{"product_id":"tempstar-control-transformer-for-t8mpn100f20b1-40va-115v-to-24v-ships-today","title":"Tempstar Control Transformer for T8MPN100F20B1 — 40VA 115V to 24V | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis is the OEM 40VA control transformer (part number 1172810) for the Tempstar T8MPN100F20B1 gas furnace. The transformer steps incoming 115V line voltage down to the 24V control voltage that powers the thermostat, gas valve, ignition control, and relays. If the transformer fails, the entire low-voltage control circuit loses power — the furnace will not respond to a thermostat call for heat, and the control board may show no signs of life even though line power is present. A bad transformer is a leading cause of a furnace that appears completely dead. Common symptoms include a blank thermostat, a buzzing or humming transformer, a burnt smell in the control compartment, or a low-voltage fuse that blows again the moment it is replaced.\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\u003eOEM Part Number\u003c\/td\u003e\n\u003ctd\u003e1172810\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDescription\u003c\/td\u003e\n\u003ctd\u003eTRANS 115\u0026gt;24 40VA\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 (Heil \/ ICP family)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVA Rating\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\u003eFits Model\u003c\/td\u003e\n\u003ctd\u003eT8MPN100F20B1\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 as a direct OEM replacement for the Tempstar T8MPN100F20B1 furnace. The same 40VA 115V-to-24V transformer is used across many Tempstar, Heil, Comfortmaker, and ICP-built furnaces. Always confirm part number 1172810 against your existing transformer before installing.\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.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the furnace service panel to expose the control compartment.\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 — Disconnect the line-voltage primary leads and the 24V secondary leads, then unbolt the failed 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, confirm 24V at the secondary, and verify the furnace responds to 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\u003eBlank thermostat and no furnace response despite line power present\u003c\/li\u003e\n\u003cli\u003eRepeatedly blown low-voltage (3A) control fuse\u003c\/li\u003e\n\u003cli\u003eAudible buzzing, humming, or a burnt smell from the transformer\u003c\/li\u003e\n\u003cli\u003eNo measurable 24V at the secondary terminals\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":63021766738291,"sku":"1172810-GEN","price":28.95,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048437662067,"sku":"1172810","price":37.63,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_fa5e14ee-b8fb-40d7-a9f7-30dfbd7a2abc.jpg?v=1782959582","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-control-transformer-for-t8mpn100f20b1-40va-115v-to-24v-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}