{"product_id":"thermal-switch-fuse-replacement-for-eti®-400-and-eti®-250-heater-p475998","title":"Pentair ETi 400 \u0026 ETi 250 Heater Thermal Switch Fuse 475998","description":"\n\u003ch2\u003ePentair ETi 400 \u0026amp; ETi 250 Heater Thermal Switch Fuse | 475998\u003c\/h2\u003e\n\n\u003cp\u003e\n    The \u003cstrong\u003ePentair 475998 Thermal Switch Fuse\u003c\/strong\u003e\n    is a genuine OEM replacement safety component for\n    compatible \u003cstrong\u003ePentair ETi 400 and ETi 250\u003c\/strong\u003e\n    high-efficiency swimming pool and spa heaters.\n\u003c\/p\u003e\n\n\u003cp\u003e\n    Designed for the heater's thermal protection system,\n    this component helps protect the equipment by\n    interrupting operation when specified thermal\n    safety conditions are exceeded.\n\u003c\/p\u003e\n\n\u003cp\u003e\n    Pentair identifies part number 475998 as the\n    thermal fuse used in its ETi heater systems.\n    This is a replacement safety component,\n    not a complete heater or control assembly.\n\u003c\/p\u003e\n\n\u003ch3\u003eProduct Features\u003c\/h3\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eGenuine Pentair OEM:\u003c\/strong\u003e Original manufacturer replacement component.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eETi 400 Compatibility:\u003c\/strong\u003e Designed for Pentair ETi 400 high-efficiency gas heaters.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eETi 250 Compatibility:\u003c\/strong\u003e Also specified for Pentair ETi 250 heaters.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eThermal Safety Protection:\u003c\/strong\u003e Part of the heater's temperature safety system.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eOEM Fitment:\u003c\/strong\u003e Designed to replace the original Pentair 475998 component.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eIndividual Replacement Part:\u003c\/strong\u003e Sold as one thermal switch fuse.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eProduct Specifications\u003c\/h3\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Pentair\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 475998\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eDistributor SKU:\u003c\/strong\u003e PUR-151-0305\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermal Switch \/ Thermal Fuse\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eColor Identification:\u003c\/strong\u003e White\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Pool and Spa Gas Heater Safety System\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCompatible Heater Models:\u003c\/strong\u003e ETi 400 and ETi 250\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 788379878108\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 1 Thermal Fuse\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eCompatible Pentair Heaters\u003c\/h3\u003e\n\n\u003cul\u003e\n    \u003cli\u003ePentair ETi 400 High-Efficiency Gas Heater\u003c\/li\u003e\n    \u003cli\u003ePentair ETi 250 High-Efficiency Gas Heater\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\n    \u003cstrong\u003eCompatibility Notice:\u003c\/strong\u003e\n    Verify your heater model and the original\n    component part number before ordering.\n    Not all Pentair gas heaters use the same\n    thermal protection components.\n\u003c\/p\u003e\n\n\u003ch3\u003eWhat Does the Thermal Fuse Do?\u003c\/h3\u003e\n\n\u003cp\u003e\n    The thermal fuse is an important safety\n    component within the heater's protection system.\n\u003c\/p\u003e\n\n\u003cp\u003e\n    It is designed to interrupt operation when\n    the specified thermal safety conditions occur,\n    helping protect the heater from potentially\n    hazardous operating conditions.\n\u003c\/p\u003e\n\n\u003cp\u003e\n    A failed or open thermal fuse may prevent\n    the heater from operating.\n\u003c\/p\u003e\n\n\u003cp\u003e\n    Because this component is part of the\n    heater's safety system, the cause of a\n    thermal fuse failure must be identified\n    and corrected before the heater is\n    returned to service.