RobertShaw BJ Oven Control

RobertShawDial

If you determine that your oven thermostat that doesn’t work, you have to replace it if you want a functional oven. It’s not really a DIY project, unless you have very specialized equipment. Just thought I’d let you know before you read anymore.

The only useful DIY info I can share with you is sharing how I found  the proper replacement thermostat and how I installed it. Also it is possible to send in a non-functional thermostat and get it rebuilt. That could be a better option if you cannot find the proper update to your model.

A critical component of my stove that didn’t seem to work right since I got it was the oven thermostat. Because I didn’t have any OKM stove documentation yet, it took me a while to realize that O’Keefe & Merritt stoves didn’t have O’Keefe & Merritt oven thermostats – they had RobertShaw brand thermostats.

Knowing that really helped reduce my confusion when reviewing search results for how the things were supposed to work, how much new ones cost, how many different models there were. Ah, the famous Robert Shaw thermostats. Nice, purely mechanical oven temperature regulators – no electrical hookup needed.

So back to my problem. My stove came with a sad, half broken Robert Shaw BJ model oven valve and thermometer.  How did I know? It did allow gas to flow when turned on, and it could stop the flow when turned off. When lit, the burner flame was low. Basic testing by PG&E and myself indicated the thermostat itself leaked gas from the front stem and near the back of the unit. Possibly enough gas was leaking from the thermostat to impact the amount getting to the burner? It’s biggest failure was the thermostat could not regulate the temperature. That meant the temp would continue to climb higher and higher, no matter what the dial was set to.

Time to play with the thermostat!  Now, I was told, advised, warned that these thermostats were not DIY items.  Not! Not! Not! No one said why, but all the experts made that fact clear. OK. Thanks for the heads up.

Did that stop me? Nope. I figured I had nothing to lose. Besides I HAD to give it a shot before laying out hundreds of dollars to buy a replacement for a feature I didn’t really need. I already had a great countertop digital microwave/convection oven.

Of course there was also that curiosity thing. 🙂

So I opened it up. Such fun curious internals. Lots of bits, pieces, gizmos and such.  First thing was to identify leak locations. I made gaskets for the unit that successfully stopped the gas leaks. I cleaned, lubed, adjusted everything I could. After that session, the burner flames were larger, which seemed great! Although I soon discovered the oven would get nice and hot, then hotter and hotter. It couldn’t hold a set temp. It’d just continually burn at max output. A pretty dangerous behavior – indicating the thermostat still didn’t work.

But at least I explored the inside. In fact, I accumulated and explored three or four more RobertShaw thermostats, all of which didn’t work. I still want to know what it takes to rebuild these things.

Pricing RS Thermostat Repair Options

Surprisingly, these little mechanical stove jewels and their updated cousins are still available but at a ‘sit up and notice’ wide price span of $150 – $650! Well ain’t that’s just grand. Best prices currently are at Patriot Supply.

My other option – send it out to rebuilt. That was actually no cheaper! The thing was, getting my thermostat rebuilt meant I would get the right/original thermostat for the oven. If I ordered one I’d have to make sure to get the right model. RobertShaw has been updating and expanding their line of thermostats since at least the 1940s.

But the oven gods had smiled upon me. A seller on ebay had a small collection of new RS oven thermostats for $85! Eighty five dollars and free shipping! I figured it had to be ones I couldn’t use. So I searched for all possible online sources. Incredibly, I actually found similar replacement models ranging from $200 – $600. That made it even harder to forget the $85 dollar ones. 🙂

The only problem – assuring what was for sale would be a proper replacement. My stove’s model was a “BJ”. The ebay models I found for sale at that time were BJWAZs; BJ replacement kits with VC4500-005, -006 units.

RSovenBJWAZ_ebay
eBay offering

Huh?

Don’t ask me. I didn’t name the things. But know this… There are a lot of specifications to these thermostat controls including;

  • switch position (left/right)
  • outlet position (left/right)
  • outlet diameter (1/4, 3/8, 7/16)
  • capillary length (36″, 48″, etc.)
  • dial rotation (left/right)
  • temperature range
  • rear housing (down/right/left)
  • switch terminal connections
  • mounting characteristics

So it’s important to know what model replacements will work for your stove. Here’s a link to a very helpful RobertShaw pdf. It’s a little much to take in at first. If you use a little patience and learn their lingo, it will really help you understand the thermostat market.

