Aquastat Well Clamp | Replaces Honeywell 121371AA | NBK-20929-1

NBK-20929-1 – Aquastat Well Clamp | Replaces Honeywell 121371AA

The NBK-20929-1 Aquastat Well Clamp is engineered to firmly secure aquastat sensor bulbs inside immersion wells in outdoor wood boilers, hydronic heating systems, and water heaters. A loose sensor bulb means inaccurate temperature readings, erratic cycling, and wasted energy — the NBK-20929-1 eliminates that problem with a positive-locking clamp that holds the bulb in firm thermal contact with the well at all times.

Key Features

• Positive-Locking Clamp Design – Holds aquastat sensor bulbs tightly in place for accurate, stable temperature readings
• Heavy-Duty Construction – Resists vibration and loosening under continuous heating system operation
• Easy Installation – Simple clamp design fits common aquastat well sizes used in hydronic and boiler systems
• Direct OEM Replacement – Drop-in replacement for Honeywell 121371AA with no modifications required
• Broad Compatibility – Works with most standard aquastat immersion wells in outdoor boiler and hydronic heating applications

Specifications

• SKU: NBK-20929-1
• Part Number: 20929-1-NBK
• Application: Secures aquastat sensor bulbs into immersion wells for stable temperature control

Replaces / Cross-Reference

• Honeywell: 121371AA

Common Applications

• Outdoor wood boilers and biomass boilers
• Hydronic baseboard and radiant floor heating systems
• Residential and commercial water heater installations
• Any system using aquastat immersion wells requiring secure sensor attachment

Why Choose the NBK-20929-1?

When an aquastat sensor bulb shifts or rattles loose inside its well, your heating system loses the accurate temperature feedback it needs to operate efficiently. The NBK-20929-1 restores that precision with a durable, vibration-resistant clamp that keeps the sensor locked in optimal thermal contact — a direct, cost-effective replacement for Honeywell 121371AA.