What are the specs for this Transformer?

The correct replacement for Tempstar model T8MPL100J20B1 — 120V to 24V Control | 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 T8MPL100J20B1 — 120V to 24V Control | 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 T8MPL100J20B1 — 120V to 24V Control | Ships Today

Name: Tempstar 40VA Transformer for T8MPL100J20B1 — 120V to 24V Control | Ships Today
Brand: Tempstar
SKU: 1172810-GEN
Price: 29.00 USD
Availability: InStock

SKU: 1172810-GEN Brand: Tempstar

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Overview

This OEM control transformer (part 1172810, TRANS 115>24 40VA) steps 120V line voltage down to 24V to power the thermostat, control board, gas valve, and low-voltage relays on the Tempstar T8MPL100J20B1 gas furnace. Rated at 40VA, it delivers enough current to drive the full 24V control circuit. A failed transformer means a completely dead furnace — no thermostat response, no control board activity, and no ignition sequence.

Specifications

Spec	Value
Part Number	1172810
Type	Control transformer
Brand	Tempstar (ICP / Heil family)
Rating	40VA
Primary Voltage	120V
Secondary Voltage	24V
Fitment	OEM direct replacement

Compatibility

Built for the Tempstar T8MPL100J20B1 modulating gas furnace and shared ICP/Heil/Comfortmaker control assemblies using a 120V-to-24V 40VA transformer. Verify primary voltage and VA rating against your unit before ordering.

Installation Guide

Safety First — Disconnect power at the furnace switch and breaker; verify zero voltage with a multimeter.
Access — Remove the control compartment panel to reach the transformer and control board.
Document — Photograph the primary (line) and secondary (24V) lead connections before disconnecting.
Remove — Disconnect the leads, remove the mounting screws, and take out the failed transformer.
Install — Mount the new transformer, then reconnect primary and secondary leads exactly per your photo.
Test — Restore power and confirm 24V across the secondary, plus a normal thermostat and ignition response.

Signs You Need a Replacement

Furnace is completely dead — no thermostat or control board response.
No 24V measured across the secondary terminals.
Burnt smell, scorched windings, or a tripped/blown low-voltage fuse.
Repeated control-circuit fuse failures after a short is cleared.

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 T8...

$29.00

Frequently Asked Questions

Does this Transformer fit my Tempstar T8MPL100J20B1 — 120V to 24V Control | Ships Today?

Yes. This is the factory-specified OEM transformer for the Tempstar T8MPL100J20B1 — 120V to 24V Control | 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 T8MPL100J20B1 — 120V to 24V Control | 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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