Neutral Axis

AO Smith Vertex Water Heater Problem

by on Feb.09, 2012, under Uncategorized

[Updated below]
A few weeks ago I noticed that my AO Smith water heater was flashing a fault message on it’s screen. “Flame Detect Error, A9”. The description says this is typically either from a gas valve that isn’t closing or a bad CCB. I don’t know what a CCB is unless is the “control circuit board”. There were 255 of these errors that had been logged. In an 8bit world, 255 is kind of a special number, so I figure that’s all the errors that it can keep track of.

The installer has been out twice, once finding a loose connection on the gas valve, and once pulling the burner, found a partially melted zip-tie inside. Neither fixed the problem. But at least the problem happened AFTER a heating cycle, so I always had hot water. This morning things changed and I had no hot water and a new error message. “Blocked Air Intake, A7”. I took a look at the combustion air intake outside and it looks fine. So I have to take off yet another afternoon to meet the installer. 3 of those messages in the last 3 hours. It’s been 3 days since the last A9 fault.

I thought I might go straight to AO Smith via Twitter, so after the first incidents went unfixed, I posted this:

@AOSmithhotwater Vertex htr is giving error messages. Plumber stumped. 255 flame detect errors (A9)
The same day they got back to me with:
We can help with that! Please contact us directly at
I did. They didn’t.
Today I replied: @AOSmithHotWater 6 days and no response from anyone at that location. New error message A7 preventing firing now.
They got back with: We’re sorry to hear that you are still having trouble. Please contact us at
I think I’m tweeting with a robot.

[Update: Twitter delivered results. A very knowledgable AO Smith tech called me back and worked with the local installer to find that water was being drawn in thru the combustion air intake and had caused a fracture in the burner. Thus, the flame problem. They replaced the burner and rebuilt the vent system to drain properly. So far, so good.]

[Update 2: Nevermind.  We’re back to the Flame Detect Error again.]

[Update 3: After a total of 6 unsuccessful service calls, I was able to use some of my connections within the industry to get the last part of the water heater replaced, despite their objection to replacing it.  The computer control board.  So with that change, the only part of the original water heater remaining was the tank.  Upon removing the cover from the original one, we found that the plastic around a transformer had at some time become hot enough that there were impressions from the control wiring melted into it.  With the control board replaced, I’m so far at 7 days without an error.]

[Update 4: 12/19/12:  Well it’s been 9 months or so since the computer control board was replaced and no new errors.  If you have one of these, don’t let them just go willy nilly replacing random parts.  If you’re seeing multiple errors all happening at the same time, look to the control board first.]

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