new water heaters

Nron_13

Hi guys is anone out there useing the new state Power vented water heaters , were haveing some problems with them locking out and are haveing a hard time pinpointing the cause , here is the problem

Gas valve is locked out and won't reset , unit is locked out on flamable vapor A-C on control unit , we have had more than 20 water heaters lock out on the flamable vapor , and the gas valves won't reset ,and had to be replaced , have also noticed on the new water heaters that the burner seems to pulse up and down lifting from the burner , happens more when the tank is cold and will some times lift the flame high enough to shut down the unit and it will have to restart combustion sequence ,

What chemicals is the flame vapor unit sensitive to ?
we have had some units lock out when the floor is painted even though they have used latex paint , will CO2 affect the sensor , what chemicals can affect the sensor?