EN121371B ELITE 3/4" NPT Aquastat Well – 3" Insertion, 1-1/2" Insulation (Replacement for Honeywell 121371B)

The EN121371B ELITE Aquastat Well is a precision-engineered copper immersion well designed for hydronic heating systems. Built as a direct replacement for Honeywell 121371B, this well provides accurate bulb placement and dependable thermal transfer for optimal system control and performance.

⚠️ Note: Well Clamp Assembly is sold separately and not included.

✅ Key Features

• Direct replacement for Honeywell 121371B aquastat well

• 3/4" NPT threaded connection for secure installation

• 3" insertion length for accurate sensor positioning

• Durable copper construction for long-lasting performance

• 1-1/2" insulation depth with 5/64" capillary diameter

• Compatible with standard 3/8" x 3" bulb size

📊 Technical Specifications

⚙️ Common Symptoms of a Bad Aquastat Well

If your aquastat well is failing, you may notice:

• Inaccurate or fluctuating temperature readings

• Poor system response or cycling issues

• Visible corrosion, leaks, or damage around the well

• Difficulty inserting or securing the bulb properly

🔄 Quick Reference Compatibility

• Honeywell 121371B (Direct OEM replacement)

• Fits hydronic heating systems requiring 3/4" NPT, 3" insertion, 1-1/2" insulation

❓ Frequently Asked Questions (FAQ)

Q: Is the clamp assembly included?
A: No, the clamp assembly is sold separately.

Q: What size bulb fits this well?
A: It is designed for 3/8" x 3" bulbs.

Q: What’s the benefit of copper construction?
A: Copper ensures excellent thermal conductivity and durability in heating systems.

Q: How do I know if this will fit my system?
A: Check your OEM part number (121371B) or confirm system requirements for 3/4" NPT, 3" insertion.

🔧 Aquastat Well Comparison Chart (Elite Series – Honeywell Replacements)