent intermittent low-flow lockouts.

• Direct OEM Compatibility: Engineered specifically for Lochinvar Knight and A.O. Smith commercial systems, replacing WTR2040 and WTR2040K without field modifications.
• Heavy-Duty Construction: Features a corrosion-resistant brass bushing and durable paddle assembly to withstand constant fluid velocity and thermal stress.
• System Safety: Operates as a primary safety interlock to prevent heat exchanger damage by ensuring the pump is moving sufficient GPM before ignition.
• Standardized Housing: The NEMA 1 enclosure protects internal electrical contacts from dust and debris in indoor mechanical rooms.

What are the symptoms of a failing 100208653 flow switch?
Common indicators include "No Flow" error codes on the boiler display, the burner failing to ignite despite the pump running, or intermittent system lockouts. Often, scale buildup on the paddle or a fatigued internal spring prevents the switch from closing the circuit.

Can I use this switch for outdoor installations?
No, this specific model is rated for indoor use only. For exterior units, a switch with a higher NEMA rating (such as NEMA 4X) would be required to protect against moisture and environmental exposure.

Are the paddles included with the switch?
Yes, the 100208653 kit includes the necessary paddle assembly to ensure proper displacement and accurate flow sensing across compatible pipe diameters.

This item is not eligible for free shipping.

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.