\n\u003c\/p\u003e\n\n\u003ch3\u003eWhen to Replace the Thermal Fuse\u003c\/h3\u003e\n\n\u003cp\u003e\n    Replacement may be necessary when a\n    qualified service technician confirms\n    that the original thermal fuse has failed.\n\u003c\/p\u003e\n\n\u003cul\u003e\n    \u003cli\u003eThe original thermal fuse has been diagnosed as open or defective.\u003c\/li\u003e\n    \u003cli\u003eThe component is physically damaged.\u003c\/li\u003e\n    \u003cli\u003eThe heater's service procedure specifies replacement.\u003c\/li\u003e\n    \u003cli\u003eA qualified technician has identified and corrected the underlying cause of failure.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\n    \u003cstrong\u003eSafety:\u003c\/strong\u003e\n    Never bypass, jumper, or defeat a heater\n    thermal fuse. Doing so can create a\n    serious fire or equipment safety hazard.\n\u003c\/p\u003e\n\n\u003ch3\u003eRelated Pentair ETi Heater Parts\u003c\/h3\u003e\n\n\u003cp\u003e\n    Find additional genuine Pentair heater\n    replacement components at Aqua Pool Supply.\n\u003c\/p\u003e\n\n\u003cul\u003e\n    \u003cli\u003e\n        \u003ca href=\"https:\/\/aquapoolsupply.com\/products\/pentairstackfluesensoreti400pen475601z\"\u003e\n            \u003cstrong\u003ePentair 475601Z – Stack Flue Temperature Sensor\u003c\/strong\u003e\n        \u003c\/a\u003e\n        – Replacement exhaust temperature sensor\n        for compatible Pentair ETi heaters.\n    \u003c\/li\u003e\n    \u003cli\u003e\n        \u003ca href=\"https:\/\/aquapoolsupply.com\/collections\/parts-list-pentair-eti-400-heater\"\u003e\n            \u003cstrong\u003ePentair ETi 400 Heater Parts Diagram\u003c\/strong\u003e\n        \u003c\/a\u003e\n        – Identify thermal fuses, sensors, ignition\n        components, and other replacement parts.\n    \u003c\/li\u003e\n    \u003cli\u003e\n        \u003ca href=\"https:\/\/aquapoolsupply.com\/collections\/parts-list-pentair-eti-250-heater\"\u003e\n            \u003cstrong\u003ePentair ETi 250 Heater Parts Diagram\u003c\/strong\u003e\n        \u003c\/a\u003e\n        – Browse model-specific ETi 250 heater components.\n    \u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eInstallation and Safety\u003c\/h3\u003e\n\n\u003cp\u003e\n    Installation should be performed by a qualified\n    pool heater service technician following\n    Pentair's official service instructions.\n\u003c\/p\u003e\n\n\u003cul\u003e\n    \u003cli\u003eDisconnect electrical power before servicing the heater.\u003c\/li\u003e\n    \u003cli\u003eShut off the gas supply when required by the service procedure.\u003c\/li\u003e\n    \u003cli\u003eAllow the heater to cool completely.\u003c\/li\u003e\n    \u003cli\u003eDiagnose the cause of the thermal fuse failure.\u003c\/li\u003e\n    \u003cli\u003eVerify that Pentair 475998 is the correct replacement part.\u003c\/li\u003e\n    \u003cli\u003eInstall the replacement according to the manufacturer's instructions.\u003c\/li\u003e\n    \u003cli\u003eVerify proper safety system operation before returning the heater to service.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003ePackage Contents\u003c\/h3\u003e\n\n\u003cp\u003e\n    \u003cstrong\u003eIncludes:\u003c\/strong\u003e One (1) Genuine Pentair\n    475998 Thermal Switch Fuse.\n\u003c\/p\u003e\n\n\u003cp\u003e\n    \u003cstrong\u003eNot Included:\u003c\/strong\u003e Heater control board,\n    wire harness, stack flue sensor, or complete heater.\n\u003c\/p\u003e\n\n\u003cp\u003e\n    \u003cstrong\u003eSelling Quantity:\u003c\/strong\u003e 1 Thermal Fuse.\n\u003c\/p\u003e\n","brand":"Pentair","offers":[{"title":"Default Title","offer_id":52731562754364,"sku":"475998","price":79.94,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0736\/3280\/9276\/files\/Screenshot2026-11-10141637.png?v=1794345411","url":"https:\/\/aquapoolsupply.com\/products\/thermal-switch-fuse-replacement-for-eti%c2%ae-400-and-eti%c2%ae-250-heater-p475998","provider":"Aqua Pool Supply","version":"1.0","type":"link"}