What are the specs for this Transformer?

The correct replacement for Tempstar model T8MPL100F20B1 — 115V 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 T8MPL100F20B1 — 115V 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 T8MPL100F20B1 — 115V to 24V | Ships Today

Name: Tempstar 40VA Transformer for T8MPL100F20B1 — 115V to 24V | Ships Today
Brand: Tempstar
SKU: 1172810-GEN
Price: 27.95 USD
Availability: InStock

SKU: 1172810-GEN Brand: Tempstar

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Overview

This genuine OEM 40VA control transformer (OEM Part #1172810) powers the 24V control circuit of the Tempstar T8MPL100F20B1 gas furnace. It steps line voltage of 115V down to 24V, supplying the thermostat, gas valve, ignition control board, and relays. A failed transformer is one of the most common causes of a completely dead furnace — no thermostat display, no ignition sequence, and no blower. Symptoms include a blown low-voltage fuse, a burnt smell at the control board, or zero volts measured across the secondary 'R' and 'C' terminals.

Specifications

Spec	Value
Part Number	1172810
Type	Step-Down Control Transformer
Brand	Tempstar (ICP / Heil)
Rating	40 VA
Primary Voltage	115V
Secondary Voltage	24V
Fit	OEM Replacement

Compatibility

Designed for the Tempstar T8MPL100F20B1 furnace and compatible ICP/Heil/Comfortmaker furnaces using a 40VA 115V-to-24V control transformer. Verify primary voltage tap and VA rating against the unit you are servicing.

Installation Guide

Safety First — Disconnect power at the service switch and verify zero voltage with a multimeter.
Access — Remove the furnace control-compartment service panel.
Document — Photograph every primary and secondary wire connection before disconnecting.
Remove — Label and disconnect the leads, then unbolt the failed transformer from its bracket.
Install — Mount the new transformer, reconnect primary (line) and secondary (24V) leads exactly per your photo.
Test — Restore power and confirm 24V across the secondary terminals and a normal call-for-heat sequence.

Signs You Need a Replacement

Furnace completely dead — no thermostat power
Repeatedly blown 3A low-voltage control fuse
Zero or low voltage measured on the 24V secondary
Burnt smell or discoloration at the transformer

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...

$27.95

Frequently Asked Questions

Does this Transformer fit my Tempstar T8MPL100F20B1 — 115V to 24V | Ships Today?

Yes. This is the factory-specified OEM transformer for the Tempstar T8MPL100F20B1 — 115V 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 T8MPL100F20B1 — 115V 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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