Gas oven repair question

Post by **jacob** » Mon Oct 25, 2010 2:12 am

Our gas oven won't switch on anymore.
The pilot light works. When I turn up the heat, the pilot light flame grows in size to reach the burner.
The burner does not ignite. There is no smell of gas.
My guess is that either the valve to the burner is busted or the igniter is busted in the sense that it doesn't tell the valve it's lit. It looks like there's a copper wire going from the igniter to the valve---I suspect this wire heats up thanks to the increased heat from the pilot light when the oven is turned on and then tells the burner valve to open up. Does that make sense?
Any ideas how to check this?

HSpencer · Post by **HSpencer** » Mon Oct 25, 2010 3:52 am

On some RV ovens, the pilot flame heats a thermocouple, which then supplies 750 milivolts to operate the oven valve. It is also a safety that unless the pilot is on, then the thermocouple is heated, keeping the oven valve on. Otherwise, the OV shuts down automatically. Test the wire from the thermocouple for around 750 milivolt output with a volt meter set to milivolts.

The value of the voltage may be less depending on the type of OV.

Gas furnaces operate at 750 mv. A clue would be to see if the oven itself is hard wired. If not it's a bet the valve is mv operated as described. Oven may have power wired if there is an oven light however.

Good luck!!

An RV store should have a new thermocouple. Provide make and model oven.

HSpencer · Post by **HSpencer** » Mon Oct 25, 2010 5:41 pm

http://www.liveworkdream.com/2008/02/20 ... ven-pilot/
This is a Magic Chef Brand, but the principle may be the same.

Post by **jacob** » Mon Oct 25, 2010 9:09 pm

Thanks!! Turns out that "thermocouple" was the keyword in my failing google searches.
http://www.appliance411.com/faq/gas_ran ... tems.shtml
Our setup is exactly like the pilot light ignition system depicted. I suspect it's the pilot and or thermocouple that got covered in dirt/burned off. I'll try to clean it. If nothing else, I can take the entire system off and take it to the RV store. Unfortunately, the sticker with the model number is unreadable.
Through some moderate use of violence I got the broiler plate off yesterday.

HSpencer · Post by **HSpencer** » Tue Oct 26, 2010 12:14 am

Great!! An RV shop could easily test the burner/thermocouple for you with a VOM---(Volt/Ohm/Milliamp meter).

They would heat the thermocouple with a torch to see if it generated the needed micro voltage to operate the valve. And a good cleaning is always in order on such a repair.

Post by **jacob** » Tue Oct 26, 2010 12:26 am

I got the multimeter and a butane lighter with a 1500F flame.
It's not clear to me which two points to test between, since there's only one wire and it disappears into the valve housing.

HSpencer · Post by **HSpencer** » Tue Oct 26, 2010 12:36 am

"If the pilot is extending but the oven gas valve is not opening, that oven safety valve may be defective or its sensor bulb may be out of position on the pilot or just dirty causing it to not sense the proper temperature of the pilot flame. A dirty pilot can also cause a reduced size pilot flame so the oven safety valve can not sense the proper temperature to open."

(above para from your link)
If it is a "sensor" rather than a "pilot generator" it may be a defective sensor to the valve, rather than a voltage operated valve. There are both types. A thermocouple should have a braided wire with two terminals at the valve body. I am now suspecting it is a sensor instead. See if you can remove the sensor from the valve. Should be a small nut on that end where it goes to the valve.