Product Overview

Restore proper temperature-sensor positioning and protect the sensing element inside a compatible Raypak pool or spa heater with the Raypak 003765F Sensor Well Kit. This genuine Raypak replacement part is also commonly referred to as a thermowell.

The sensor well installs in the heater’s water header and creates a sealed pocket for the temperature sensor. Pool water transfers heat through the metal wall of the well, allowing the sensor to monitor water temperature without being directly exposed to circulating water.

A damaged, corroded, leaking, or heavily scaled sensor well can interfere with temperature readings and may allow water to leak around the sensor opening. Replacing the well helps restore proper sensor placement and a secure seal at the heater header.

The kit includes a stainless-steel thermowell, brass threaded fitting, and sealing O-ring. The temperature sensor itself is not included. Raypak recommends genuine factory-authorized replacement parts because they are designed to meet the manufacturer’s original performance requirements.

Key Features

• Genuine Raypak factory-authorized replacement part
• Stainless-steel thermowell construction
• Brass threaded mounting fitting
• Includes sealing O-ring
• Protects the temperature sensor from direct water exposure
• Supports accurate water-temperature monitoring
• Helps repair leakage around the sensor opening
• Direct replacement for compatible Raypak heaters
• Designed for installation in the water header
• Temperature sensor is sold separately

Specifications

Published replacement-part measurements identify an approximately 3⅜-inch stainless-steel tube, ½-inch male pipe thread, brass fitting, and included O-ring.

Compatibility

The 003765F sensor well is used with numerous compatible Raypak heater families, including select:

• 105A and 105B heaters
• 185 through 405 heater models
• 185A through 405A models
• 185B through 405B models
• Digital 206A, 266A, 336A and 406A heaters
• Low NOx 207A, 267A, 337A and 407A heaters
• Additional 206 through 408 configurations using the same sensor-well assembly

Compatibility depends on the complete model number, production date, water-header design, and parts revision. Verify the heater identification label and applicable Raypak parts diagram before ordering.

Installation Information

Turn off electrical power, close the gas supply, stop the circulation pump, and relieve all system pressure before servicing the heater. Allow the heater to cool and drain the water header as necessary.

Remove the temperature sensor carefully before loosening the existing well. Inspect the header threads and sealing surface for corrosion, cracks, debris, or scale. Install the supplied O-ring in the correct position and thread the new assembly into the header without overtightening it.

Reinstall the sensor fully inside the well and secure it according to the heater service instructions. Restart circulation and inspect the connection for leaks before operating the burner.

Professional installation by a qualified pool-heater technician is recommended.

Package Contents

• One stainless-steel sensor well
• One brass threaded fitting
• One sealing O-ring

The temperature sensor, wiring, header, control board, installation tools, and labor are not included.

Warranty Information

Warranty coverage is subject to Raypak’s current replacement-part terms, proof of purchase, correct application, and proper installation. Damage caused by freezing, corrosion, overtightening, damaged header threads, improper installation, or incompatible equipment may not be covered.