Flame Fail Igntion on Lochinvar

Rizz861

I’m having issues diagnosing this error on a lochinvar unit (WHN155). The unit was just serviced so ignition components are brand new. Igniter cable tested at just shy of 1000ohms. There are no grounding or venting issues. With cable removed from board, unit is making a nice spark. Gas pressure has me wondering. They have been doing a lot of gas work in the streets in this town. And I mean a lot. My inlet pressure is only 6 IWC and I usually see around 9-10 in my area. At 100% the inlet drops to only 5IWC, only 1 IWC above Lochinvars min inlet pressure. During pre purge the gas in outlet goes from I think it was like -5 IWC to -0.25 IWC. I’m still waiting for a call back from Lochinvar, but I thought the outlet PSI was suppose to go to positive pressure after pre purge and gas valve is open. What do you guys think?

Ironman

You have inadequate gas supply.

HomerJSmith

When did this happen? What changed?
Normal Nat gas static pressure is 7" w/c. Minimum gas pressure is 4" w/c and max 14" w/c for Lochinvar.
Static gas pressure is set at the meter's regulator. The delivery operating gas pressure depends upon the gas piping from the meter to the appliance and other appliances that operate simultaneously. The piping should be calculated to provide adequate gas delivery to all appliances when all are operating. There is a minimum acceptable pressure drop when an appliance is operating. Excessive pressure drop of an operating appliance indicates to me that the size of the piping is inadequate.
Corrugated Stainless Steel Tubing connection from the supply piping to the boiler must be sized to the BTU required by the boiler.
The gap on the igniter probe should be about two quarters (coins) wide.
Check the corrective actions for that fault code in your Service Manual.
Have your gas suppler increase the pressure at the gas meter, adjusting the regulator to provide 7" w/c.
Unplug and re-plug all the connectors to the Control Module Board, carefully.
Do a combustion analysis on the boiler with a recently calibrated meter.

Rizz861

@HomerJSmith @Ironman Hey thanks for the input guys. As i suspected this one turned out to be a supply issue and the gas company came out and bumped the pressure up. So far so good. In case everyone wanted to know, according to Lochinvar my gas pressure readings and other readings didn’t warrant this lockout. The only thing they said it could have been was a need for combustion analysis/cleaning, but that was done and the numbers fell with in specs. 

Derheatmeister

Did the Unit "Rumbel" at low fire ?
Sometimes we find that the Ventury is in need of cleaning !
Even a little deposit on the Brass "orifice" will cause serious combustion issues !