Lochinvar & A.O. Smith 100167786 Time Delay Module

For experienced service technicians working on Lochinvar or A.O. Smith high-efficiency hydronic systems, the Lochinvar 100167786 Time Delay Module is the required OEM replacement to maintain factory-spec sequencing. This component is identical to part number RLY3003 and provides critical timing control for the startup and post-purge cycles. In high-demand residential and commercial applications, this module regulates the timing of the circulator pump relay and the combustion air blower, preventing thermal stress on the heat exchanger. By managing the post-purge operation, it ensures that residual heat is effectively moved out of the combustion chamber after the burner shuts down, which is essential for protecting the Smart System control board and preventing nuisance limit-trips or short cycling. This is a direct-fit genuine OEM part, ensuring that voltage tolerances and delay intervals match the original equipment design for seamless integration with existing wiring harnesses.

Key Benefits for Professionals

• Direct OEM Integration: Replaces Lochinvar RLY3003 without any field modifications, maintaining the integrity of the original control circuit.
• Equipment Protection: Prevents short cycling and manages post-purge timing to decrease the thermal load on internal components, extending the life of the heat exchanger.
• Precision Timing: Engineered to provide accurate electrical sequencing for high-efficiency boilers and commercial water heaters.
• Versatile Compatibility: Designed for use across various Lochinvar and A.O. Smith platforms, including Knight boilers and Armor water heaters.
• Field Reliability: Built to meet strict factory standards, reducing the risk of call-backs caused by unstable timing in the ignition or pump-run sequence.

Common Questions

Is the 100167786 a direct swap for the RLY3003?
Yes, the Lochinvar 100167786 is the updated manufacturer part number and is functionally identical to the RLY3003. It installs into the same mounting footprint with the same electrical connections.

What symptoms indicate a failing time delay module?
Technicians often see issues where the circulator pump fails to engage for the post-purge cycle, or the burner shuts down prematurely without the proper delay, often leading to overheating codes or flame failure lockouts.

Can I use a generic off-the-shelf delay relay instead?
Using generic relays is not recommended. The 100167786 OEM module is calibrated to specific timing intervals required by Lochinvar and A.O. Smith logic controllers to ensure safe and efficient ignition and shutdown sequences.

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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.