Guide · Updated 2026-10-30
Michigan Limited Heating Service exam guide
Practice for the Michigan Limited Heating Service exam: combustion, ignition systems, controls, furnaces, boilers, and venting.
The format
- 55 questions
- 60 minutes
- 75% to pass
- Closed book no references
- Exam fee: $50 (PSI).
Test-day rules
- Computer-based at PSI test centers, after LARA approves your application.
- Closed book: no references allowed.
- Questions on PA 407 (the Skilled Trades Regulation Act) and PA 230 appear on every classification exam.
What’s on it
PSI lists the content areas but not how many questions come from each. Our practice uses these estimated weights:
| Topic | Our estimated weight | In our mock | Bank |
|---|---|---|---|
Michigan law and license scope (PA 407 Article 8)
| 9% | 5 | 8 |
Combustion, fuels, and burners
| 16% | 9 | 12 |
Ignition systems and flame safeguards
| 16% | 9 | 12 |
Controls, electrical, and troubleshooting
| 18% | 10 | 13 |
Furnaces, unit heaters, and radiant heaters
| 14% | 8 | 10 |
Sectional and steam boilers
| 12% | 6 | 9 |
Venting, draft, combustion air, and carbon monoxide
| 15% | 8 | 11 |
A study plan
- Know combustion basics and flue gas analysis by heart. It’s closed book.
- Review ignition systems and flame safeguards.
- Trace control sequences for furnaces and boilers.
- Learn venting categories and common vent problems.
- Take timed mocks.
Try 10 free Limited Heating Service questions Limited Heating Service practice page
Sources: PSI Candidate Information Bulletin 5421 (mechanical, effective Aug 20, 2026) · LARA mechanical exam reference materials (PDF). Checked October 30, 2026. Rules and fees change, so confirm with LARA and PSI.
FAQ
How many questions are on the Limited Heating Service exam?
PSI’s bulletin lists 55 questions in 60 minutes with 75% to pass. It is closed book.
What does it cost?
PSI lists $50.
MI Trade Prep is an independent study tool, not affiliated with LARA or PSI.