Home » Aquastat Immersion Well 3/4 Inch with Clamp | Replaces Honeywell 121371B | NBK-20930K
NBK-20930K – Aquastat 3/4 Inch, Well, with Clamp – (Special Order) - Total Hearth
NBK-20930K – Aquastat 3/4 Inch, Well, with Clamp – (Special Order) - Total Hearth
NBK

Aquastat Immersion Well 3/4 Inch with Clamp | Replaces Honeywell 121371B | NBK-20930K

In stock
SKU: SO-20930K
(0)
$19.99
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NBK-20930K – Aquastat Immersion Well 3/4 Inch with Clamp | Replaces Honeywell 121371B

The NBK-20930K Aquastat Well Assembly is a precision 3/4 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. Secure thermal contact 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

  • 3/4 Inch Immersion Well – Larger standard size fits most 3/4" aquastat sensor bulbs for accurate, reliable temperature sensing
  • Clamp Included – Secures the sensor bulb firmly in place, eliminating movement that causes erratic temperature readings
  • Corrosion-Resistant Construction – Built to withstand system pressure and moisture for long-term, dependable service
  • Direct OEM Replacement – Drop-in replacement for Honeywell 121371B and Grainger 3XK90
  • Broad Compatibility – Works with most standard aquastat controllers used in outdoor boiler and hydronic heating applications

Specifications

  • SKU: NBK-20930K
  • Part Number: 20930K-NBK
  • Well Size: 3/4 inch
  • Includes: Immersion well and clamp
  • Application: Outdoor wood boilers, hydronic heating, hot water tanks

Replaces / Cross-Reference

  • Honeywell: 121371B
  • Grainger: 3XK90

Common Applications

  • Outdoor wood boilers and biomass boilers
  • Hydronic baseboard and radiant floor heating systems
  • Hot water storage tanks using immersion aquastat controls
  • Commercial or residential hot water loops requiring 3/4" well sizing

Why Choose the NBK-20930K?

When your system requires a 3/4 inch immersion well, the NBK-20930K delivers the same reliable thermal coupling as the Honeywell 121371B and Grainger 3XK90 it replaces. The included positive-locking clamp holds the sensor bulb in firm contact with the water, ensuring accurate readings, efficient cycling, and long-term system protection.