Older Rheem shutting down.

Old 10-29-17, 01:43 PM
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Older Rheem shutting down.

I have an older Rheem 80 plus from I think 1987. I tried to fire it up last week for the first time since spring. Put a new filter in and found out once the furnace was going for about 10 seconds the flames went out. The circuit board only has an LED with a max of 3 codes. It was blinking twice which indicated a weak flame signal. I don't have a flame sensor rod but it is an HSI unit. The HSI is about 4 years old. I put an ohm meter on it and got 158 ohms. Since pulling it out, inspecting it and reinstalling it now fires for 4 seconds and flashes 1 flash indicating ignition lockout.. only other thing I have replaced was the circuit board 2 years ago. I read the HSI should be around 40-70 ohms. Thought?
Old 10-29-17, 02:05 PM
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Welcome to the forums.

Your HSI does sound like the resistance is a little high although that usually doesn't affect its flame sensing ability. The HSI does need to be fully engulfed in the flame though.

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