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Does the hot surface ignitor glow at start up?
What happens after the HSI glows?
It lights up, the burner goes on for a minute then all of the sudden shuts off completely. Then there is a clicking noise from the White-Rogers Intelli-Vent Control and the ignitor comes back on and this process continues a few times before an error code is displayed. Error Code 6.
The only thing left is the flame sensor. Try replacing it and the lead from it. Maybe just cleaning it wasn't enough.
On page 24 of the manual for the intellivent it mentions the following:
Gas supply is off or too low of pressure to operate.• Insure manifold gas pressure is present and within requirement.• Insure the flame sensor is making good contact with the burner flame. See theIgnition and Flame Failure bulletin on page 16 and the burner check on page 18.• Insure the flame sensor is clean - use steel wool to clean sensor.• Insure flue restrictor (on models so equipped - see page 19) and flue baffle areinstalled properly. Flue restrictor must be flush on top of flue pipe. A disloged ormissing flue restrictor/baffle can cause excessive air turbulence in the combustionchamber - sweeping all gas away from ignitor (no ignition) or the flame away fromthe sensor (short cycling burner).• Insure vent termination restrictor (see product notification sheets at end of thispublication) is installed when required.• Insure the ignitor is positioned correctly for consistent ignition.• Low voltage to the water heater. Should be 115 - 125 VAC.
I am not sure how to get to the flue baffle to check it. Or other things they mention....
I don't want to have to pay for hours-and-hours of labor for this. Yikes.
The flue baffle issue should have been raised by AO Smith if it was relevant. You told be you have ignition so the ignition related issues should not apply. Since you have ignition, flame rectification is the next step in the process. That's why I mentioned replacing the flame sensor. This is a fairly new model so I assume it hasn't been installed for too long and is still under warranty. If you want to avoid additional unnecessary expense I'd suggest you get back on the phone with AO Smith and tell them their solution isn't working and you want a warranty tech to come out and fix this or you want a new heater.
AO Smith has specially trained technicians that deal with warranty related problems. They approached me several years ago and I declined (I didn't like their terms). So, unless you live in a very rural area there probably is a local tech that can come check this out for you. Given the difficulties involved with diagnosing this problem I wouldn't recommend you try and fix this yourself.