Oven Burner Problem


  #1  
Old 10-25-02, 04:12 PM
J
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New oven thermostat, oven still not working

I have a O'keefe & Merrit double oven(glass windows in doors) stove from the early 1960's, the model with the fold down glass shelf above the top burners. I just installed a rebuilt oven thermostat(valve), the one without a pilot connection(left side as you face the stove). The main burner will come on but just barely and doesn't get any stronger. In the top part of the stove, on each side, there is some kind of device that the gas pipe goes to from the thermostat...and after this device the gas pipe goes on to the over burner. Each of these devices has a red button that can be pushed in and when I hold it in, on the side with the replacement thermostat, the flames at the burner increase in size and look more normal. When I release the red button the flames go back to just barely visible.

I don't know what these red button devices are for(one for each oven) but I'm guessing the problem is connected to the one on the side I'm trying to use. Can someone help me with this, tell me what these devices are for, if they can be repaired(disassembled, etc...), if what I'm describing sounds like a specific problem, etc...? This stove hasn't been used for about 3-4 years and that may have a connection to this problem. The previous owner told me it worked fine before, but I've found most of the burner and both oven valves to be faulty or leaking so I'm replacing them as I can afford it.

One other question, the oven thermostat valve on the right side is the one with an electric switch built on to it(turns on a red light indicating that the oven is on). The rebuilders sell this one for 250% the price of the one on the right($90 vs $250.00) and I'd like to find an alternative replacement. I don't need the electric switch but the rebuilders want the core turned in. Is there a cheaper way to replace this one?

John
 
  #2  
Old 10-27-02, 06:40 PM
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Hello John. Welcome to my Gas Appliances topic.

The RED reset buttons are on the ASO gas safety valves. ASO means Automatic Shut Off. This is the part your referring to. They have those RED reset buttons on them. They are non repairable.

If the pilot flame is hot and all blue, properly in contact with the safety element, which is mounted in the pilot assembly, one of the causes could be this safety element is weak.

The element is similar to a thermocouple except it has added lenght to reach from the oven pilot assemblt to the ASO. If it's weak or not heated correctly, etc. it will not keep the gas safety valve opened. Replacement of this element is required.

Another possibility could be the ASO valve itself. However, most likely the it's the thermocouple safety element. There is also a magneto head inside the safety valve. This part could be seperately replaceable on some safety's.

Any of the above possibilities could be causing the problem your describing regarding the burner flames. Just be very careful working with the two red button safety valves. They are safety devices to keep the burner from getting gas if the pilot flame is not on or goes out during useage.

As far as that thermostat with the electric switch, you can install the non electric switch type.

If you need further assistance, use the REPLY button to add any additional information or questions. Using this method also moves the topic back up to the top of the list automatically.

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TCB4U2B2B Company Enterprises. Energy Conservation Consultants & Gas Appliance Diagnostics Technicians.
 
  #3  
Old 11-10-02, 01:04 AM
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I have just checked on the price of a thermocouple safety element
(you mentioned it as the most probably part to be replaced) and it is $110.00, an outrageous price for an item that if used in a water heater would cost around $15.00. Before I go any further and search for a better price I'd like to test it. I have a good volt meter that measures millivolts and it's easy to put the element in a flame...but I'm not sure where to make the connections. The positive lead would go on the part that screws into the ASO safety gas valve but where to put the negative lead, and what reading to look for. What would be a weak reading, a strong reading? Can you help me with this?

John
 
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Old 11-10-02, 07:14 PM
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Hello: John

Voltage wise, about 1/4 volt. The center is the positive and the outter casing is the negetive. There will e a white isulator between the two at the end of the thermocouples lead.

Price wise, sounds expensive granted but considering the time the part lasts, not a expensive as it first seems. Checking around for a better price may prove worth while.

If the safety element resolves the problem, the cost of the replacement element will sound cheap when campared to the cost of the safety valve if it is defective.

Good Luck. TCB4U2B2B Company Enterprises.
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  #5  
Old 11-10-02, 11:23 PM
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Thanks for the information Tom.

I'll measure and see if the thermocouple device is bad. But economic reality being what it is I won't be paying $100 for such a device, nor will I be paying hundreds more for the safety device. So that leads to the next question: is it possible to convert the oven to a more reasonable (and more available/generic) way of getting it lit and warmed up enough to bake bread! It seems that the only sticky point would be the size of the threads in the oven valve supply pipe. Since this is an older stove(1960's Okeefe & Merrit) do you know if they used a standard thread size(where the thermostat valve/or adaptor threads into the main gas supply pipe) or is there a different size for every model/brand name. If you know the size can you pass that information on...although I'm sure I can get out my tap and die kit and measure the threads also.

If it comes down to it I'm sure I could just replace the entire gas pipe(in the stove) and drill new holes and make new threads and it wouldn't cost most than $10-20 to do that(plus my time which is abundant at the moment).

Unfortunately I did just buy a rebuilt thermostat for one of the ovens and it would be nice to find a solution that would incorporate that part.

To sum this up, is there any reason I can't find a generic safety valve system that uses less expensive parts. And if that's not possible, how about my converting to different type oven thermostats that are set up with a different(and cheaper) safety system...preferably with electric ignitors since I don't like pilot lights anyways.

ps...I'm a mechanic so none of this looks that hard to do if the parts are available.

John
 
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Old 11-11-02, 05:38 PM
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Hello: John

Yes. It is possible to convert from the type of safety devices currently installed to later model types. A fluid safety with a matching gas valve would work.

The valve would have to be postioned so the burner tube fits over the gas valves orifice. Some pilot assemblies, for other types of burner gas valves, require pilot gas to the pilot assembly from either the thermostat, while others get it from the burners gas valve. Variations based upon the thermostat or the gas valve.

Bare in mind that conversions are not always as easy as they seem to be. Working with small diameter tubing for the pilot gas either from the gas valve or the thermostat, depending upon which system is used, requires careful work, attention to details and proper installation to avoid leaks and proper operations, etc.

This is about all the info I could possibly offer you.
Good Luck.
Tom_B
 
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Old 11-12-02, 05:12 PM
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There is one more small bit of information you could help me with. I just measured the output from the mini pilot thermocouple and it's about 20 mv and goes up to 22mv after 5 minutes in a flame. A local tech told me that I should be looking for 30mv +- 10%. Can you tell me if my reading would confirm that the thermocouple is defective. You said about 1/4v which would be 25mv, and I'm not sure what is good and what is acceptable in this case. If the mv were slightly under spec could that translate as a burner flame that is very low and doesn't get any higher, or does the ASO work in an off or on mode only.

I've found that I can put in a standard type pilot assembly and thermocouple for around $50-60 so I'm trying to ensure that it's the thermocouple that's defective and not the ASO valve.

Thanks for all the help, sorry to keep bugging you.

John
 
 

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