{"product_id":"tempstar-transformer-for-t8mpn125j20a1-115v-to-24v-40va-ships-today","title":"Tempstar Transformer for T8MPN125J20A1 — 115V to 24V 40VA | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis OEM control transformer (part number 1012722, TRANS 115\u0026gt;24 40VA) steps 115V line voltage down to 24V to power the low-voltage control circuit in your Tempstar T8MPN125J20A1 gas furnace. Rated at 40VA, it feeds the thermostat, gas valve, igniter control, and relays. A bad transformer is a leading cause of a furnace that won't respond to the thermostat at all. Watch for a dead control board, no 24V at the thermostat terminals, a repeatedly blown low-voltage fuse, or a transformer that buzzes or smells burnt. Since it powers the entire 24V load, always inspect for a shorted gas valve, igniter circuit, or control wire before installing a replacement so the new unit doesn't fail the same way.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\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\u003ePart 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\u003e40VA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cp\u003eDirect OEM fit for the Tempstar T8MPN125J20A1 gas furnace and other ICP\/Heil\/Tempstar\/Comfortmaker N9\/T8 series furnaces using the same 115V-to-24V 40VA control transformer. Confirm the part number on your existing transformer before ordering.\u003c\/p\u003e\n\n\u003ch3\u003eInstallation Guide\u003c\/h3\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafety First\u003c\/strong\u003e — Disconnect power at the furnace switch and breaker, and verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the furnace blower\/control compartment service panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph all primary and secondary wire connections before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the 115V primary leads and the 24V secondary leads, then unbolt the transformer from its bracket.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer and reconnect the primary and secondary wiring exactly per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and verify 24V across the secondary terminals and proper furnace response to the thermostat.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eNo 24V at the thermostat or control board\u003c\/li\u003e\n\u003cli\u003eFurnace completely unresponsive to thermostat calls\u003c\/li\u003e\n\u003cli\u003eBuzzing, humming, or burnt smell from the transformer\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown low-voltage fuse after wiring is verified good\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eShipping \u0026amp; Returns\u003c\/h3\u003e\n\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":63021762412915,"sku":"1012722-GEN","price":33.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048490254707,"sku":"1012722","price":42.9,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1012722_c70d682b-b25e-4983-8a69-1b324d681ed2.jpg?v=1782961428","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-transformer-for-t8mpn125j20a1-115v-to-24v-40va-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}