DUCR water heater tune-up. Stuff about Gas burners.

Every spring I have issues getting the first start of a 199,900 kBtuh water heater.

It's well designed in that there's one union nut on the gas line, and three flag terminals to the gas valve+ an ignition lead which also serves as flame monitor- then pull whole assembly out and into daylight. It would be so nice to have a plug&play spare but that seems not cost effective.

I "should" have a spare pilot flame assy, and maybe even a complete brain board just in case. A spare gas valve is on my shopping list too. Having NIB spares is never a bad idea in commercial operations. If they're thought of as "how much will the downtime cost" compared to a spare+ price increases on parts or prices falling as parts become more common? That's a case by case situation indeed. In this case- losing that water heater on a holiday weekend could cost us a LOT.

So- I may update this with p/n's for the heater and pics etc. It may save me or someone else a lot of grief in the future.

The average skilled tech type "Knows" about using two wrenches on a union fitting for example. And that ideally NOTHING mechanical other than perhaps a factory spec cleaning wire should go thru burner orifices when cleaning them. Shop air is even risky as it can break loose, then embed grit/crud from the gas line into that pinhole- so hard that it wrecks a hard to find orifice.

Same not at first obvious applies to manually turning gas valve knobs. some gas valves are *NOT* safe to hand operate!! In fact- the Honeywell style rotary valves CAN be destroyed by a careless hand forcing the fragile mech. Several others just may give you flash burns or similar Very Bad Situations..

Propane's heavier than air. I'm lying on the floor yesterday, lighting the other water heater here when that fact became an interesting near miss. I'd had to pull a Thermocouple and redo it's "spring clip" mounting so it would have adequate cold end contact. Yes- that's important.

I had loosened the flexy to the pilot burner and carefully checked the flare nut for tightness/flame tested for a leak when I put things back together.. no leak at that end..but- I was smelling propane a LOT stronger than was "safe" so I began seeking a leak. Found it in seconds..the nut @ the main control assy had worked loose. Yes- perhaps some of us might have checked BOTH ends of the pilot line. Though, I suspect that many folks might skip that absent perhaps reading this or having had similar experiences/training.

Don't become "Darwinbait" by rushing might be a good mindset?

I wrenched it tight- flame/bubble tested and all was safe again- heater lit.. Life is good again.

I will be trying the big heater in about an hour or so. . Details to follow with pics and parts info/additional notes. Learn from my near misses etc as I've survived them:}