Convert NG to LP 1950's stove

eclecticcottage Posted By eclecticcottage, Feb 15, 2012 at 1:26 AM

  1. coaly

    coaly
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    The threaded connection looks like it has thread tape or sealant on it ?
    Brush it clean with a wire brush. No sealant is used on a flare since the angled end is the mechanical joint. The threads are straight, not tapered and only pull it tight. The threads are not used for sealing like on tapered pipe threads that require sealant. Tape on a straight flare or hose thread only binds the threads so you can't feel it tighten properly on the seat.
     
  2. eclecticcottage

    eclecticcottage
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    WIn :cool: We do have to adjust three of the burners, they are a bit excessive.

    cottage61.JPG
     
  3. eclecticcottage

    eclecticcottage
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    Still have to adjust the oven and broiler, we haven't touched that yet. Also...this one seems to put off more heat than the old Hotpoint. WOWZERS. And the burners aren't adjustable (like low, med, high) so there will be a learning curve there.

    But it's in.

    THANK YOU THANK YOU THANK YOU!!!
     
  4. coaly

    coaly
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    They are hot burners. There's no yellow, so they are fine. Notice the light blue flame down at the burner, then it becomes a darker blue secondary flame that mixes with others and becomes one. This is like adjusting a torch when you have a pencil tip light blue flame that becomes the larger secondary flame. When you set a water filled kettle on the burner, you'll notice the flame change. At the highest setting, you want the flames to come to the edge of the kettle or pan, not up the sides. That's wasted heat. My commercial Garland star shaped burners are 30,000 each. I'd guess yours to be 15 to 20,000 each? Maybe more.
    There's no way to tell without knowing the oriface hole size.

    Check above the pilot for soot in a day or so. Then periodically. If you see an accumulation of black soot, it's too big. People tend to adjust pilots too large. It doesn't take much. Depending on the cup the pilot sits in, the rule of thumb is to the top of the cup looking across the top of it. If the cup is low, the pilot flame should only be as high as the center of the pilot tube. (the tube gas goes from burner to pilot through to light burner)

    Let me know if you have problems with the oven. It should adjust the same way.
     
  5. eclecticcottage

    eclecticcottage
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    We did adjust the other burners a little. Two are perfect, one is pretty good and one is ehhh. It will take a little tweeking, but that's fine. The flames were wrapping up around the edges of our bigger pot on three if them, so we figured we should see if we could get them a bit smaller. After looking "under the hood" of the hotpoint I can't see why someone wouldn't want to work on this vintage of a stove-it's so much more straigh forward! Oh well.

    Is the oven orifice down in the oven? I haven't really looked for it yet, but I know It didn't look like it was up under the burner cover with the others.

    Oh and just for good measure since I kept posting pics before I cleaned under there...this is what it looked like after cleaning (without the burners or crumb trays in)

    [​IMG]
     
  6. coaly

    coaly
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    Yes, it's in the oven. The burner tube will be one piece like the top burners. Gas is admitted at the air intake / adjustment area, fuel mixes with air in the tube before coming out the holes. Sometimes the burner tube sits over the oriface and you need to remove the burner to tighten down the oriface. Others are far enough from the oriface to tighten it down wihtout removing the burner.

    Here's a few IMPORTANT things before you start trying to light the oven;
    I don't know the type of oven control this uses to ignite the main burner and be controlled by the thermostat without close ups of the thermostat control valve and pilot / burner.

    ** Open the top, and look carefully at the thermostat control for a little screw shank that sticks out with a cross piece like a T handle. (Or a T handle with only one side of the "T" like a motorcycle or small engine fuel shut off valve. It will have Nat and LP stamped on it, so you need to turn this adjuster over to the correct fuel. This changes the size of the oriface in the control valve so the "pilot control" is the correct size. **

    This could be the screw shown on picture #60. Somewhere on the control valve should be the adjuster that can be set to either N or P for Nat or Propane , or Nat and LP.

    This thermostat is a "pilot control" and is what keeps the pilot small to maintain a fire when oven is off or not calling for heat. When the T-stat is turned on calling for heat, the small pilot becomes much larger. That is what controlls the oven burner in this type of control. This larger pilot flame heats the oven safety valve capilary tube. The fluid in this tube expands and opens the oven main burner valve. (called a "safety valve") It takes time when the T-stat calls for heat and the pilot increases in size to heat the safety valve. 30 seconds to a minute for the oven valve to open. Make sure both the Nat / LP "switch" on the control and oriface is correct for LP before lighting. It takes time for the capilary tube on the safety valve to cool down to shut the main burner off as well.

