{"product_id":"tempstar-40va-transformer-for-thb09k25rta-208-240v-to-24v-ships-today","title":"Tempstar 40VA Transformer for THB09K25RTA — 208\/240V to 24V | Ships Today","description":"\u003ch3\u003eOverview\u003c\/h3\u003e\n\u003cp\u003eThis OEM control transformer and relay set powers the 24V control circuit on the Tempstar THB09K25RTA PTAC heat pump. The transformer (OEM 1056899) steps 208\/240V line voltage down to 24V at 40VA to drive the thermostat, relays, and reversing valve. The kit also includes the companion 24V relays (OEM 1053004 single relay and OEM 1060940 DPST relay) that switch the compressor and fan circuits. When the transformer fails — usually from a short, overload, or age — the entire unit goes dead even though line power is present. Replacing the 40VA transformer and worn relays restores reliable low-voltage control.\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 Numbers\u003c\/td\u003e\n\u003ctd\u003e1056899 (TRANS 208\/240→24 40VA), 1053004 (RELAY 24V), 1060940 (RELAY 24V DPST)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eStep-Down Control Transformer + Relays\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\u003e208\/240V\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\u003eTHB09K25RTA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cp\u003eDirect OEM replacement for the Tempstar THB09K25RTA PTAC heat pump. The 40VA 208\/240-to-24V transformer and matching 24V relays are shared across the Heil\/ICP THB09K25 PTAC family. Verify your existing OEM part numbers 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 unit and breaker; verify zero voltage with a multimeter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccess\u003c\/strong\u003e — Remove the front grille and service panel to reach the control box.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDocument\u003c\/strong\u003e — Photo all primary and secondary wiring before disconnecting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRemove\u003c\/strong\u003e — Disconnect the transformer leads and relay terminals, then unmount the old components.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstall\u003c\/strong\u003e — Mount the new transformer and relays, reconnect 208\/240V primary and 24V secondary per your photo.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest\u003c\/strong\u003e — Restore power and confirm 24V at the secondary and proper relay operation.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eSigns You Need a Replacement\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eUnit is completely dead with line voltage present.\u003c\/li\u003e\n\u003cli\u003eNo 24V reading at the transformer secondary.\u003c\/li\u003e\n\u003cli\u003eRepeated control-fuse or breaker trips.\u003c\/li\u003e\n\u003cli\u003eRelays buzz, chatter, or fail to pull in the compressor\/fan.\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":63021638713715,"sku":"1053004-GEN","price":38.0,"currency_code":"USD","in_stock":true},{"title":"OEM","offer_id":63048412463475,"sku":"1053004","price":49.4,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-transformer-control-1053004_8fff0439-bb77-4f05-a39b-6ec74292da98.jpg?v=1782958595","url":"https:\/\/nationalhvacparts.com\/products\/tempstar-40va-transformer-for-thb09k25rta-208-240v-to-24v-ships-today","provider":"National HVAC Parts","version":"1.0","type":"link"}