{"product_id":"weil-mclain-591-391-818","title":"Weil McLain 591-391-818 Wiring Harness","description":"\u003cp\u003eThe \u003cstrong\u003eWeil McLain 591-391-818 Control Module to Circulator Wiring Harness\u003c\/strong\u003e is the factory \u003cstrong\u003eharness\u003c\/strong\u003e that connects a \u003cstrong\u003eboiler\u003c\/strong\u003e's \u003cstrong\u003econtrol module\u003c\/strong\u003e to its \u003cstrong\u003ecirculator\u003c\/strong\u003e. \u003cstrong\u003eWeil McLain\u003c\/strong\u003e's \u003cstrong\u003eGV Series 1 and 2\u003c\/strong\u003e parts list includes \u003cstrong\u003e591-391-818\u003c\/strong\u003e, so it is a manufacturer-listed part for those gas boilers and not a generic extension lead. The \u003cstrong\u003eharness\u003c\/strong\u003e is terminated with a \u003cstrong\u003econnector\u003c\/strong\u003e, and the product photo shows it laid out next to rulers for scale.\u003c\/p\u003e\n\n\u003cp\u003eWhen a \u003cstrong\u003ecirculator\u003c\/strong\u003e \u003cstrong\u003eharness\u003c\/strong\u003e is damaged, the symptoms are often intermittent. A \u003cstrong\u003ecirculator\u003c\/strong\u003e that does not start on a call for heat, a pump that runs when it should not, or a \u003cstrong\u003econtrol module\u003c\/strong\u003e that appears healthy while the \u003cstrong\u003ecirculator\u003c\/strong\u003e never responds can all trace back to a cracked insulation jacket, a heat-damaged plug or a corroded terminal. Replacing the whole \u003cstrong\u003eharness\u003c\/strong\u003e with the \u003cstrong\u003e591-391-818\u003c\/strong\u003e restores the original connection between the \u003cstrong\u003econtrol module\u003c\/strong\u003e and the \u003cstrong\u003ecirculator\u003c\/strong\u003e and avoids splicing wire in a spot where heat and vibration are constant.\u003c\/p\u003e\n\n\u003cp\u003eBefore you order, compare the \u003cstrong\u003econnector\u003c\/strong\u003e on the old \u003cstrong\u003eharness\u003c\/strong\u003e with the product photo and confirm the \u003cstrong\u003eboiler\u003c\/strong\u003e is a \u003cstrong\u003eGV Series 1\u003c\/strong\u003e or 2. Other \u003cstrong\u003eWeil McLain\u003c\/strong\u003e harnesses carry different part numbers and are not interchangeable, so the part number on the old \u003cstrong\u003eharness\u003c\/strong\u003e or the \u003cstrong\u003eboiler\u003c\/strong\u003e model and serial number is the quickest way to be sure.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eKey Benefits\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eListed for GV Series 1 and 2:\u003c\/strong\u003e \u003cstrong\u003e591-391-818\u003c\/strong\u003e appears in the \u003cstrong\u003eWeil McLain\u003c\/strong\u003e \u003cstrong\u003eGV Series 1 and 2\u003c\/strong\u003e parts list, so it is a manufacturer-specified \u003cstrong\u003eharness\u003c\/strong\u003e for those boilers.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eComplete Harness Replacement:\u003c\/strong\u003e Replaces the whole run from the \u003cstrong\u003econtrol module\u003c\/strong\u003e to the \u003cstrong\u003ecirculator\u003c\/strong\u003e instead of a splice repair in a hot, vibrating location.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eConnector Terminated:\u003c\/strong\u003e Arrives with its \u003cstrong\u003econnector\u003c\/strong\u003e in place, so the module and \u003cstrong\u003ecirculator\u003c\/strong\u003e connections plug back in the way they were built.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eClear Part Number Match:\u003c\/strong\u003e One manufacturer number, \u003cstrong\u003e591-391-818\u003c\/strong\u003e, to match against the old \u003cstrong\u003eharness\u003c\/strong\u003e or the parts list.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eCommon Questions\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eWhat does the 591-391-818 connect?\u003c\/strong\u003e It is the \u003cstrong\u003econtrol module\u003c\/strong\u003e to \u003cstrong\u003ecirculator\u003c\/strong\u003e \u003cstrong\u003ewiring harness\u003c\/strong\u003e for \u003cstrong\u003eWeil McLain\u003c\/strong\u003e gas boilers listed in the \u003cstrong\u003eGV Series 1 and 2\u003c\/strong\u003e parts list.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eDoes it fit every Weil McLain GV boiler?\u003c\/strong\u003e No. Other \u003cstrong\u003eGV\u003c\/strong\u003e series use different \u003cstrong\u003eharness\u003c\/strong\u003e numbers. The \u003cstrong\u003e591-391-818\u003c\/strong\u003e is shown in the \u003cstrong\u003eGV Series 1 and 2\u003c\/strong\u003e parts list, and our team can confirm fit if you send the \u003cstrong\u003eboiler\u003c\/strong\u003e model and serial number.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCan I repair the old harness instead?\u003c\/strong\u003e A damaged jacket or burned plug is better handled by replacing the \u003cstrong\u003eharness\u003c\/strong\u003e. Splices and field-made repairs sit in a hot area and tend to fail again.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eDisclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.\u003c\/p\u003e\n","brand":"Weil McLain","offers":[{"title":"Default Title","offer_id":68008918319282,"sku":"591-391-818","price":38.88,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1838\/2375\/files\/591-391-818.jpg?v=1794513173","url":"https:\/\/www.gsistore.com\/products\/weil-mclain-591-391-818","provider":"GSIstore","version":"1.0","type":"link"}