Triangle Tube Prestige 175 is back firing

richinmd

Thank you in advance to all who respond. My Prestige 175 which is a 2009 model, has never done this and all the sudden it is back firing. Literally shooting fire out the air intake tube that feeds the power blower. I service this unit myself, and have done so for years, and have never had this happen. I have read some threads of people who say this happens occasionally, but my unit never has until now. I'll done a lot of cleaning and checking, the last thing left for me to do is either replace the blower, or wait for my combustion analyzer to arrive on Tuesday and check the air/fuel mixture. But the unit will fire up no problem (I leave the cover off) and it begins to heat the water which is warming an indirect tank. I can see fire in the heat exchanger, and runs for 2 minutes, then a loud pop and blue flame comes out the air intake tube (turn down snorkel), and the flame in the combustion chamber is still on, but it keeps on back firing until I hit the off switch. So it seems to build up fuel in the blower and then starts to combust. Thank you in advance to anyone that has seen this before and can provide some insight.

Big Ed_4

Bad igniter , blocked air intake , low gas pressure or out of adjustment ….

psb75

Shut it down. Call a gas pro.