What are the specs for this Transformer?

The correct replacement for Tempstar model T4H548GKB100 — 40VA Control Transformer | 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 T4H548GKB100 — 40VA Control Transformer | 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 24V Transformer for T4H548GKB100 — 40VA Control Transformer | Ships Today

Name: Tempstar 24V Transformer for T4H548GKB100 — 40VA Control Transformer | Ships Today
Brand: Tempstar
SKU: 1172574-GEN
Price: 29.00 USD
Availability: InStock

SKU: 1172574-GEN Brand: Tempstar

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Overview

This OEM 24V control transformer for the Tempstar T4H548GKB100 steps line voltage down to the 24V needed to power the unit's low-voltage control circuit — the thermostat, contactor coil, reversing valve, and safety switches all rely on it. Rated at 40VA, it supplies enough current for the full control load. When a control transformer fails, the entire low-voltage circuit goes dead: the thermostat won't call, the contactor won't pull in, and the compressor and fan stay off even though high-voltage power is present. Transformers commonly fail from a shorted control wire, a shorted contactor coil, or age-related winding breakdown.

Note: The associated part numbers 1172574 and 1175622 reference reversing-valve coil/valve components on this model. Confirm the exact control-transformer part number against your unit before ordering.

Specifications

Spec	Value
Type	Step-Down Control Transformer
Brand	Tempstar
Secondary Voltage	24V
Rating	40VA
Application	Heat Pump Low-Voltage Control
Fitment	OEM Direct Replacement

Compatibility

Fits the Tempstar T4H548GKB100 and related ICP-family outdoor units (Heil, Comfortmaker) using a 24V/40VA control circuit. Verify primary voltage and VA rating against your existing transformer before installing.

Installation Guide

Safety First — Disconnect power at the disconnect and breaker, and verify zero voltage with a multimeter.
Access — Remove the electrical access panel to reach the transformer and control board.
Document — Photograph all primary and secondary leads before disconnecting.
Remove — Disconnect the leads, remove the mounting screws, and take out the failed transformer.
Install — Mount the new transformer, match primary leads to line voltage and secondary leads to the 24V circuit per your photos.
Test — Restore power and confirm 24V across the secondary and that the thermostat call energizes the contactor.

Signs You Need a Replacement

No 24V at the control board or thermostat terminals
Contactor won't pull in on a cooling/heating call
Repeatedly blown low-voltage fuse or burnt-smelling transformer
System has high voltage but no control-circuit operation

Shipping & Returns

Ships same day on orders placed before 3 PM CST. 30-day returns on unused parts. 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 24V Transformer for T4H...

$29.00

Frequently Asked Questions

Does this Transformer fit my Tempstar T4H548GKB100 — 40VA Control Transformer | Ships Today?

Yes. This is the factory-specified OEM transformer for the Tempstar T4H548GKB100 — 40VA Control Transformer | 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 T4H548GKB100 — 40VA Control Transformer | 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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