Had this guy (high efficiency heat/hot water) installed in Jan of this year. Has been great up until about a month or so ago. No heat requirements any more, now just hot water. The sucker intermittently does not fire and posts an E02 error code on the display. E02 = tried to fire 5x and could not. The manual says to check the incoming pressure (this is natural gas), and clean anything related to creating the spark to fire. FWIW, there are no other 'loads' on the natural gas when the failure happens.
Pressing the reset button brings it back to life every time.
Had the installing company come out to look at it, the guy basically scratched his and told me how hard it was to track down an intermittent (no crap Sherlock, that's why I called YOU).
It's still going on, usually every other day. I just noticed that when I press the reset button, code U135 is posted. I can't find what U135 means, either in the manual or using 'the google'.
Anyone have any ideas I can forward to the 'factory trained technician' for his next visit ?
The combustion air intake has no pipe connected to it, as the installers decided that pulling the air from the utility room would be fine (previous boiler and water heater did the same).
I have a louvered door on that room. I now am keeping the door open to make it easier to see the display panel on the boiler and the problem has not gotten any better.