NTI ignition issue.

[scarey8]

NTI Model Tx151C
Serial 123354

I started looking after a customer with above appliance in late Oct 2023.  Initially called to site for ignition issues, boiler required service and cleaning.  Ignition components cleaned, combustion chamber cleaned with water with 90 degree nozzle to spray between flue passages of water tubes.  Drain line cleaned and double trap on drain line corrected.  LPG 13" static, high fire 11.96" maintained at boiler inlet pressure tapping. Eventually found intermittent connection issue to gas valve at harness, corrected connection and the boiler has worked for 3 months without issue.

Last Friday rolls around, boiler off on ignition issue again.  Boiler would light, but would not create stable flame sense to release to modulation.  Adjusted combustion readings and eventually flame was stable, combustion numbers set to manufacturer rating. 

Boiler ran fine over the weekend, flame failure today, on arrival boiler would ignite, but not enough flame current.  Removed burner from unit, in handling the motor and gas valve assembly I could hear fluid sloshing, found about a TBSP of water that would have either been in area of the vent motor discharge or in the premix tube that leads to the burner.  Drained water from this and boiler lit off without without issue.  This boiler takes combustion area from the room, zero moisture in drip leg, drain line clear.  Heated boiler to 180F, quickly removed burner to see if heat exchanger was leaking at design temp, no leakage found. 

TBSP of water that was found in the vent motor was dirty black in color, drained the boiler water as a sample and the boiler water is clear.  Tech support has no idea as to where the source of water would be.  No condensate leaks or water leaks at the boiler or in the area of the boiler.   

anyone see this phenomenon before???

[Porcupinepuffer]

Nope. Was there any signs of poor condensate drainage inside the chamber? When I'm almost done cleaning, I also go between all the tubes with a credit card. Depending on the situation, there could be some good crud buildup that the spraying and brushing isn't getting. I then dump a good amount of water right into it to flush anything else right down the drain.

[scarey8]

The combustion chamber was thoroughly wasted, cleaned hot water as well as a Nylon brush cleaning tool that is used on most of these cylindrical burner setups.  The area where this water got into would mean, that over half of the inside of the combustion chamber would have had to flood.  The burner would have falsed long before that point.  There is just no explanation as to how this water got into the premix tubing or in the combustion motor.