Peerless 211A help

John McArthur_2

I have a 211A with the RM7890 burner control that keeps going into lockout. The boiler is a nat. gas unit and I have checked the high and low pressure safety switches on the gas train. The manifold press. is 3.5" w.c. When I test the dc volts at the flame amplifier, I get ~2-4vdc with the pilot lit. None of the safties trip but it keeps intermittantly going into lockout.

The only odd thing I have noticed is that the power light on the RM7890 blinks on and off at a slow pace. I don't know if this indicats line noise or is normal. I have read through the literature but since I have never witnessed the boiler go into lockout, I don't have any idea what is causing the problem. The problem occurs summer and winter so it is not a temp issue for the control or flame amp. The boiler sits directly in front of a louvered door. I don't think it is a draft blowing the pilot out because I have been in the room for hours with the boiler in operationg w/o issue. The second boiler has ran about 4x as many hours in the past year as the problem one. The second boiler is older and has the 24v control/ignition system.

Any help would be greatly appreciated. Thinking about getting a display module for the burner control to help troubleshoot.