Thermocouple Replacement · Bellevue · Eastside WA
The thermocouple is the single most common cause of pilot light failure. Replacement is a quick repair — usually same-day. We carry common parts on the truck.
Most common repair
These two components do similar jobs but aren't the same. Knowing which one your fireplace uses helps us come prepared with the right part on the first visit.
Thermocouple
Generates a small millivolt signal (around 25-35 mV) that holds the pilot gas valve open. Used in fireplaces where the pilot assembly is completely independent — you light the pilot manually and it holds itself open. Failure: pilot lights but goes out after 30-60 seconds.
Typical output: 25–35 mV. Minimum needed: ~18 mV.
Thermopile
Generates a larger voltage (around 300-750 mV) that powers the gas valve and sometimes a wall switch or thermostat. Used in fireplaces where you control the flame height from a switch or remote. Failure: fireplace won't respond to the switch or shuts off randomly.
Typical output: 300–750 mV. Minimum needed: ~150 mV.
The Symptom Pattern
The classic thermocouple failure symptom: you hold the pilot button, light the pilot, count to 30... and the moment you release the button, the pilot goes out. That happens because the thermocouple needs to heat up enough to generate the signal that holds the gas valve open. If output is too low, the valve doesn't stay open.
Sometimes it's gradual — the pilot used to hold fine but now it goes out faster and faster. That's the thermocouple weakening over time. When output drops below the valve's threshold, it stops holding.
Google reviews
“The technician found a minor problem that I would have overlooked during a chimney inspection. He gave me straightforward repair options and a clear explanation without putting any pressure on me.”
Kathleen Kimura
Verified Google review
“We noticed some cracks in the chimney and weren't sure how serious they were, but they carefully inspected everything and only recommended the repairs that were actually needed. The whole process was smooth and well-organized, and the chimney now looks solid and secure again.”
Emanuel Leavitt
Verified Google review
“I'm really impressed with the service we received for our new pellet stove installation. Everything was done carefully to spec, and they took the time to clearly explain the safety steps, which made us feel confident using it.”
Bruce Cropper
Verified Google review
“The technician spotted minor damage to my chimney crown that I hadn't noticed and quickly took care of it. He explained the repair options clearly and made sure everything was solid, which I really appreciated for his honesty and skill.”
Jean Hill
Verified Google review
“Prime Chimney was suggested by a neighbor, and I now see why. They were easy to book, arrived on time, and completed a thorough job. The technician was courteous and left no mess. Our chimney is clean, safe, and ready for the colder months. Wonderful local enterprise!”
Manuel Laporte
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Got Questions?
Describe your symptoms — pilot behavior tells us a lot before we even arrive.
Fix It Today
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