After lots of research, it seemed like the BJWAZ would really work as a replacement in my stove, so I finally ordered it, made a small piping extension since the outlet was on the left side instead of the right side, installed it, turned it on…

It worked!!! It worked beautifully, accurately. Hot damn!

RSovenBJWAZ1

RSovenBJWAZ2

 

 

Fruitless fun. This is the RobertShaw BJ thermostat, the model that was original to the stove. I took photos while taking it apart. I even made new gaskets for it to make it stop leaking gas. However, no amount of tweak, lube, cleaning, gasketing, etc. would get the thing to work.

RSoven_reassembled RSoven_opening RSoven_bothGaskets RSoven_manifoldGasket

 

45 thoughts on “RobertShaw BJ Oven Control”

  1. I have 3 original thermostats for the old O’keefe ovens.
    They are new, still in the box.
    I was in the appliance repair business for over 25 years, and have been retired for 20 years… they are still like new.

      1. I have a vintage 1960? Kenmore gas stove.the oven has stopped working since about a year. The pilot in the oven is on but when we turn the valve on no gas goes to the burner and we get no heat.I thought it might be the thermocouple but I can’t get the thermocouple unscrewed from the valve. Any help out there?

    1. Bill
      Do you still have the old oven thermostats? Am looking forBJ (I realize there are several versions)

      Thanks

      Bob M
      Alameda, Ca

      1. I have several, salvaged from various OKMs: several BJs, a BJS and a BJWA.. However, I’ve never tested them. I assume they don’t work, though. The oven therm on my first stove didn’t work. Luckily, someone on ebay was offering a similar enough model (a BJWAZ) for $70. Research indicated it would fit, so I took the chance and bought it. It fit!

        1. On your bjwaz, there are what appears to be electrical connection. Are these for the oven light switch? My old bjs model has connections on the very front, just shy of where the valve to the dial would go… I’m confused! Can’t seem to find what I need…

      2. I have a vintage 1960? Kenmore gas stove.the oven has stopped working since about a year. The pilot in the oven is on but when we turn the valve on no gas goes to the burner and we get no heat.I thought it might be the thermocouple but I can’t get the thermocouple unscrewed from the valve. Any help out there?

        My thermostat /valve is a Model BJ.

        1. Whoa, Jeanette! The sensor attached to the BJ thermostat isn’t a thermocouple; it’s the thermometer for the oven thermostat and it isn’t supposed to be removed. A thermocouple is attached to a safety valve, the thing with the red button. The other end of the thermocouple is aligned next to the oven pilot.

    2. Great info here, thank you! I broke the thermometer/probe that was exposed in the oven of my 1950s O’Keefe & Merritt. Do you know if I need to replace the entire thermostat to get it working again? I can’t seem to find anyone who specializes in antique gas ovens around here, do you think this project would be easy enough for a regular gas-focused repair person if I can find the appropriate replacement kit?

      1. Thanks! I hope the info helps you.

        If you’re referring to the sensor that hovers near the top of the oven cavity and connects directly to the oven temp control, then yes, you’ll need to replace the entire assembly $200-$400). If you’re talking about the thermocouple that sits next to the oven pilot that sits next to the long oven burner inside the oven, you can order just a new thermocouple. The other end of the thermocouple is connected to the safety valve (has a big red button on it). You can unscrew the thermocouple and easily replace it with a new one.

        Replacing the oven temperature control is more complicated. Problem is unless there’s a biz near you that specializes in vintage appliances, you’re just as qualified as a regular gas-focused repair person when it comes to replacing the oven temperature control. If you’re mechanically inclined, it’s not terribly hard. However, anytime one works with gas, there are risks if you don’t have the right equipment and understanding. If you can’t find a vintage gas repair soul, try a highly experienced plumber.

        Let me know which one is broken. If you have a Facebook account, post any photos there and we can go from there.

