Peerless TCII08 issue

Bill_69

New boiler with a Powerflame C2-G-20A burner. Since install, we have experienced intermittent flame fail issues. Fault is ALWAYS a "main ignition fault" at 3-4 seconds. Boiler starts on low fire, pilot always good (5 VDC steady). All pressures, settings, combustion, etc. look good. Flue outlet fixed damper at set pressure of .1" WC per book. I can't understand the cause of this fault. (Never witnessed a failure). I'm considering making "slide bar" adjustment to the retention plate in the blast tube. Does this adjustment only affect gas/air pattern at the burner head, or am I missing something else. Need to mention that the flue draft is also high. (Apx. -.10") I know it's too high, but identical older boiler next to this one has same flue draft, and identical flue piping. Older boiler never faults out.

ScottSecor

Main flame failure is rare with your setup. Could gas pressure be an issue, especially when both units are firing? Perhaps one burner is 'starving' for fuel and flame is lifting off the diffuser?

In most cases you can actually hear the flame is unstable when firing. Check the flame signal on pilot, low fire, and high fire. If it's a full mod burner I would also check the flame signal at points between low and high fire. Around here (NJ) we've had the gas company install a paper chart recorder to test for gas pressure. On a few occasions we learned that they undersized the piping, meter or even the regulator. However, I must admit this is rarely the cause.

If your burner has the black knobs with the locknuts underneath and the gas pressure checks out, I would not hesitate to make an adjustment. Watch the flame signal and listen closely as you make small adjustments. This has saved us a few times in the past. Think like the UV sensor, you may able to see the flame from the sight ports with your eye, but if the sensor struggles to see the flame because it's not in 'focus' with the scanner your will get nuisance flame failures.

Bill_69

Thanks for your input. Never thought about the other boiler causing a drop in fuel pressure. I will see when I get back there, and monitor main gas pressure. As far as the adjustment- my burner doesn't have black knobs, but it has a slide bar of some sort that will move the retention plate in or out. Is it the same sort of adjustment?

lchmb

Is this LP or natural gas?

Bill_69

Natural

Steamhead

That slide bar moves the drawer assembly and head back and forth to adjust the shape of the flame. But IIRC the UV scanner is fixed in position on the air tube. What position is the slide bar in now, and does the flame shape match the firebox?

Bill_69

The slide bar only moves the end plate nearest the flame (looks similar to prop fan blades on a rod end) Does not move a tube. The "bar" is locked in apx half way in the adjustment slot. All the IOM says about it is that it is adjusted for "smooth light off". I'm not sure what you mean about flame shape matching the firebox. I only know that the flame signal is very stable (5 vdc) on every cycle I've watched.