Not just another "Gas oven & broiler won't light" thread.

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Old 02-26-13, 12:28 PM
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Exclamation Not just another "Gas oven & broiler won't light" thread.

I needed a new oven.
My friend who works in remodeling, brought me a gas range, salvaged from a slightly flooded house (In Atlantic City - flooded by Hurricane Sandy).

Among other things, the flooring was to be replaced in that kitchen, so although it is possible the oven was in about 8-10 inches of water for a small period of time, the range looked like new inside and outside.

It is a convection/gas range oven
Model: Kenmore 79072904012

The problem:

My friend swears that while he was working in that house he used the oven part of the range numerous times and it was working great.
We installed it in my place. The top burners (spark ignition) work fine.
But somehow, after we installed it in my place, the oven and the the broiler are not firing.
We could see the bake and broil ignitors glowing, but no firing, and no gas smell.



Troubleshooting:

Initially, like any diy-er who's never dealt with gas ranges before, i figured that a valve must exist that's electronically controlled that would have to be malfunctioning (what else could it be).
Proceeded to remove the valve with the thought of replacing it. But before i ordered the new part (it's a dual safety valve costing ~$140) i did more research.

I learned that the safety valve is connected in series with the glow ignitor, and that the glow ignitor MUST draw more than 3 AMPS of current in order for the valve to open and stay opened. Usually 3.6 Amps.

First i don't quite understand why in today's world, we need to consume 3.6 x 110V = 400W of electrical power just to keep the gas oven on. It just seems SO wasteful.



Ignitors:

I removed the glow ignitor, hooked it up through an amp meter, directly to 110V AC outlet. It started glowing, and within about 15-20 sec, it was drawing 3.6 Amps (glowing a bright yellow-orange).

So many tests on the internet tell you to check for continuity. Well on my digital multimeter, the continuity "beep" never happens because the resistance of the cold ignitor is something like 382 Ohms. As the ignitor heats up, it's resistance would decrease.
But the amp meter test showed it's working exactly like it should... so ignitors are good.

Next, the gas safety valves.

This is a dual valve (PART NUMBER: 316404901)

I couldn't find any information regarding specific testing of this part.
Not sure how i could bench test this part. (Maybe applying a 3.3V DC to it, and blow through it to see if it opens?)
Resistance is about 1.5 Ohms (which my digital multimeter also considers "continuity"), and both these facts seem to be inline with what i've found on the net so far.



And now the best for last.

After spending maybe 20 hours on research, and reading all those troubleshooting posts and seeing all those videos, i found ...it could be something else..

The regulator (link)

Here's a better view.
See the little silver looking piece on the regulator in the pictures at the links above?

That little thing i believe is a valve flipper that opens and closes gas flow at the regulator...
What exactly it opens and closes, i'm not too sure, because you see, on mine, that little silver piece is MISSING.

What is still there, is the tiny brass rod that the silver piece is supposed to pull outward when it is flipped. There is a pin at the end of the tiny brass rod, that probably used to hold the silver "flipper" attached to the pin.

Could that be the cause of my problems?
That my friend while moving it accidentally broke off that flipper, and never noticed ??
NO GAS because the flipper is missing and so the pin is pulled in (is there an internal spring) ??

But again, the top burners are working. And all gas goes through same regulator.
Well... Upon further examination, the regulator has 1 input (main input from flex hose) and 2 outputs.
One output goes to top burners.
The other output goes to the bake/broil safety valve.

So it looks like, after spending all this time looking at other things, it could just be that my problem is .... a broken flipper....
And no troubleshooting guide i've read or seen mentions anything like this...

Now i could buy a new regulator, but i mean all it needs is something to hold that pin pulled out...i suppose.
I don't know if i can just buy that silvery flipper tab.

I tried (not very hard) to pull it outwards with a needle nose pliers with the idea of jamming it in the open position, so that at least temporarilly i can test the oven... but it didn't come out. Is that spring so hard?

 

Last edited by tintino; 02-26-13 at 03:11 PM.
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Old 02-26-13, 06:37 PM
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Another pic showing the lever (that broke off mine and got lost)
[ATTACH=CONFIG]9660[/ATTACH]

Also an update...

I pulled the bent pin out of the rod, and threaded a long wire through the hole where the pin was, on the rod.
Then I was able to pull the brass rod outward with my fingers and confirmed that only THEN, gas was flowing to the oven/broiler dual safety valve.

Unfortunately that brass rod doesn't stay extended by itself...because of missing lever... so have to fix that.


-Bad news: Cannot buy JUST that little lever.
Either i have to buy new regulator, or hack something up.

I'll hack something up just to hold the brass rod extended outward (piece of pen plastic tube with hole in it to thread a thin steel wire through it... is first thing that comes to mind at the moment)
 
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Old 02-26-13, 07:29 PM
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I don't believe the gas valve is in series with the ignitor. The circuit board monitors the current drawn thru the ignitor and when it reaches a certain current the board tells the gas valve to open.

If you just have a regulator problem ....... when you turn on the oven.....the ignitor should glow and reach proper temp and then you should hear gas valve click. If that happens you just have a regulator issue. If you hear the gas valve opening (a click) then you may have a control board issue.

It looks like that regulator is setup for easy conversion from natural gas to propane. That is probably the part that is damaged. I'm not sure I would attempt a modification to that regulator. The regulator is fairly inexpensive for that unit.

Does the convection part (electric element) operate ?
 
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Old 02-26-13, 08:28 PM
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Thanks for reply.

Well... As i pointed out, i already tested...

My problem was ....the lever of the shut-off valve (part of the regulator) was missing (probably broken off during the move..since it's exposed on the low left in the back of the oven)

Without that piece, the tiny brass rod, is pulled into the regulator by it's internal spring, and gas was cut-off to the line that goes to the dual safety valve (bake/broil)... so everything i tested was waste of time.

To test, i just pulled the tiny rod outwards, with my finger, after i threaded a longer wire through
it...to make it easier to pull. Once i did that, gas came out on the line... i had that line disconnected since i had taken off the safety valve (was almost about to spend $140 to replace it..but thanks god i started doing research on how this stuff works..hehe)



Now...about the glow bar and safety valve... being in series...

-Mine is in series.
-Circuit on printed paper that was attached to the oven, shows it is in series.
-All i've read on internet... is that they are ALLWAYS in series .. glow bar + safety valve.


From a safety point of view, it makes sense to have in series.

Initially the glow bar (being cold) has a high resistance and not allowing enough current to pass through it. As it warms up, its resistance decreases.
At one point the safety valve gets enough current to open the gas flow.

Should something happen to the glow bar ...ie: break or not being hot enough.. the current is cut-off or reduced simply by the varying resistance of the glow bar....without having to rely on a 3rd party (like a control board).

Not sure you caught onto my rambling of ...how in "today's world".. we need to have our GAS ovens use at least 400W of electricity when the oven is on. It makes no sense, EXCEPT from a safety point of view.

But that's what happens...
When the control board says "fire", that glowbar + safety valve series circuit is provided the juice, and as long as gas is flowing it will spent 400W of power on the glowing of the bar.... of course wasting it as heat.

Not only it's a huge waste of electricity, but these glow bars only last few years and need to be replaced. Talk about a conspiracy

The spark ignition (for oven+broil) technology is not so wasteful as the glow bar technology...
 
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Old 03-01-13, 07:22 PM
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Yes, the regulator/isolation valve must be in the "open" position for the oven/broiler to receive gas.

.
 
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