---
product_id: 43369036
title: "Optimum Pool Technologies® High Limit Switch Compatible Replacement for Pentair MasterTemp & Max-E-Therm Heaters - Compatible Replacement for 42001-0063S"
brand: "optimum pool technologies"
price: "€ 58.70"
currency: EUR
in_stock: true
reviews_count: 8
category: "Optimum Pool Technologies"
url: https://www.desertcart.at/products/43369036-optimum-pool-technologies-high-limit-switch-compatible-replacement-for-pentair
store_origin: AT
region: Austria
---

# Part Replacement Easy Install 135°F Limit Optimum Pool Technologies® High Limit Switch Compatible Replacement for Pentair MasterTemp & Max-E-Therm Heaters - Compatible Replacement for 42001-0063S

**Brand:** optimum pool technologies
**Price:** € 58.70
**Availability:** ✅ In Stock

## Summary

> 🔥 Keep Your Pool Perfectly Heated!

## Quick Answers

- **What is this?** Optimum Pool Technologies® High Limit Switch Compatible Replacement for Pentair MasterTemp & Max-E-Therm Heaters - Compatible Replacement for 42001-0063S by optimum pool technologies
- **How much does it cost?** € 58.70 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.at](https://www.desertcart.at/products/43369036-optimum-pool-technologies-high-limit-switch-compatible-replacement-for-pentair)

## Best For

- optimum pool technologies enthusiasts

## Why This Product

- Trusted optimum pool technologies brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **🌊 Universal Fit:** Compatible with all Pentair MasterTemp and select Max-E-Therm models.
- • **💪 Durable Design:** Manufactured by Optimum Pool Technologies for long-lasting performance.
- • **🔒 Reliable Safety:** Ensures your pool heater operates within safe temperature limits.
- • **🔄 Seamless Compatibility:** Perfectly replaces 42001-0063S & STA-151-6255 for hassle-free upgrades.
- • **🛠️ Effortless Installation:** Designed for quick and easy installation, getting you back to enjoying your pool.

## Overview

The Optimum Pool Technologies 42001-0063S High Limit Switch Replacement is designed for Pentair MasterTemp and Max-E-Therm heaters, ensuring safe operation at a maximum temperature of 135°F. This reliable replacement part is compatible with all MasterTemp models and select Max-E-Therm models, making it an essential upgrade for pool maintenance enthusiasts.

## Description

Product description OPTIMUM Heater Replacement Parts Optimum Pool Technologies manufacturers high quality replacement parts for the most common pool heaters on the market today. When your heater needs a repair, fix it the OPTIMUM way! Hi Limit Switch Replacing your broken Hi Limit Switch is easy! Two spades located on top of the switch provide easy installation into the heater manifold. Existing color coded wires can be unplugged from old switch and reused when replacing. Compatible Replacement for OEM Part No 42001-0063S MasterTemp Schematic Compatible Replacement for Pentair MasterTemp & Max-E-Therm Pool Heaters The High Limit Switch is an important switch in your Max-E-Therm or MasterTemp pool heater, and is used to detect when your water temperature has exceeded a safe level (135°F) and immediately opens the heat exchanger outlet when that happens. You MasterTemp heater will indicate when it is time to replace the High Limit Switch when the “HLS” LED is displayed. #6 On Schematic Compatible Replacement for MasterTemp & Max-E-Therm : Other Common Replacement Parts Stack Flue Sensor: Part No OPT-42002-0024S A stack flue sensor, located on the exhaust elbow of a pool heater, prevents the flue gas output from exceeding 500°F. When this fails, your system will show error codes E 05 o r E 06 t o indicate that the stack flue sensor must be replaced. This replacement stack flue sensor from Optimum Pool Technologies is a Compatible Replacement for Pentair’s MasterTemp, Max-E-Therm, and other heaters. It is designed specifically as a Compatible Replacement for Sta-Rite heater stack flue sensor. Heater Pressure Switch: Part No 42001-0060S The water pressure switch functions by turning off the burner if the water flow is interrupted. If the water flow is restricted, the water pressure switch may prevent the burner from firing and cause the “Service System” light to go on . If the light remains on after the filter has been serviced, have a qualified service technician check the system. Gas Shutoff Switch: Part No OPT-0025S The Gas Shutoff Switch is an important switch in your Max-E-Therm or MasterTemp pool heater, and is used to detect when your heat exchanger outlet temperature has exceeded a safe level (140°F) and the switch immediately opens when that happens. You MasterTemp heater will indicate when it is time to replace the Gas Shutoff Switch when the “A GS” LED i s displayed. Heater Thermistor: Part No OPT-42001-0053S If the temperature on your control panel’s display is s howing an incorrect temperature, your thermistor may need to be replaced. Thermistors often display a temperature that is much too high when they reach the end of their lifespan. Fix this issue easily by replacing your worn-out thermistor temperature sensor with this Optimum replacement brass thermistor.