    3. I need A oven Control valve thermostat for a old o’keefe&merritt the model number is 420-10 oven20000 if you still have A thermostat for sale please contact me sbdvorak@gmail.com or call or text me back 772 532 0318 thank you hoping to hear from you

      1. Finding an original working oven thermostat is a challenge, unless it’s already been rebuilt. However, Robertshaw did produce replacement models over the span of decades. So there are newer models that could possibly work. That’s what I had to do. My first stove’s model was a BJ. It took me a little while to figure out that a BJWAZ was an appropriate replacement.

        You will need to go shop using all the control specifications I listed:
        – switch position (left/right)
        – outlet position (left/right)
        – outlet diameter (1/4, 3/8, 7/16)
        – capillary length (36″, 48″, etc.)
        – dial rotation (left/right)
        – temperature range
        – rear housing (down/right/left)
        – switch terminal connections
        – mounting characteristics

        And while not specifically mentioned, the controls overall size.

        1. I cannot find any document for RS replacement alternative to their BJS. I have a 6 burner, 2 oven and 2 broiler OKM stove… What I have seen is the BJFMA – or, 4510-007, that looks like it could work. Question is, does it matter which TS you replace on the stove as long as the pipes fit, and it seats correctly into the manifold? I guess, I’ll just have to bite the bullet and buy this and hope for the best. I wish the ebay people would understand that pictures of shrink-wrapped parts just don’t work for someone trying to match what they have!!

          1. Update.. I received the replacement TS, however it wont work because the plate the mounts on top of the manifold is too big for it. Plan B… found a stove sort of identical to mine on ebay for $200 bucks. Worth every penny, as I have not only replaced the upper portion where the clock and timer are, but all the springs, the valve that starts gas flowing (not sure what its called), chrome left and right covers, the little timer next to the last burner valve (doesn’t work well yet, but mine was completely rusted and useless), and hopefully, I can modify mine to accept the grillevator that doesn’t look used after 60 years. I’m learning, but very happy so far. Looks like my oven TS was working, but it was the gas valve thing that wasn’t which was why I couldn’t get the oven burner to light. Thank you for the inspiration!

          2. Be careful! I needed parts for my first stove. Once I realized I could get tons of spare parts by getting another stove, I couldn’t stop! I have rescued a bunch of stoves; some are in too good of a condition to part out, some were rusted out enough so that pulling parts was the only thing to do.

      1. The griddle knob is the same as the other cooktop knobs, unless you intentionally want something different. There are several different OKM knob styles. There are a couple where the bezel is directly attached to the knob with screws. There are a couple of styles where the bezel and the knob remain separate pieces with a disc spring that sits behind the knob. If you send a photo of the style you’d like.

        OTOH, you might be able to repair your knob if you use some epoxy putty. It’s a little work, but a more cost effective option. What would you like to do?

  2. Hi There!
    I am ecstatic to say today I am cooking with gas!! On my OKM vintage stove! I love your website and have learned way more today on your website than I have in the last two years since owning (haven’t even come up with a name yet).

    I was not at home when the gas was hooked up by our local professional (will call him tomorrow). Four burners and griddle work…yay, but the oven and broiler aka Grillevator do not. Do you think that is because of this thermostat? Daughter pointed to three items on the stove our pro told her may not be working. two look like your thermostat picture, and one is square marked general controls magnetic
    valve. I have a number of other questions, but will post in relevant sections
    thanks

    1. I’m so glad to hear that, Sue. You’ve made my week! It’s so great to learn when someone has decided to honor these stoves by using them. I’ll be happy to help you any way I can with your questions, provide recommendations, etc. I’d love to see a photo of your ‘to be named’ kitchen jewel. 😉

      Also, as a vintage stove owner, you might want to check out a Facebook group called Vintage Stoves. There are many vintage stove owners, fans and even a few awesome experienced folk. And if you have a FB account, you can upload photos for you and others to reference for questions and answers.

  3. Thank You so much! I am glad That I made your week!
    Just wait till you see the picture, she really is a spectacular & rare gem. I am not on Facebook (yet). Is it ok to email pic?

  4. another question. How do you remove a thermocouple to replace it from one of the BJ thermostats? I can’t seem to get the nut on the thermocouple to turn.

    1. Whoa, Jeanette! The sensor attached to the BJ thermostat isn’t a thermocouple; it’s the thermometer for the oven thermostat and it isn’t supposed to be removed. A thermocouple is attached to a safety valve, the thing with the red button. The other end of the thermocouple is aligned next to the oven pilot.

