Older Osburn shutting off intermittently

[Tomas]

Greetings,

I have a ~1998 Bay Vista that I purchased used and installed recently. Pilot lighting and startup is working fine, but often after 20-30 minutes it just shuts off, both burner and pilot. I then turn the control valve to off and allow it to cool down, at which point it restarts OK. The question is, would that point to a thermopile fault or are there other things I should be looking at?

 

[DAKSY]

Have you taken a mV reading on the t-pile? What mV did you get?
What do the flames look like just before they're extinguished?
Do they "ghost" or appear to lift off the burner?
You may have a venting issue.

 

[Tomas]

Well, my cheapo meter doesn't do mV, I'll borrow one today. No ghosting that I've seen, but I haven't caught it in the act of turning off yet. The vents are a brand new DV kit that I just dropped down the chimney. I DID have to reduce 4" to 3" on the exhaust, maybe that could overheat it? Thanks for the input!

 

[DAKSY]

New vent kit! Dollars to donuts, you have the intake & exhaust vents reversed. If the intake is ABOVE the exhaust (on the cap)
The HOT exhaust will rise & get sucked back into the intake. There isn't enough oxygen in the incoming air to support combustion.

 

[Tomas]

I wish! No, I marked and rechecked 10x while installing. It actually hasn't done it again in the last two days, maybe it had some scuzz buildup that was tripping it? Sure smelled like it the first couple of hours! I'm gonna just keep lighting it and see if it happens again.