What are the specs for this Transformer?

The correct replacement for Lennox model OEM Lennox Transformer Kit — 17W56 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 Lennox equipment which lists the model number OEM Lennox Transformer Kit — 17W56.

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OEM Lennox Transformer Kit — 17W56

Name: OEM Lennox Transformer Kit — 17W56
Brand: Lennox
SKU: LNX-17W56
Price: 29.95 USD
Availability: InStock

SKU: LNX-17W56 Brand: Lennox

$29.95 $39.95

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The genuine OEM Lennox 17W56 transformer kit steps down incoming line voltage (typically 120V or 240V) to the 24V low-voltage control power your furnace, thermostat, and control board rely on. Nearly every low-voltage function in the system — from the thermostat call for heat to the gas valve and relays — depends on clean, stable output from this transformer. The kit includes the mounting and wiring components for a straightforward replacement in compatible Lennox equipment.

Common failure symptoms: When the 17W56 transformer fails, the furnace and thermostat typically go completely dead with no 24V control power. You may find a blank thermostat display, no response to a heat call, or a repeatedly blown low-voltage fuse. Transformers commonly fail from a short in the control wiring, a stuck contactor, or simple age-related winding breakdown.

Why OEM matters: The Lennox 17W56 is matched to your system's VA load rating and primary voltage. An undersized or mismatched aftermarket transformer can overheat, deliver unstable voltage, or fail prematurely under load. Choosing the OEM part guarantees the correct capacity and mounting for dependable control power.

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

OEM Lennox Transformer Kit — 17W56

$29.95

Frequently Asked Questions

Does this Transformer fit my Lennox OEM Lennox Transformer Kit — 17W56?

Yes. This is the factory-specified OEM transformer for the Lennox OEM Lennox Transformer Kit — 17W56. 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 Lennox OEM Lennox Transformer Kit — 17W56?

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 Lennox 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 Lennox 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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OEM Lennox Transformer Kit — 17W56

Shipping Information

Return Policy

Frequently Asked Questions