GE mod JGBP79WEA1WW ser RT228069P oven temp slow to stabilise

[slantsixdan]

Yello, all. Subject gas range on propane seems to be misbehaving: Hit "bake", enter desired temperature, hit "start", but when it beeps to signal the target temp has been reached, the oven is actually 50 to 75 degrees under the target temperature according to a not-ridiculously-cheesy thermometer and very familiar baked recipes not being finished cooking in the expected time. After about 20 to 25 minutes, the oven temp will stabilise near the target temperature. I removed the oven floorplate and observed the burner: the ignitor glows brightly within a guesstimated 25 seconds of hitting "Start", and the burner burns with the flame shown in the photo attached to this post, which looks okeh to me (though I've no experience judging propane burner flame quality). There's no evidence of a marginally off-spec ignitor causing gas valve oscillation. Maybe a dull thermostat…?

[RegUS_PatOff]

any change in location / installation / gas type ? (conversion) ?

[slantsixdan]

No, sorry, should've mentioned absolutely nothing's changed except the behaviour of the oven.

[RegUS_PatOff]

this may help ...

http://www.mediafire.com/file/odvny1nuig4/31-9008 xl44 tru temp.pdf

 

[Pegi]

Well the burner flame looks way to small to me in that photo, should be going up to the edges pf the spreader....would be guessing something has the burner orifice clogged or the propane tank is way too low of propane or the regulator has gone off??...if this has burners on the top do they still burn ok with a good size flame??

[slantsixdan]

I think you are onto something there — I had your same thought that the flame seemed to indicate an acceptable fuel/air ratio, but looks small and feeble. Also seemed strange that the flame is smaller near the ignitor than at the front of the burner tube. The surface burners do give a good large flame (see attached - big front burner on hi setting) and there's been no degradation in the performance of the water heater or furnace also fed from the same propane tank.

The owner (of whom I'm a houseguest) also reports that on random occasion, during baking, when the oven cycles back on to maintain temperature there's a whooshing sound from the burner, three to four times louder than the normal burner flame noise. There is no smell of unburnt gas or any other indication of improper combustion.

Sooo…now what?

[Pegi]

Leave the oven turned off till the owner can get someone out that knows propane systems,  sounds like this oven is very dangerous and I would not use it until it has been repaired by a professional...not worth the chance of getting blown up...

[slantsixdan]

Yipe! I don't disbelieve you and will see to it a service tech is called in straightaway. But I'd like to understand the danger. Can you elaborate, please?

I've attached a photo of the upper burner (on "hi broil"); this flame looks a little small to me, too; what do you think?

Two more pieces of info from the owner:

1. The whooshing sound has not been heard for several months

2. When this range was purchased new, the (reputable family-owned local) store said it was configured for LPG. However, when it was placed into service, the stovetop burners burned with a carburising flame (orange and sooty). The service tech found that in fact natural-gas burner units (with integral orifice, as it seems) were installed. These were swapped and now the stove burners burn clean and blue. However, the owner doesn't recall any change to the oven at that time.

[Pegi]

Broil does not look as wimpy as the bake burner flame.....if the oven had not been converted to LP you would have known it as it would have been like the top burners before conversion, orange and roaring....looks like something may be clogged up but propane is so dangerous that techs cannot even touch a propane appliance without a special butainers license.....you might try turning the gas off and cleaning out the orifices and burners to the bake and broil in the oven, but I would not if I did not know for sure what I was doing...not worth blowing up the kitchen with you in it...

[slantsixdan]

Thanks much — the oven will not be used until it's been thoroly checked and repaired.

[kdog]

My guess is a failing bake burner ignitor

[slantsixdan]

Kdog, how do you reckon it?

[kdog]

When failing, causes lower current in the circuit of the ignitor and bi-metal in gas valve(which are in series) - then the valve does not open fully, since it is slow to react, also causes these "woofs" as the gas ignites.

Slap an amprobe on one of the leads to the ignitor and check against the recommended draw listed on the tech sheet

[slantsixdan]

Thanks — that makes sense. Don't have the tech sheet, tho.

[RegUS_PatOff]

[user=1736]slantsixdan[/user] wrote:

... Don't have the tech sheet, tho.

Did you download the service manual I posted earlier ?

Give the Oven Gas Safety Valve a whack with a screwdriver handle while it's ON..

That may give it enough incentive to open fully.

[slantsixdan]

Oh, whoops, I overlooked that Regus. Thanks.

[kdog]

The puffing and small flame are classic symtoms of a bad ignitor

 

RepairClinic part #1990

[slantsixdan]

So…what's the consensus, then? The oven's unsafe and shouldn't be used, or it just needs a bake burner ignitor? What do we think of the broil burner flame appearance?

[kdog]

Broil looks ok, you could always swap the 2 ignitors as a test, I have done so in the past to get the bake burner working until I can get back with an ignitor

Probably the best "concensous" is to measure the current draw of the valve/ignitor circuit

p.s. - I  used to love the chryco 225 inline 6, used to service them with my daddy, they were an industrial version installed in agricultural swathers, virtually bulletproof!

[slantsixdan]

Yeah, they are...y'ever hear of the die-cast aluminum 225 slant-6? I have one in my '62 Lancer.

[kdog]

Very cool indeed!! I love the vw bug style flowerpot, nice touch!! I've never seen this model before, thanks for sharing that