      1. Well, thank you very much for clarifying that issue for me! So I see the valve with the red button down near the broiler. How do I find the replacement thermocouple information?

        On another note, the lack of a working gas oven allowed me the opportunity to use the little electric oven on the left side of the stove. Made an ok pan of biscuits. This stove also has a rotisserie in the electric oven. I had no idea that duel fuel stoves were made back in the 1950’s. So neat!

          1. It’s a pretty cool stove. It has a fluorescent lit back and pink aluminum that was in style back then. It also has electric plug ins in the back and switches to move the power supply between the plug, the rotisserie, or the electric oven. The clock isn’t working, but I want to tear into it and get it refurbished. Pretty sophisticated mechanism.

  5. BJ oven control creeping? There could be a couple of reasons, either faulty th/stat OR more likely; a poorly adjusted “bypass”. This is corrected by one of two screws located just above the main tumbler as you look towards the valve from the front, with the oven control knob removed from the stove. One screw is for the pilot adjustment(right side), the other one is for bypass.
    How to adjust; as the heat rises and gets close to the temp you set it at, watch to see when the main burner flame starts to lower. From this point onwards, say five minutes, it should be on bypass. Simply observe the flame height, and see by turning the left screw if the flame increases or not. If you get an increase in flame that usually indicates the bypass works. Now, turn the oven control up 25 degrees and wait for the flame to come back down and if need be, adjust the bypass screw a wee bit until you get an even lower flame. Usually the flame is about 1/8 to a 1/4″ ,just enough to maintain your pre-set temperature.

    1. Wow, Robert! It’s great to come across someone who knows their stuff! I never knew what those little screws were for. You’re a jewel! While I haven’t had any trouble with my replacement oven control, it’s awesome you’re sharing this for anyone who might need to understand their control.

  6. I am trying to find the correct RobertShaw thermostat for my O’keefe and Merritt. the pdf link you have listed says the page is not found. the model # to my stove is 420-7. (i don’t think the thermostat on my stove is original. not a robertshaw) I cant really read the one my stove uses. any help you can give would be greatly appreciated.

    1. Hopefully together we can figure out what oven control you need!

      Stove model numbers with O’Keefe and Merritts doesn’t really help much. There are so many variations, it almost seems like the model number is really a serial number! 😉 Does yours look like this? http://www.dreamstoves.com/1951-okeefe-and-merritt-model-420-in-white.html

      What would really help is to see the spot where your stove’s oven control is located. The process of identifying the right oven control is dependent on a surprising number of critical factors. These include your stove’s oven features, the diameter of the gas supply lines from the control to the safety valve or oven burner (if the stove isn’t equipped with safeties), the amount of space the stove provides for the oven control, length of thermometer, preference for CW or CCW turn for temperature control, etc.

      As far as I know, most mid-century OKMs started with Robertshaw’s “BJ” oven control. Over time, features were added to the stove so the oven control ID gained all kinds of crazy ID extensions (like BJWA, BJWAZ). I believe you couldn’t go wrong simply getting what is called a “Robershaw BJ kit”. It’s the simplest control. But if your stove has limited space, or oven timers, you may need something a little more advanced or unique.

  7. Ms. McCrorey –

    Firstly, thank you for your blog/website/all of the time you have invested to assist other O’Keefe & Merritt owners/lovers. It is truly invaluable (far & away the most useful site/info on the web regarding OK&M).

    Secondly, I have owned & been running an O’Keefe & Merritt stove for the past 15+ years (I would/will not utilize anything else/less). Unfortunately, due to a recent move/change of location, I now no longer have natural gas available in my home/to my OK&M.

    Therefore, my only choice/option is conversion to LP/propane.

    I started off by purchasing 2 qty separate/different inline NG/LP regulators (one from the Old Appliance Club [for some ridiculously high sum/amount] & the other off of eBay [which I believe it is the exact same one/model you have pictured on your blog/website) & neither one of them work (when I install either/both regulator(s) on my inline LP/propane line, I seem to get no gas/propane to my OK&M [& yes, they are correctly flipped to the LP/propane setting]). When I attempt to get support/assistance from the Old Appliance Club, they are complete a-holes (please excuse my language, but these people are real jerks, as this is my 2nd extraordinarily unpleasant experience with them in the last few years) & any/all other appliance repair shops are universally/across the board absolutely unwilling to even consider having a look at my OK&M, or assisting me in troubleshooting the issue/problem (most tell me to get/buy a newer stove/range) ?