Review: Great Quality - But... - If you're buying this due to the Diagnostic LED on your Pentair stating it's the High Limit Switch, there is a very good possibility that it is actually a corroded Thermal Regulator, also located in the Manifold. My heater would heat on and off and was taking a long time to heat my spa. LED indicated it was the HLS. Bought this to replace, but heater still had the same issue and LED indicator. After exhaustive internet searches, I located lots of info stating that this issue is commonly due to a corroded Thermal Regulator. Sure enough, replacing it solved my problem and heater runs great now.
Review: Excellent. - Worked perfectly. Even came with the tape dope already in place. Just had to Screw out the old + screw in the new.

## Features

- High Limit Switch (135°F) Compatible Replacement for Pentair Sta-Rite MasterTemp & Max E Therm Pool Heaters
- Compatible Replacement for Part No. 42001-0063S & STA-151-6255
- Compatible Replacement for: Pentair MasterTemp (All Models) & Max-E-Therm (Models SR200, SR333, SR400) Heaters
- Manufactured by Optimum Pool Technologies
- NOTE: This is a compatible aftermarket replacement part. The manufacturers' names and part numbers have been used for reference purposes only. Optimum Pool Technologies Inc is an independent brand.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B01HJ2NI5A |
| Actuator Type | Push Button |
| Best Sellers Rank | #793,806 in Patio, Lawn & Garden ( See Top 100 in Patio, Lawn & Garden ) #1,249 in Swimming Pool Heater Parts |
| Brand | Optimum Pool Technologies |
| Brand Name | Optimum Pool Technologies |
| Circuit Type | 1-way |
| Color | Brass |
| Compatible Devices | Pentair Max-E-Therm, Pentair MasterTemp |
| Connectivity Protocol | X-10 |
| Connector Type | Plug In |
| Contact Material | Metal |
| Contact Type | Normally Closed |
| Control Method | Push Button |
| Controller Type | Push Button |
| Customer Reviews | 4.4 out of 5 stars 62 Reviews |
| International Protection Rating | IP00 |
| Manufacturer | Optimum Pool Technologies |
| Material Type | Metal, Plastic |
| Model | OPT-0063S |
| Mounting Type | Panel Mount |
| Number of Items | 1 |
| Number of Positions | 1 |
| Operation Mode | automatic |
| Part Number | OPT-0063S |
| Switch Type | Limit Switch, Temperature Switch |
| Terminal | Screw |
| Unit Count | 1 Count |
| Upper Temperature Rating | 135 Degrees Fahrenheit |

## Images

![Optimum Pool Technologies® High Limit Switch Compatible Replacement for Pentair MasterTemp & Max-E-Therm Heaters - Compatible Replacement for 42001-0063S - Image 1](https://m.media-amazon.com/images/I/31IvRm5RjiL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Great Quality - But...
*by D***B on May 22, 2018*

If you're buying this due to the Diagnostic LED on your Pentair stating it's the High Limit Switch, there is a very good possibility that it is actually a corroded Thermal Regulator, also located in the Manifold. My heater would heat on and off and was taking a long time to heat my spa. LED indicated it was the HLS. Bought this to replace, but heater still had the same issue and LED indicator. After exhaustive internet searches, I located lots of info stating that this issue is commonly due to a corroded Thermal Regulator. Sure enough, replacing it solved my problem and heater runs great now.

### ⭐⭐⭐⭐⭐ Excellent.
*by J***B on January 2, 2020*

Worked perfectly. Even came with the tape dope already in place. Just had to Screw out the old + screw in the new.

### ⭐⭐⭐⭐⭐ Easy DIY repair job for HLS error on your heater
*by A***2 on March 4, 2018*

My Pentair 400,000 Btu pool heater stopped running and gave me the "Service Heater" light on the control panel. The indicator light on the backside of the panel showed "HLS", meaning a problem with the High Level Switch part. After following the diagnostic tree in the manual (i.e. I knew I didn't have excessively hot water coming out as the heater never fired up) it was clear that the switch had gone bad. A few online videos showed that getting into the heater was pretty simple and replacing the sensor was a straight forward job. This switch proved a perfect "drop in" replacement for the original and, after a trip to the hardware store, I had my pool heater back in business. You can see the pictures for why I had to make a run to the store. The teeth on the outside of the sensor are for the wire clamps to slip on and make the connection. My original sensor's teeth had rusted so badly that they came apart when I tried to unplug and I could get the broken teeth out. Took the new sensor with me so I could test out and buy the right size connectors as I only wanted to make this drive one time. An 18mm wrench is the right size for removing/reinstalling the senor. Save yourself from the high prices of the pool store or an expensive repair call - this one is an easy DIY repair.

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*Product available on Desertcart Austria*
*Store origin: AT*
*Last updated: 2026-06-03*