{"product_id":"tempstar-transformer-for-t8mpn075b12b1-40va-115v-to-24v-ships-today","title":"Tempstar Transformer for T8MPN075B12B1 — 40VA 115V to 24V | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis is a genuine OEM 40VA control transformer (part number 1172810) for the Tempstar T8MPN075B12B1 gas furnace. The transformer steps down incoming 115V line voltage to the 24V low-voltage control circuit that powers the thermostat, gas valve, igniter circuit, and control board relays. A 40VA rating provides the amperage headroom needed to drive multiple 24V loads simultaneously. When a transformer fails — typically from a shorted secondary, an overloaded control circuit, or simple age — the entire furnace goes dead: no thermostat response, no ignition sequence, and no blower. Replacing the transformer with the correct OEM part restores reliable control power without guesswork on wiring or VA sizing.\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\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003e1172810\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eControl 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\u003eRating\u003c\/td\u003e\n\u003ctd\u003e40 VA\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\u003eFitment\u003c\/td\u003e\n\u003ctd\u003eOEM\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 transformer for the Tempstar T8MPN075B12B1 furnace and used across related ICP\/Heil\/Tempstar single-stage gas furnace platforms that share the same 40VA, 115-to-24V control architecture. Always verify the printed part number on your existing transformer 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 at the transformer terminals.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the furnace control\/blower compartment service panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph all primary (line) and secondary (24V) wire connections before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the primary and secondary leads, then unbolt the transformer from its mounting bracket.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer, reconnect the 115V primary and 24V secondary leads per your photo, and confirm tight terminals.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, measure 24V across the secondary, and run a full heating cycle to confirm ignition and blower operation.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eFurnace is completely unresponsive — no thermostat display or call for heat.\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown low-voltage fuse on the control board.\u003c\/li\u003e\n\u003cli\u003eNo measurable 24V across the transformer secondary while line voltage is present.\u003c\/li\u003e\n\u003cli\u003eBuzzing, scorched smell, or visible discoloration on the transformer body.\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":63021776011635,"sku":"1172810-GEN","price":24.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048490090867,"sku":"1172810","price":31.2,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_376c19ae-6d0d-4ae4-a669-b97c8c6e0d51.jpg?v=1782961421","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-transformer-for-t8mpn075b12b1-40va-115v-to-24v-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}