My L4006A Honeywell Taught Me A Lesson

That is, always check your safetys!
The Axeman ran away the other morning and went over temp, spewing a lot of vapour and had the girls pretty excited. I shut it down and let her sit for a bit and she kept running every time I restarted it. After a bit she reset and ran normally but I knew there was something not quite Kosher and did not leave her on when I left the house, switched back to oil for safetys sake.. When I had the time, I returned to trouble shoot the problem. My first thought was, when I bought it used I had removed all the controls to avoid any damage during the move. I removed the controls with their wiring back to the junction box and figured I may have made a mistake when rewiring it. Well the wiring appeared to be correct so the next step was to exaine the L4006 itself. I removed the cover to discover that both wires were on the same terminal. Well no wonder it ran away, but why on earth would someone do that? I wired it correctly and switched it on and it wouldn't start, that explains why they did it. A quick meter test showed that the switch was open and no adjustments to the temperature setting wheel changed its open state. Hmm, bad switch? Removed the switch and tested it. In its normal position, it showed open. I found that odd because the control is designed to open when actuated but the switch when actuated closed. So that meant a working switch but appeared to be operating in reverse of what was expected. Perhaps the wrong switch was installed at the factory? Nope, upon examining the mechanisim's operation it appears to be correct. The adjusting wheel pushes the paddle toward the switch on increased temp and the paddle showed contact with the switch button. Well if everything is freed up and working, let's try it. Put it back together and it worked like a charm, something was hanging the paddle up and holding the switch open for the last 34 years. I have added a simple procedure to my routine to test the safety periodically which consists of turning the adjusting wheel down when it is running to see that it shuts down at the temp the boiler is at to insure it is working properly. You should too.

So why did it wait until now to overheat?

The 4006A is supposed to be the high limit during timer cycles right? Make sure your timer hasn't failed as well.

Good catch regardless. Lesson learned to always verify the function of each control.

I guess it took that long for the aquastat to hiccup. The boiler was only run about a month by the original purchaser. He got sick of having no interaction with it, shut it down and went out and bought a woodstove for something to do. It sat for 28 years when I bought it.
The timer gave up years ago. Not much need for it with an Axeman, the beast will go about three days with no power and come back to life in minutes. The over limit control is autonomous of anything else and wired prior to the motor, it should perform under any over temp condition.

Good advise there Coaldsweat, check your safety from time to time to make sure it's safe!

-Don