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CRITICAL URGENCY

Rheem Code 33 - Rollout Switch Open (SAFETY)

Code 33

Rollout switch tripped - possible cracked heat exchanger and CO risk.

Brand: Rheem (Also covers Ruud)  |  Equipment: Gas Furnace

SAFETY: Cracked heat exchanger releases carbon monoxide. CO is odorless and colorless. Evacuate and call 911 if anyone has headache, dizziness, or nausea.

What This Code Means

Code 33 on Rheem (Ruud) means the flame rollout switch has opened. Flames are escaping the burner enclosure - serious combustion problem.

Likely Causes (Ranked)

Common and serious

Cracked heat exchanger

What: Crack lets flames escape.

How to check: Licensed tech inspection only.

Fix: Heat exchanger or furnace replacement.

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Common on 90%+ AFUE

Plugged secondary heat exchanger

What: Condensate buildup blocks passages.

How to check: Tech inspection.

Fix: Clean or replace.

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Common

Blocked exhaust vent

What: Birds, ice, dropped pipe.

How to check: Inspect outdoor exhaust outlet.

Fix: Clear blockage.

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Diagnostic Steps

  1. STOP - do not keep resetting
  2. Shut off gas at furnace
  3. Verify CO detector working
  4. Call licensed HVAC tech

Frequently Asked Questions

Can I reset the rollout switch and keep running my Rheem?
No - CO risk with cracked heat exchanger. Get an inspection first.
Cost to repair?
Heat exchanger \$500-1200 labor (part often warrantied). Often cheaper to replace furnace.
Same on Ruud?
Yes - identical control system.

Related Rheem Codes

Rheem Error Code 22

Related Symptoms

Furnace Smells GasFurnace Pilot Yellow Flame

Need More Help?

Try our interactive symptom diagnostic tool or browse Rheem parts.

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