    So, I am now attempting to convert the old fashioned way (i.e: adjusting each/all orifices, pilot valves, etc.). I have successfully adjusted all of my pilots & cooktop burners (yes, nice all-blue flames, etc.). However, my Robertshaw Thermostat (which, I believe it is the same model BJWAZ as you possess/own) which I purchased brand new approximately 6-7 years ago for my OK&M, now appears to be leaking gas/propane out of the front/dial (which does not make any sense [at least to me], as when I unhooked my OKM from my old house/gas line, everything appeared to be functioning properly, with no leaks, but ?).

    Therefore, before I go shell out another $150-$200+ for another Robertshaw BJWAZ, I thought it would be worth asking you exactly where you created/placed new gaskets in/on your thermostat, which resolved/stopped it from leaking gas ? From the photos you posted on your blog/website, the only 2 gaskets I see/which appear to be created/added are:
    Gasket #1) The gasket which sits between the thermostat itself & the OK&M gas pipe (which I am certain is not my problem, as I have 3 qty separate original/Robertshaw gaskets, & have both tried/tested them all, & even gone so far as to fabricate a little metal plate, which seals off/isolates the OK&M gas pipe, conforming that my gasket is sealing properly/correctly), & Gasket #2) Gasket which sits between the front & rear 1/2’s/sections of the thermostat.
    However, my thermostat is leaking gas/propane from the front/stem area (you state that yours was leaking both from somewhere near the rear of the unit, as well as from the front/stem area) & I cannot see how it is possible that either one of the above 2 outlined gaskets could possibly resolve/rectify a gas leak from the front/stem area of the thermostat ? Am I missing something ?.. or, is it possible that you created/added 1 or more additional gaskets (which are not pictured on your website/blog, or I am too blind to see), which you believe resolved/rectified the gas leak from the front/stem area of your thermostat ?

    Any help/assistance/guidance/insight you can provide, would be very much appreciated.

    Thank you (in advance) for your time.

    Mr. Darling
    Seattle, WA

    1. Very, very impressive, Mr. Darling. You’ve done nearly everything I could think of WRT troubleshooting. And a total congrats on adjusting all the orifices to adapt to LP!

      While I remember, let me suggest you talk to a shop that specializes in gas appliances like propane grills, gas stoves, furnaces, etc. A competent shopkeep should understand the basics of what you’re trying to accomplish. You don’t need a vintage stove expert for dealing with those regulators. It could be the regulators you have respond to different/higher pressures than what you have available. (Just a guess). I haven’t dealt with them, but you might get some help from https://www.thegrillfather.com/products/accessories-bbq-supplies/bbq-grill-parts/misc-grill-parts/gas-grill-regulators-and-conversions/

      OK. I made my gaskets with a tan gasket sheet from an automotive supply shop (Fel-Pro Karropak Tan Gasket Sheet Material). You don’t need much, so hopefully you can purchase a single sheet instead of a huge roll. But the material isn’t expensive. http://www.autozone.com/sealants-glues-adhesives-and-tape/gasket-material/fel-pro-12-x-36-x-1-64-in-gasket-material-sheet/297302_0_0/

  8. I have an old O&M and recently the oven pilot has almost disappeared. It is extremely low. The oven doesn’t fire up, which I assume is due to the low pilot. I tried turning the little screw on the pilot line where it connects to the main gas line with no change (other than turning it off completely). Any suggestions on how to solve this problem?
    Thank you in advance….great website

    1. If the flame cannot reach the proper size, my first assumption would be the line itself has too much debris in it. Natural gas is sometimes dirty. You should remove the tube and try to run a wire (gauge 16 or 18) through the line and tap it to see if anything comes out. That might solve the problem. The other thing to check is in the base of the pilot. There’s a nearly microscopic hole in the base of the pilot. It might be partially clogged. It’s sometimes made of very thin metal so treat it gently. And don’t make the hole larger. It’s that size for a very good reason.

