Slant Fin Won't Light All Burners

Steve_R

I just finished my installation of my Slant Fin VHS-120. Did the LP conversion and changed orifices to 60's (I live at 8,000 ft elevation) When I get a call for heat, the blower comes on, pump comes on, pilot lights and proves, and the gas valve comes on. Usually only the burner rails near the pilot will light. Of 8 rails, usually only 4 will light. I seem to have good flame quality but I have to blow into the burn chamber to get the other burners to light. Once lit, they are fine. Other times I will give it a call for heat and all 8 burners light, no problem. I'm struggling with this one, and of course it's on my own house. Any help is appreciated! -Steve

SWEI

Have you checked the gas pressure on both sides of the regulator (both off and when firing)?

unclejohn

Did you change the regulator spring in the valve as well as the orifices.

Steve_R

Unclejohn, I did change out the regulator spring in the LP conversion. SWEI, I haven't checked both sides yet. I find it strange that some times it lights, no problems at all. Other times it will only light 3 or 4 rails.

Steve_R

Alright, I checked LP pressure and incoming was 13 3/4", manifold was only 6 1/4" so I turned it up to 9 1/2" as per the conversion specs. I still had trouble getting all the burners to light even with the increase in manifold pressure, so I started closing the shutters. Now, with the shutters a bit under 1/8" open, it lights all burners and fires fine. The conversion kit for this altitude came with #63 orifices. I also have #60's, so I wonder if I should put in the #60's?

unclejohn

I would get your LP CO. to come out and do a combustion test, It will be way worth the money.