--- 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: "C$3605" currency: NIO in_stock: true reviews_count: 8 url: https://www.desertcart.ni/products/43369036-optimum-pool-technologies-high-limit-switch-compatible-replacement-for-pentair store_origin: NI region: Nicaragua --- # 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:** C$3605 **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?** C$3605 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.ni](https://www.desertcart.ni/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 Full description not available ## Features - Replacement High Limit Switch (135°F) for Pentair Sta-Rite MasterTemp & Max E Therm Pool Heaters - Replaces Part No. 42001-0063S & STA-151-6255 - Compatibility: Pentair MasterTemp (All Models) & Max-E-Therm (Models SR200, SR333, SR400) Heaters - Manufactured by Optimum Pool Technologies ## 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 ### ⭐⭐⭐⭐⭐ Easy DIY repair job for HLS error on your heater *by A***2 on Reviewed in the United States 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. ### ⭐⭐⭐⭐⭐ Great Quality - But... *by D***B on Reviewed in the United States 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. ### ⭐ DANGER, DANGER, DANGER: Out of Specification!!! *by J***R on Reviewed in the United States on July 29, 2018* Danger: I just received two of these High Limit Switches from Amazon, and I tested them against Pentair's specification of 135 Deg. F for switching the pool heater off. They both failed to operate until dangerously high temperatures. One operated at 147.5 Deg. F, and the other operated at 145.3 Deg. F. Note that 3rd degree burns are near instantaneous if skin comes in contact with 145 Degree water. I believe Amazon should immediately suspend sales of this item, and Amazon and the manufacturer (a company call Optimum, NOT Pentair) should issue a recall of these devices, and contact the Consumer Product Safety Commission. This is a critical part of the safety system for the Pentair pool heater. I have access to laboratory grade thermal test equipment, including digital thermometers and a precision circulating water bath that I used in the testing. Each unit was tested multiple times, and the results were essentially identical. Most customers would not do this testing, and would think there were being protected by this switch. They would not be protected. --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.ni/products/43369036-optimum-pool-technologies-high-limit-switch-compatible-replacement-for-pentair](https://www.desertcart.ni/products/43369036-optimum-pool-technologies-high-limit-switch-compatible-replacement-for-pentair) --- *Product available on Desertcart Nicaragua* *Store origin: NI* *Last updated: 2026-04-22*