Laars Heating Systems RE0015900 Aquast

As a veteran HVACR technician, I know that maintaining the integrity of a high-limit safety circuit is non-negotiable. The Laars Heating Systems RE0015900 High Limit Aquastat is an OEM-spec manual reset temperature control designed specifically for hydronic boilers and volume water heaters. Operating within a 100°F to 225°F temperature range, this component acts as the final line of defense, breaking the burner circuit if the operating control fails or if there is a sudden loss of flow, preventing catastrophic overheating of the heat exchanger.

When swapping out an old L4008E1305 equivalent or servicing a Teledyne Laars unit, you need a control that won’t drift. This hydronic safety limit requires a physical reset once tripped, ensuring a technician investigates the root cause of the over-temperature condition—whether it's a scaled heat exchanger or a failing circulator. This is a direct replacement high-limit aquastat for various commercial and residential models, including the Laars Mighty Therm and Rheos series, providing the reliability required in high-demand mechanical rooms.

• Precise Overheat Protection: Integrated 100°F–225°F high-limit control prevents system water from reaching dangerous boiling points.
• Mandatory Manual Reset: Features a manual reset button that prevents automatic restarts, ensuring system issues are diagnosed before resuming operation.
• OEM Compatibility: Genuine Laars RE0015900 replacement part designed for seamless fitment in Mighty Therm, Mighty Max, and Rheos boilers.
• Professional Grade Durability: Engineered for high-limit safety applications in both hydronic heating and domestic hot water systems.
• Standardized Sensing: Compatible with standard immersion wells for accurate water temperature monitoring and rapid response times.

Common Questions

Can I replace a manual reset aquastat with an automatic reset model?
No. For safety and code compliance, a high-limit safety control must be manual reset. This ensures that if the system hits its maximum limit, it stays offline until a technician can verify the cause of the failure.

What causes this high limit to trip frequently?
Frequent tripping usually indicates a failure of the primary operating aquastat, a clogged heat exchanger reducing flow, or a circulator pump that is no longer moving water fast enough to dissipate heat after the burner cycles off.

Is the immersion well included with this part number?
This part number typically refers to the aquastat control head. When performing a boiler temperature control replacement, always verify if your existing well is compatible or if a new Laars immersion well is required for proper thermal transfer.

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.