    1. I purchased a 3-5 generations newer thermo oven control model to replace my original Bj. However the calibration procedure was the same.

      The procedure I did is documented in the installation instructions that came with the unit. It requires using an independent and accurate oven thermometer.

      Basically, the oven control is set to a specific value (like 350). The independent thermometer must be placed in the oven’s sweet spot. Once the oven is turned on, allow it 10-20 minutes to stabilize on its heat setting. Check the thermometer to see if it’s reading matches what the oven control is set to.

      If it doesn’t, one pulls the oven control dial off. Underneath, is tiny dial with markings which represent 25 degree temperature increments. If the oven is well below the 350 degree temp, the tiny dial should be adjusted up (+). Then reheated to note the thermometer’s reading. All of this is repeated until the oven control dial setting matches the thermometer’s setting.

      If your oven’s control is similar, that’s what you would need to do. The most important thing you need to do is obtain a very accurate thermometer.

      1. Thanks for the information.

        I took the oven dial off and at the bollom of the tiny dial it says marks are 25 degrees. So it would seem to be the same procedure.

        BTW, our cooktop burners are completely different from the ones on your Lucy.

  9. Mr. Darling;
    I don’t yet own a classic O&M stove but I am in the process of purchasing one. Many years ago I installed gas-fired swimming pool heaters in the Southern California area. The shop I worked in was one of the few that specialized in natural gas-propane conversions. The nominal line pressure for a natural gas fired appliance is 0.27-0.29 psi. The nominal line pressure for a LP gas fired appliance is 0.36-0.40 psi. It doesn’t seem like much of a difference but it really is Of course gas line pressure is measured in column inches of water but I did the conversion to make it easier for most to understand.
    After installing a heater and making all of the required conversions the last thing we did was use a slack tube manometer to measure the pressure of the incoming line at the appliance. It was not uncommon to find the LP regulator at the tank to be out of adjustment and always on the high side at that. If you have not already done so I would suggest that you find a shop that can make a line pressure reading at your stove inlet line using a manometer to get an accurate reading on exactly what the incoming line pressure is. You may find that the regulator at the tank may need to be adjusted.
    I do know that older gas appliance valves designed for natural gas were not manufactured to tolerate the higher working pressure of liquid propane. Hope this helps.

    1. Whoa! Most of what you wrote is beyond my knowledge. 🙂 However, while I believe that vintage valves may not have been designed with propane in mind, I’ve come across many who’ve converted to LP from NG without incident. Unlike some of the newer gas stoves, the older valves are highly adjustable. And since they’re brass, they’re easily brazed shut to make them ready for redrilling smaller orifices.

      And if there’s a need to check the gas pressure, gas suppliers (i.e. PG&E) will likely visit to do an eval and test.

  10. I’m working on a similar stove as yours and struggling with oven thermostat right now. I found the refurbished model for $300 and the new ones on patriot supply for around $150 but according to the lady selling the refurbished one, my original knob will not fit on the new version thermostats. Did you find this to be true? It looks like you have the all white robertshaw knob on yours but the kit you purchased came with a white and silver version. Any info you have would be helpful! I also skimmed the comments on here and saw some people mention having extra thermostats which I would be very interested in buying! Mine is the same as what yours was, robertshaw bjwaz or 4500. Thanks for your help! This blog helped me a lot through my stove restoration 🙂

    1. Replacing the Robertshaw oven control is a little tricky. The space where the thermo control has to fit pretty much determines which models will work and that space is tight. And you need to match the knob to the control. Some oven control kits come with the proper knob. BJs aren’t made anymore, but there are similar enough newer models being made. Problem is not too many people understand what to look for.

      You will need to shop by specifications. IOW, things like an outlet diameter of 7/16″, capillary length of 3-4 ft, temperature range (low…250 – 550…broil), sensing bulb (3/16″ x 11-3/16″), rear housing (left, right, down), mounting opening diameter, etc.. This page is an example: https://www.johnstonesupply.com/storefront/product-view.ep?pID=F16-643

      Then if you decide to install it yourself, make sure you have a way to test for gas leaks. And you will need to calibrate the control, but calibration is easy.

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