Baso Bother, Valve Vexation

ETA: We're back in business! Against all odds I got my burner fixed (after I ordered another one, of course) I'm firing right now, even though I will likely have to be up all night with it. See you Saturday for the unloading!! Or pop by any time during the tour, it's gonna be fun! 

I guess it's time for me to learn something new! I love learning new things...in theory. I love it le
ss in those urgent, figure-it-out-or-fail situations that I seem to find myself in all too often. On the other hand, things turn out ok a ridiculous amount of the time, as well, and not always or even usually because I figure things out. 

Let's hope I do this time.

Last night I turned the pilot lights on, to candle my firing overnight. This is the firing that will be unloaded during the Maine Pottery Tour, so I kind of need it to happen on time. The pilots lit, no problem, although the gas pressure on one - the one which later had a problem - did seem low; they were still burning in the morning, no problem; then I opened the flow regulator to turn on the burner proper. 
What should have happened: gas should have flowed out of the burner & immediately ignited when it encountered the flame of the pilot. Exactly like a gas burner on a stove, except larger. What did happen: nothing. 

There are only a few things that could have gone wrong here. Gas is getting to the pilot, so we can eliminate the valves upstream of where the line to the pilot diverges from the line to the burner. There are three valves involved beyond (or at) the point of separation: the baso, a safety valve that shuts off the gas if the pilot goes out; the solenoid, which senses whether there is power to the blowers; and the flow regulator valve, a very simple device that controls how much gas is passing through the line. 

The Baso Safety Shutoff Valve

The Solenoid

The Flow Regulator Valve

We can...I think...eliminate the solenoid as the problem. I can hear it click open when I plug in the blower.

We can probably eliminate the flow regulator, as it is such a simple device that there's not really anything that can got wrong with it - at least nothing that could have occurred in the two weeks since I last fired. (This short interval, along with the season here in Maine, rule out things like insect activity.) 

That leaves the baso valve. The function of the baso is to shut off the flow of gas to both burner and pilot if the flame of the pilot goes out for any reason. It's attached to a thermocouple, a sensor which contains two pieces of metal that expand when hot, closing an electrical circuit which then opens the valve. Conversely, when the metal cools, the pieces shrink and are no longer in contact, so the circuit is broken and the valve it shut. The default position of the baso is in the closed position. There's a button to temporarily open the baso valve, which allows us to light the pilot only. My theory is that my baso is stuck in this intermediate position. 

The baso is an expensive part and sort of messy to replace - I have to disconnect a bunch of other stuff to do so - so I'd rather not replace it if I don't have to. With that in mind, I started googling, and found this article from 2003 by Marc Ward, with some wisdom about first steps before you go disassembling your burner to replace a baso valve. In short:

• Make sure your pilot is a continuous blue flame. Mine was not! I scrubbed the ports of the pilot & cleared them with a needle tool. Now the flame, while still low, is steady blue. This did not solve the problem.
• Ward suggests hitting the sensor end of the thermocouple with a handheld propane torch, until it glow orange. I did this. This did not solve the problem, but it did change the problem: whereas before, when I went opened the flow regulator, nothing happened, now when I open the flow regulator the gas shuts off to the pilot as well. Open flow regulator, pilot turns off; close flow regular, pilot relights. I'm gonna count this as progress. 
• He also suggests cleaning the contact between the thermocouple and the baso. That's next on my list.
  
• Lastly, if cleaning the contact fails, I will replace the thermocouple. That's a relatively cheap fix - might cost me $15 - and even if it's not the problem, it's good to have a spare thermocouple around. 
  
  

Not that it's worth mentioning but all this is happening in the icy, pelting rain. Rain doesn't much affect the firing but the potter? That's another story. 
Anyway, I've finished my coffee & it's time to venture back out into the cold wet. I'll let you know how I fared.