Home » Aquastat Immersion Well 1/2 Inch with Clamp | Replaces Honeywell 121371A | NBK-20929K
NBK-20929K – Aquastat 1/2 Inch Well with Clamp – (Special Order) - Total Hearth
NBK-20929K – Aquastat 1/2 Inch Well with Clamp – (Special Order) - Total Hearth
NBK

Aquastat Immersion Well 1/2 Inch with Clamp | Replaces Honeywell 121371A | NBK-20929K

In stock
SKU: SO-20929K
(0)
$19.99
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NBK-20929K – Aquastat Immersion Well 1/2 Inch with Clamp | Replaces Honeywell 121371A

The NBK-20929K Aquastat Well Assembly is a precision 1/2 inch immersion well complete with a securing clamp, engineered to house aquastat sensor bulbs for accurate temperature measurement in outdoor wood boilers, hydronic heating systems, and hot water tanks. Proper thermal coupling between the sensor and the water means your aquastat controller reads true temperatures — keeping your system safe, efficient, and running exactly as designed.

Key Features

  • 1/2 Inch Immersion Well – Standard size fits most aquastat sensor bulbs for accurate, reliable temperature sensing
  • Clamp Included – Secures the sensor bulb firmly in place, eliminating movement that causes erratic readings
  • Corrosion-Resistant Construction – Built to withstand system pressure and moisture for long-term, dependable service
  • Direct OEM Replacement – Drop-in replacement for Honeywell 121371A and Grainger 50PL45
  • Broad Compatibility – Works with most standard aquastat controllers used in outdoor boiler and hydronic heating applications

Specifications

  • SKU: NBK-20929K
  • Part Number: 20929K-NBK
  • Well Size: 1/2 inch
  • Includes: Immersion well and clamp
  • Application: Outdoor wood boilers, hydronic heating, hot water tanks

Replaces / Cross-Reference

  • Honeywell: 121371A
  • Grainger: 50PL45

Common Applications

  • Outdoor wood boilers and biomass boilers
  • Hydronic baseboard and radiant floor heating systems
  • Hot water storage tanks using immersion aquastat controls
  • Any system requiring stable, accurate aquastat temperature sensing

Why Choose the NBK-20929K?

A loose or poorly fitted aquastat well leads to inaccurate temperature readings and inefficient system cycling. The NBK-20929K solves that with a snug-fitting 1/2 inch well and a positive-locking clamp that holds the sensor bulb securely in thermal contact with the water. It’s a straightforward, cost-effective replacement for Honeywell 121371A and Grainger 50PL45 that restores accurate control to your heating system.