Sorry for the long post, but I want to provide as much information as possible. I have 10 year old LP fired GB 142/30. It is giving me intermittent 6A (sub code 227) some soft, some lockout. By intermittent I mean (recently) about every other call for heat or DHW. Luckily it is summer and I have the time to deal with it.
The heat exchanger was replaced under warranty 18 months ago for a leaking issue.
In the past, when it has started doing this, it was (at first) very infrequent (once every 1-2 months) and a simple reset would take care of it. As time went on it would get progressively more frequent (2-3 times per week) until I took action. My action consisted of removing the ionization rod, cleaning it with a scotch-brite pad (there wasn't much of anything on it and it wasn't deformed or looked like it was overfired), and reinstalling it. The boiler was then good for 6-7 months. It did this periodically for 3-4 years up to now. June 2017.
So I am at the point I in my first paragraph. Intermittent 6A. What I observe. On a call for burner (either heat or DHW) It goes though its boot up sequence, 1. Purge chamber, 2. OC Energize HSI (glows brightly), 3. OL Gas solenoid/valve opens, 4. stays like this for a few seconds, then a very gentle puff of blue flame in the inspection glass for much less than a second, the green flame-on LED on the BC10 flickers once VERY quickly, then HSI de-energizes and a soft 6A appears. It tries this 4 times, then lockout code (flashing) 6A. After 1-2 times of this 4x sequence it will usually start. Green flame LED will be on solid and display shows =H (DHW call). After it starts once, it will stay running until the call is satisfied. Then I can test it using flue gas test mode and It will usually start the first time until it cools completely to basement temperature (several hours). Then it will most likely be a hard start again.
I did notice that this time was the first time that the HSI has been hard to pull out. I have to twist and pull to get it out. Significant friction in between the heat exchanger casting and the shield (I presume), of the HSI. In the past seven years I've never had this issue. It has always slid right out with no resistance at all. I suspect this is due to the deformity of the HSI.
What have I done? Per the manual, both devices (electrode and HSI) check out for resistance and current/voltage specs respectively. When cleaning the ionization rod I also examine the HSI and shield. Up to this point all has been well. Over the past few weeks I have replaced individually: 1. Ionization rod. No difference. 2. HSI and shield. No difference. I had a spare UBA3 so I tried that. No difference. The new devices (electrode and HSI) still check out for resistance and current/voltage specs. This morning I checked gas inlet pressure. 10.10 in h20. (well within spec for LP fired). and gas/air ratio 0.00 in h20. This gas/air ratio is at the very positive limit of spec -.04 to 0.00. I would like to get it to -.02 if possible. The one thing that has me puzzled and may be related to my issue is that I can not seem to adjust the gas air ratio. With the manometer properly connected and zeroed out and then starting the unit in L30 service mode (30% load) I get 0.00 in h20. Turning the adjustment 4 mm allen under the protective screw cap, makes no difference. I did not turn it more than 1/2 turn in either direction as the manual cautions about large adjustments. I returned it to its original setting and put the protective cap back on.
I have also checked the condensate trap and stuck my finger in the condensate outlet at the bottom to be sure it was clear. it does not appear to be a blocked air intake as it doesn't matter if the case is on or off. I can't inpect the entire exhaust, but it is very short and can flash a bright light in from the outside, and see it reflect on the PVC exhaust outlet at the top of the boiler.
This is where I am. Intermittent 6A (227).
I need some further guidance. Any thoughts of what I might be missing? The fact that it is intermittent makes it really hard to diagnose. But fortunately, I can reproduce it pretty easily. Thanks in advance.
Thanks in advance. P...