{"product_id":"haywardhseriesfdheaterthermistorfdxlter1931hppfdxlter1931","title":"Hayward H-Series FD Heater Thermistor | FDXLTER1931","description":"\u003cdiv class=\"product-description\"\u003e\n\n  \u003ch2\u003eHayward FDXLTER1931 Thermistor (Water Temperature Sensor) for Universal H-Series FD Heaters\u003c\/h2\u003e\n\n  \u003cp\u003e\n    The Hayward \u003cstrong\u003eFDXLTER1931\u003c\/strong\u003e is a genuine OEM \u003cstrong\u003ethermistor (water temperature sensor)\u003c\/strong\u003e used on Hayward\n    \u003cstrong\u003eUniversal H-Series Low NOx “FD”\u003c\/strong\u003e pool heaters. It measures water temperature and sends a signal to the heater control board\n    so the heater can regulate firing accurately and display correct temperature readings.\n  \u003c\/p\u003e\n\n  \u003ch3\u003eFits \/ Compatibility\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eHayward Universal H-Series FD heaters including:\n      \u003cstrong\u003eH150FDN\u003c\/strong\u003e, \u003cstrong\u003eH150FDP\u003c\/strong\u003e, \u003cstrong\u003eH200FDN\u003c\/strong\u003e, \u003cstrong\u003eH200FDP\u003c\/strong\u003e,\n      \u003cstrong\u003eH250FDN\u003c\/strong\u003e, \u003cstrong\u003eH250FDP\u003c\/strong\u003e, \u003cstrong\u003eH300FDN\u003c\/strong\u003e, \u003cstrong\u003eH300FDP\u003c\/strong\u003e,\n      \u003cstrong\u003eH350FDN\u003c\/strong\u003e, \u003cstrong\u003eH350FDP\u003c\/strong\u003e, \u003cstrong\u003eH400FDN\u003c\/strong\u003e, \u003cstrong\u003eH400FDP\u003c\/strong\u003e\n    \u003c\/li\u003e\n    \u003cli\u003eAlso commonly referenced for \u003cstrong\u003eUniversal HC \/ HDF\u003c\/strong\u003e heater configurations (verify your exact model and parts diagram)\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eCommon Symptoms of a Bad Thermistor\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eDisplayed water temperature is inaccurate or jumps around\u003c\/li\u003e\n    \u003cli\u003eHeater short-cycles or won’t maintain set temperature\u003c\/li\u003e\n    \u003cli\u003eTemperature-related fault codes or intermittent shutdowns (after confirming proper flow)\u003c\/li\u003e\n    \u003cli\u003eCorroded sensor body or damaged wiring\/connector\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eKey Features\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eOEM Hayward replacement for correct signal compatibility and fit\u003c\/li\u003e\n    \u003cli\u003eRestores accurate water temperature sensing for stable heater operation\u003c\/li\u003e\n    \u003cli\u003eDesigned for in-ground pool heater applications\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eSpecs (Quick Reference)\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003ePart Number: \u003cstrong\u003eFDXLTER1931\u003c\/strong\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePart Type: \u003cstrong\u003eHeater Parts\u003c\/strong\u003e (Thermistor \/ Temperature Sensor)\u003c\/li\u003e\n    \u003cli\u003ePool Type: \u003cstrong\u003eIn-Ground\u003c\/strong\u003e\n\u003c\/li\u003e\n    \u003cli\u003eReplacement Part Warranty: \u003cstrong\u003e1-Year (Parts Only)\u003c\/strong\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eInstallation Notes\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eTurn off power\u003c\/strong\u003e to the heater at the breaker before servicing.\u003c\/li\u003e\n    \u003cli\u003eInspect the connector and wiring harness for corrosion or loose pins before installing the new sensor.\u003c\/li\u003e\n    \u003cli\u003eIf the heater still shows temperature issues after replacement, inspect water flow, bypass settings, and the control board input.\u003c\/li\u003e\n    \u003cli\u003eInstallation should be performed by a qualified technician.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eRelated Products\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=FDXLTER1931\"\u003eHayward FDXLTER1931 Thermistor (search)\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=FDXLWPS1930\"\u003eHayward FDXLWPS1930 Water Pressure Switch (FD Heaters) (search)\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=Hayward%20H-Series%20FD%20heater%20parts\"\u003eHayward Universal H-Series FD Heater Parts (search)\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=pool%20heater%20igniter%20hayward%20FD\"\u003eHayward FD Heater Igniters (search)\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=pool%20heater%20flame%20sensor%20hayward%20FD\"\u003eHayward FD Heater Flame Sensors (search)\u003c\/a\u003e\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr\u003e\n\n  \u003ch3\u003eMaintenance Tips\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eKeep the filter clean and valves fully open—flow issues can cause erratic heater behavior that looks like a sensor problem.\u003c\/li\u003e\n    \u003cli\u003eMaintain balanced water chemistry to reduce scale inside the heater, which can affect temperature control and efficiency.\u003c\/li\u003e\n    \u003cli\u003eInspect heater wiring connections seasonally for corrosion or loose terminals, especially in humid or coastal environments.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n\u003c\/div\u003e","brand":"Hayward","offers":[{"title":"Default Title","offer_id":52589938442556,"sku":"FDXLTER1931","price":44.39,"currency_code":"USD","in_stock":true}],"url":"https:\/\/aquapoolsupply.com\/products\/haywardhseriesfdheaterthermistorfdxlter1931hppfdxlter1931","provider":"Aqua Pool Supply","version":"1.0","type":"link"}