{"product_id":"tempstar-transformer-115v-to-24v-40va-for-t8dnl050b12a1-ships-today","title":"Tempstar Transformer 115V to 24V 40VA for T8DNL050B12A1 — Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is a genuine OEM control transformer (part number 1012722) for the Tempstar T8DNL050B12A1 furnace. It steps line voltage down from 115 volts on the primary to 24 volts on the secondary at 40 VA, supplying the low-voltage control power that runs the thermostat circuit, gas valve, ignition control, and relays. Without a working transformer the entire 24V control side goes dead: the thermostat screen may blank, the system will not respond to a call for heat or cool, and the unit appears completely unpowered even though line voltage is present. A transformer typically fails from an internal short, an open winding caused by a shorted control component downstream, or simple age-related insulation breakdown. Replacing it with the correct 40 VA OEM unit restores reliable control power without overloading the circuit.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpec\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eOEM Part Number\u003c\/td\u003e\n\u003ctd\u003e1012722\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eStep-Down Control Transformer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eTempstar\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrimary Voltage\u003c\/td\u003e\n\u003ctd\u003e115V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecondary Voltage\u003c\/td\u003e\n\u003ctd\u003e24V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRating\u003c\/td\u003e\n\u003ctd\u003e40 VA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFits Model\u003c\/td\u003e\n\u003ctd\u003eT8DNL050B12A1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eDesigned as the factory-spec control transformer for the Tempstar T8DNL050B12A1 and shared platforms across the ICP \/ Heil family that use the same 115V-to-24V 40VA assembly. Always confirm the existing part number before ordering.\u003c\/p\u003e\u003ch3\u003eInstallation Guide\u003c\/h3\u003e\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafety First\u003c\/strong\u003e — Disconnect power at the furnace switch and breaker, then verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the furnace control\/blower service panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph every primary and secondary wire connection before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the primary (line) and secondary (24V) leads, then unbolt or unclip the old transformer from the panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer, then reconnect primary and secondary leads exactly per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24V across the secondary terminals and normal system operation.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eBlank thermostat or no 24V control power\u003c\/li\u003e\n\u003cli\u003eSystem will not respond to heat or cool calls despite line voltage present\u003c\/li\u003e\n\u003cli\u003eMeasured secondary voltage is zero or well below 24V\u003c\/li\u003e\n\u003cli\u003eBurnt smell, scorched casing, or a repeatedly blown low-voltage fuse\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eShipping \u0026amp; Returns\u003c\/h3\u003e\u003cp\u003eShips same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.\u003c\/p\u003e","brand":"Tempstar","offers":[{"title":"Direct Replacement","offer_id":63021780992371,"sku":"1012722-GEN","price":29.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048489894259,"sku":"1012722","price":37.7,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1012722_60809f33-a80c-472b-97fc-8d646aa83a9c.jpg?v=1782961412","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-transformer-115v-to-24v-40va-for-t8dnl050b12a1-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}