Hello, Error code 11 on this unit is failure to detect ignition.
How long has this unit been installed? What is the fuel type?
Do you know if this unit has it's own regulator feeding it?
installed about 2 years. if it would be located outside of unit then no
it has been working fine up until recent?
no 4 weeks ago error code 12 was coming up. called installer. after aweek he replaced and or cleaned burner plate. found bits of leaves inside
So the installer cleaned the burner, and now your getting this code 11 in the last few days?
this morning no hot water
ok, lets try to reset it, and see if it will run. Turn off the power on the display, then unplug the power from the unit. Wait about 30 seconds, then plug it back in. Give it a few seconds to boot up, and turn the power on and see if it tries to light.
I will be waiting while you do this, I would just turn on a couple of lavs or a laundry sink for the hot water draw test.
OK, did you get an error code 11? or do nothing at all?
ok... then the next steps are a bit technically involved.
The next step would be to check the gas pressure going to the unit, verifying the ignitors are clean and properly aligned.
I would recommend that you contact the installer or Rinnai directly to have a certified service agent check your unit out.
There is not too much else I can do without standing in front of the heater at this point.