What are the specs for this Transformer?

The correct replacement for Tempstar model THB09K25RTA — 208/240V to 24V | Ships Today is this exact part. It is the factory-specified replacement with exact OEM specifications. Using a part with different specifications can cause equipment damage or void your warranty. You can verify this by checking the data plate on your Tempstar equipment which lists the model number THB09K25RTA — 208/240V to 24V | Ships Today.

Is this transformer compatible with Bryant or Payne systems too?

Many Tempstar parts are cross-compatible with Bryant and Payne systems since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across multiple brand labels with different model numbers. To verify cross-compatibility, check your Bryant or Payne equipment service manual for cross-compatible part numbers, or contact info@nationalhvacparts.com with your model number for confirmation.

Tempstar

Tempstar 40VA Transformer for THB09K25RTA — 208/240V to 24V | Ships Today

Name: Tempstar 40VA Transformer for THB09K25RTA — 208/240V to 24V | Ships Today
Brand: Tempstar
SKU: 1053004-GEN
Price: 38.00 USD
Availability: InStock

SKU: 1053004-GEN Brand: Tempstar

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Overview

This 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.

Specifications

Spec	Value
OEM Part Numbers	1056899 (TRANS 208/240→24 40VA), 1053004 (RELAY 24V), 1060940 (RELAY 24V DPST)
Type	Step-Down Control Transformer + Relays
Brand	Tempstar
Rating	40 VA
Primary Voltage	208/240V
Secondary Voltage	24V
Fits Model	THB09K25RTA

Compatibility

Direct 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.

Installation Guide

Safety First — Disconnect power at the unit and breaker; verify zero voltage with a multimeter.
Access — Remove the front grille and service panel to reach the control box.
Document — Photo all primary and secondary wiring before disconnecting.
Remove — Disconnect the transformer leads and relay terminals, then unmount the old components.
Install — Mount the new transformer and relays, reconnect 208/240V primary and 24V secondary per your photo.
Test — Restore power and confirm 24V at the secondary and proper relay operation.

Signs You Need a Replacement

Unit is completely dead with line voltage present.
No 24V reading at the transformer secondary.
Repeated control-fuse or breaker trips.
Relays buzz, chatter, or fail to pull in the compressor/fan.

Shipping & Returns

Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.

Shipping Information

Orders placed before 3PM CST ship same business day
Standard delivery: 2-5 business days
Express shipping available at checkout
Free shipping on orders over $75
Tracking number emailed upon shipment

Return Policy

30-day returns on unused parts in original packaging
Electrical parts (capacitors, contactors, control boards) are final sale once installed
Email info@nationalhvacparts.com to initiate a return
Refunds processed within 5-7 business days

Tempstar 40VA Transformer for TH...

$38.00

Frequently Asked Questions

Does this Transformer fit my Tempstar THB09K25RTA — 208/240V to 24V | Ships Today?

Yes. This is the factory-specified OEM transformer for the Tempstar THB09K25RTA — 208/240V to 24V | Ships Today. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.

How do I replace the transformer on my Tempstar THB09K25RTA — 208/240V to 24V | Ships Today?

Difficulty: Medium (30–45 min)
Step 1: Turn off breaker. Step 2: Photo wiring connections. Step 3: Disconnect wires from old transformer. Step 4: Remove mounting hardware. Step 5: Install new transformer, reconnect wires matching voltage ratings. Step 6: Verify 24V output with multimeter.

My thermostat has no power. What failed?

Thermostat with no display = failed 24V transformer (or blown control board fuse). Check the 3A/5A fuse on the control board first ($1–$5 fix). If fuse is good but no 24V output from transformer, replace transformer.

Is this transformer compatible with Bryant or Payne too?

Many Tempstar parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.

Should I use OEM or aftermarket for my Tempstar transformer?

OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.

How fast does National HVAC Parts ship?

Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.

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