{"product_id":"tempstar-40va-transformer-for-t8mpn100f14b2-furnace-115v-to-24v-ships-today","title":"Tempstar 40VA Transformer for T8MPN100F14B2 Furnace — 115V to 24V | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\u003cp\u003eThis OEM control transformer (part number 1172810, \"TRANS 115\u0026gt;24 40VA\") supplies the 24-volt control power for the Tempstar T8MPN100F14B2 gas furnace. It steps 115V line voltage down to a 24V secondary and is rated at 40VA — enough capacity to power the control board, thermostat, gas valve, and ignition circuit. When this transformer fails, the entire low-voltage control system loses power: the thermostat goes dark, there is no call for heat, and the furnace will not start. Transformers most often fail from a shorted secondary (frequently caused by a pinched or grounded thermostat wire) or from a chronically overloaded control circuit. Replacing it restores 24V power and normal furnace operation.\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\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\u003ctr\u003e\n\u003ctd\u003eFits Model\u003c\/td\u003e\n\u003ctd\u003eT8MPN100F14B2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch3\u003eCompatibility\u003c\/h3\u003e\u003cp\u003eDesigned for the Tempstar T8MPN100F14B2 furnace and interchangeable across ICP-family furnaces (Heil, Comfortmaker, Arcoaire) that use the same 115V-to-24V 40VA control transformer. Verify the primary\/secondary voltages and VA rating against your existing unit before installing.\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 control compartment service panel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photograph the primary and secondary wire connections before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Label and disconnect the 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 and reconnect the primary (line) and secondary (24V) leads per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, confirm 24V at the secondary with a meter, and verify the thermostat powers up and the furnace responds to a heat call.\u003c\/li\u003e\n\u003c\/ol\u003e\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eBlank or dead thermostat with the furnace powered\u003c\/li\u003e\n\u003cli\u003eNo 24V control voltage measured at the board\u003c\/li\u003e\n\u003cli\u003eFurnace does not respond to a heat call\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown control fuse or burnt transformer windings\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":63021766934899,"sku":"1172810-GEN","price":24.95,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048404566387,"sku":"1172810","price":32.44,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_af8b6495-e280-48dc-99f3-a6d4b0fc7474.jpg?v=1782958296","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-t8mpn100f14b2-furnace-115v-to-24v-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}