{"product_id":"tempstar-40va-transformer-for-t8mpv125j20c1-115v-to-24v-ships-today","title":"Tempstar 40VA Transformer for T8MPV125J20C1 — 115V to 24V | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis is a genuine OEM control transformer (part number 1172810) for the Tempstar T8MPV125J20C1 gas furnace. It steps line voltage of 115V down to the 24V low-voltage control circuit that powers the thermostat, gas valve, igniter, and control board. Rated at 40VA, it supplies enough capacity to drive the furnace's full complement of 24V loads. When a transformer fails, the entire low-voltage control system goes dead: the thermostat screen may go blank, the furnace will not respond to a call for heat, and you will read 115V on the primary but little or no 24V on the secondary. A buzzing transformer, a tripped internal thermal fuse, or scorched windings are all signs the unit needs replacement.\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\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 (ICP \/ Heil)\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\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eGas Furnace Control Circuit\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cp\u003eEngineered for the Tempstar T8MPV125J20C1 furnace and shared across the ICP family of brands (Heil, Comfortmaker, Arcoaire, KeepRite) that use the same 40VA 115V-to-24V control platform. Always confirm the part number stamped 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, then verify zero voltage with a multimeter on both primary and secondary leads.\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 and secondary wire connections before disconnecting anything.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and disconnect the line-voltage primary leads and the 24V secondary leads, then unbolt the failed transformer from its mounting bracket.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer, reconnect primary and secondary leads exactly per your photo, and secure all wire nuts.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24V across the secondary terminals and normal furnace operation on a call for heat.\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 output on the secondary while 115V is present on the primary\u003c\/li\u003e\n\u003cli\u003eThermostat is dead or furnace ignores the heat call\u003c\/li\u003e\n\u003cli\u003eBuzzing, humming, or burnt smell from the transformer\u003c\/li\u003e\n\u003cli\u003eRepeated control-fuse blowing on the board\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":63021686653299,"sku":"1172810-GEN","price":29.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048406303091,"sku":"1172810","price":37.7,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_cbbaf6e9-2bfc-4acd-8471-6e73a098a886.jpg?v=1782958363","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-t8mpv125j20c1-115v-to-24v-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}