Code: 22🔥 Ruud Gas Furnace

Ruud / Rheem Furnace Code 22: Main Limit Open (Meaning, Causes, Fixes)

Reviewed 2026-10-25 · Based on 4 manufacturer & service sources

What the code means

Ruud and Rheem furnaces share the same controls, and their seven-segment display lists 22 as Main Limit Open. Rheem's (-)801T installation instructions call it Main / Aux Limit Open, and the 801S, 90P two-stage and serial communicating fault code label (92-103343-01) all list 22 as main limit open, next to 23 (heat assist limit open) and 33 (manual reset rollout limit open). The main limit is a factory-set temperature switch that keeps the air leaving the furnace from exceeding its maximum outlet temperature; when it opens, gas heat shuts down. Rheem's manual says the reasons for a limit to open almost always involve low airflow through the furnace, and lists a dirty or restricted air filter, a dirty or restricted cooling coil, an undersized or restricted return or supply duct system, blower problems (wrong speed tap, failing motor bearings, low voltage to the motor, dirty blower wheel, wrong rotation, wheel slipping on the shaft, or a failed motor), overfiring with too much gas pressure, and ventilation problems. If the main limit stays open during a gas heat call for more than 150 seconds, the control decides the blower is not running: the display alternates 61 and 22 until the limit re-closes, then the furnace goes into a one-hour soft lockout showing 61 and 10. After four of those dead-blower lockouts in one heat call it enters a hard lockout. Rheem's troubleshooting chart for the R96V groups 22 with 33 and says to check airflow, limit wiring, rollout switches and overfiring. Ruud tankless and tank water heaters use their own code lists, so this page covers gas furnaces with the two-digit display.

Likely causes

Safe DIY checks

⚠ Before you start

Turn off power at the furnace/HVAC service switch and the breaker before opening panels. Shut the gas valve before any work near the burners, and never disconnect or alter the gas line. If you smell gas, leave the house and call your gas utility.

  1. Write down exactly what the display shows, including whether 22 alternates with 61 or 10.
  2. Turn off power to the furnace before touching the filter. Replace or clean the air filter even if it doesn't look bad, and make sure it is the right size and installed in the right direction.
  3. Open all supply registers and clear anything blocking return grilles, such as furniture, rugs or curtains.
  4. Restore power and set a heat call. Check that air is blowing strongly from the registers once the burners have run for a minute or so.
  5. If the code was 61 and 10 (one-hour lockout), you can wait for it to reset or cycle the heat call; don't keep restarting it repeatedly.
  6. Don't jumper or bypass the limit, and don't reset the manual rollout switches inside the burner compartment yourself. If 22 comes back with a clean filter and open vents, call an HVAC technician.

🛠 When to call a pro

  • 22 keeps returning after a fresh filter and open, unblocked vents.
  • The display alternates 22 and 61, or the blower isn't running or sounds weak; the motor, wheel or wiring needs checking.
  • A temperature rise check is needed: Rheem says to compare supply minus return temperature with the range on the nameplate, and too high a rise means low airflow or high manifold pressure.
  • The cooling coil or blower wheel needs cleaning, or the duct system is undersized or restricted.
  • Gas pressure or input needs to be checked and adjusted for overfiring.
  • You also see 33 (rollout limit open). Rheem's manual says not to jumper or reset the burner-box over-temperature switches yourself and to have a qualified installer or service agency find the cause.

Parts that commonly fix it

Always match the part number to your exact model.

⚙

HVAC air filter

A dirty or restricted filter is the first cause Rheem lists for a limit trip. Match the size on your current filter.

Search eBay →
⚙

Blower motor

Only if a technician confirms the blower has failed; match the furnace model and motor horsepower.

Search eBay →
⚙

Carbon monoxide alarm

Good insurance for any gas furnace, especially one that has been overheating.

Search eBay →

Sources

  1. Rheem (-)801T installation instructions 92-24161-164-01: display code 22 Main / Aux Limit Open; dual fault rule (main limit open over 150 seconds, 61 and 22 alternate until the limit re-closes; dead-blower one-hour lockout 61 and 10, hard lockout after four in one heat call); Limit Control section (reasons a limit opens: filter, cooling coil, return and supply restrictions, blower problems, overfiring, ventilation, failed motor); temperature rise check (distributor-hosted copy)
  2. Rheem serial communicating gas furnace fault code label 92-103343-01: 22 Main Limit Open, 23 Heat Assist Limit Open, 33 Manual Reset Limit Open
  3. Rheem R96V installation instructions 92-24161-124-01, troubleshooting chart: when the display shows 22 or 33, check airflow (filter, blower wheel, dampers, closed registers), limit wiring, rollouts and overfiring (distributor-hosted copy)
  4. Ruud 801S Series installation instructions, Diagnostics and Fault Codes (ManualsLib copy): 22 Main Limit Open and the 61/22 dual-fault display

Last reviewed 2026-10-25. Always confirm against the manual for your exact model number.