{"product_id":"tempstar-40va-transformer-for-t8mpt100f14b1-115v-to-24v-control-power-ships-today","title":"Tempstar 40VA Transformer for T8MPT100F14B1 — 115V to 24V Control Power | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis OEM control transformer (Part #1172810) provides the 24-volt power that operates the entire control circuit of your Tempstar T8MPT100F14B1 furnace. It converts 115V line voltage down to 24V at 40VA, feeding the control board, thermostat, two-stage gas valve, and blower relays. When the transformer fails, the low-voltage side of the furnace goes completely dead: the thermostat stops responding, the board loses power, and no heat call can be initiated. Transformers fail from a shorted winding, an overloaded 24V circuit, a power surge, or insulation breakdown over time. Watch for a blank thermostat, a dead control board, a low-voltage fuse that blows on power-up, or a faint electrical-burn odor at the furnace. This is the exact 40VA OEM replacement for the F14B1.\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\u003eStep-Down Control 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\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\u003e40 VA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFit\u003c\/td\u003e\n\u003ctd\u003eOEM Replacement\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cp\u003eDesigned for the Tempstar T8MPT100F14B1 gas furnace. The same 115V-to-24V 40VA transformer is used across many ICP-family furnaces (Tempstar, Heil, Comfortmaker, Arcoaire) of this generation. Confirm the original part number and the primary\/secondary voltage printed on 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 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) wiring before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the leads and unbolt the 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 to line voltage and secondary to the 24V circuit exactly per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power, confirm 24V across the secondary, and verify the board powers up and the thermostat calls 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\u003eThermostat and control board are completely unpowered.\u003c\/li\u003e\n\u003cli\u003eFurnace will not begin a heat cycle.\u003c\/li\u003e\n\u003cli\u003eLow-voltage fuse blows immediately on power-up.\u003c\/li\u003e\n\u003cli\u003eBurning smell or visible discoloration on the transformer.\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":63021721321843,"sku":"1172810-GEN","price":32.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048405352819,"sku":"1172810","price":41.6,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1172810_39cd1d8b-4eda-412b-9df2-d93efe6492e6.jpg?v=1782958326","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-t8mpt100f14b1-115v-to-24v-control-power-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}