{"product_id":"alton-thermofor-roof-vent-opener-piston-replacement","title":"Alton | Thermofor Roof Vent Opener Piston Replacement","description":"\u003cp\u003eThe Thermofor Long Piston Replacement is a direct replacement cylinder designed for Thermofor automatic roof vent openers used in Alton greenhouses. If your current opener is no longer responding properly to temperature changes, replacing the piston is a simple way to restore reliable, automatic ventilation.\u003c\/p\u003e\n\n\u003cp\u003eThis heat-sensitive cylinder contains a wax core that expands as temperatures rise and contracts as they cool, driving the vent to open and close naturally. It helps maintain a stable growing environment without electricity or manual adjustment.\u003c\/p\u003e\n\n\u003ch6\u003eKEY FEATURES\u003c\/h6\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDesigned for Thermofor openers:\u003c\/strong\u003e Compatible with Thermofor roof vent systems used in Alton greenhouses.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRestores automatic ventilation:\u003c\/strong\u003e Brings your vent opener back to proper working condition.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHeat-powered operation:\u003c\/strong\u003e No electricity or batteries required.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReplacement cylinder only:\u003c\/strong\u003e No fittings or hardware included.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch6\u003eSPECIFICATIONS\u003c\/h6\u003e\n\u003cdiv style=\"background-color: #f4f8f2; padding: 18px; border-radius: 12px; margin: 14px 0;\"\u003e\n  \u003cp\u003e\u003cstrong\u003ePRODUCT TYPE:\u003c\/strong\u003e Replacement piston cylinder\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eCOMPATIBILITY:\u003c\/strong\u003e Thermofor roof vent openers only\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eOVERALL LENGTH:\u003c\/strong\u003e 8 inches\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eMETRIC LENGTH:\u003c\/strong\u003e 200 mm\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eINCLUDED:\u003c\/strong\u003e Cylinder only (no fittings)\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch6\u003eINSTALLATION GUIDE\u003c\/h6\u003e\n\u003cp\u003eFor proper installation and accurate operation, the piston must be cooled before fitting. Place the cylinder in a refrigerator for approximately 30 minutes. This allows the wax inside to contract so the piston rod can be fully depressed.\u003c\/p\u003e\n\n\u003cp\u003eOnce cooled, press the piston rod firmly against a hard surface until it retracts into the cylinder. Install the unit with the vent arms in the closed position to ensure correct alignment with the vent and mounting points.\u003c\/p\u003e\n\n\u003cp\u003eSkipping the cooling step may prevent the unit from being set correctly.\u003c\/p\u003e\n\n\u003ch6\u003eMAINTENANCE AND CARE\u003c\/h6\u003e\n\u003cp\u003eKeep the piston clean and free from debris to ensure smooth movement. Periodically check alignment and mounting points to maintain consistent vent performance.\u003c\/p\u003e\n\n\u003ch6\u003eFREQUENTLY ASKED QUESTIONS\u003c\/h6\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat does the piston do in a greenhouse vent opener?\u003c\/strong\u003e\u003cbr\u003e\nThe piston contains a wax-filled core that expands with heat, pushing the vent open. As temperatures drop, it contracts and closes the vent.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eDo I need electricity for this to work?\u003c\/strong\u003e\u003cbr\u003e\nNo. The piston operates entirely through heat expansion, so no power source is required.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhy do I need to refrigerate the piston before installation?\u003c\/strong\u003e\u003cbr\u003e\nCooling contracts the wax inside, allowing the piston to reset properly so it can be installed and calibrated accurately.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill this fit other vent opener brands?\u003c\/strong\u003e\u003cbr\u003e\nNo. This replacement piston is designed specifically for Thermofor roof vent openers and may not be compatible with other brands.\u003c\/p\u003e","brand":"Alton","offers":[{"title":"Default Title","offer_id":47355256438933,"sku":"ALTTHCY0002L","price":45.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0097\/9959\/8140\/files\/Thermofor-Autovent-piston.jpg?v=1778818527","url":"https:\/\/mygreenhousestore.com\/products\/alton-thermofor-roof-vent-opener-piston-replacement","provider":"MyGreenhouseStore.com","version":"1.0","type":"link"}