    LP Gas vapor on a stove top is bad enough, but confined inside an oven can become much worse. Leave the door open until you're sure the burner is correct, lights smoothly, and burns blue.
     
  7. eclecticcottage

    eclecticcottage
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    I know it's a robertshaw (or so says the oven temp control knob), but that's about it. It's a match light oven, no standing pilot there. I will take a look tonight and post if we have any questions. :)
     
  8. coaly

    coaly
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    OK, that type without a standing pilot will hand light the main burner, and when it comes up to temp, the main burner shuts off and a bypass in the T-stat allows the main burner to go down to a very small flame. Almost little dots at each hole in the burner to just stay lit.
    That's the first type themostatic control of the oven. Then came standing pilot with safety valve, (like I explained in previous post) then electric spark, (DSI or Direct Spark Ignition) and now glow bars to warm the safety valve and ignite the oven.
     
  9. eclecticcottage

    eclecticcottage
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    Win x2! This was pretty easy actually. DH went over to a friends house to see if he had a spring for the carb on a little cultivator we picked up so I tackled it. The access for the orifice and the air flap are in the storage area next to the oven. The only thing with tuning the gas/air mix was waiting for the dirt to burn through after each tweak (yellow flames). And realizing I could check he flame via the broiler instead of leaving the "floor" out of the oven, lol.

    THANK YOU again! And we now have an oven for the first time here. YAY. Now we need to get an oven thermo and see if it's calibrated correctly.
     

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  10. coaly

    coaly
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    Yep, it's easy once you do it. The next one you look at may seem completely different, but the basics are still there.

    You're right, the yellow is from dust and dirt knocked loose in the burner tube or can even be contaminents in the air (dust from shirt sleeves) that burns as it goes through.

    Some oven thermostat knobs have a screw on the back that the center portion that goes over the valve can rotate and slide in a slot, so you hold the knob center still and turn the knob to put the degrees on the face where you want them. Some ovens with broiler door under them are supposed to be used with broiler door partially open for proper circulation. That changes the temp. too.

    Glad I could walk you through it.
     
  11. eclecticcottage

    eclecticcottage
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    Just popping back in to say we're still running the Bengal without issue. We use both the burners and oven regularly and it seems to use very little propane. I even found it a friend:

    [​IMG]

    that is a 1950's Norge Customatic, snagged it for $100. Runs super, quieter than our 200? Kenmore AND uses less electric than the (energy star rated) Kenmore too.

    Check out the egg keeper thingy:

    [​IMG]

    I couldn't stop there of couse, so I picked this up for $25:

    [​IMG]

    that is a 1960's era Kitchenaid 4C. Works great, just needed a serious cleaning.
     
  12. sunmtnforge

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  13. sunmtnforge

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    Hello-I have a late 40's Wedgewood stove set up for natural gas. I am running LP and will solder and redrill the orifices. Mine has 2 orifices per burner, one goes to a center ring the size of a dime, the other feeds the main burner (3 1/2" dia in the back and 4" dia for the front burners). I was planning on drilling around a #65 to start with but after reading your info it sounds like I might need a variety of hole sizes and would rather start small and bring them up to needed BTU's rather than resolder again after overdrilling.
    Also-I do not know what to do for the pilots as they appear to be tubing(sealed) with no apparent removeable orifice.
    ANY advice would be deeply appreciated Coaly
     
  14. coaly

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    Pilot line normally has what looks like a cap over the end of line where it attaches to pilot burner with smaller than a pin hole in the end. If you remove the line from pilot burner it may stick inside the burner and need to be pulled out of the pilot burner. Sometimes a wooden match pressed into the "cap" shaped like a tiny sewing thimble wedges into the oriface and you can pull it out. (1/8" lines) !/4" lines have a larger oriface (not hole size) that matches the line diameter. Normally a compression fitting that the ferule seals against the flared out end of the oriface. A pilot burner has a way to get oxygen to mix with the fuel just like a main burner. So the size of that oriface isn't as critical as a main burner. Normally simply adjust the flow on the pilot line. You should be able to follow the pilot line back to an adjustment screw that will adjust the pilot flame height as well as shut it off. (for pressure testing) If the end of the line looks like it is pinched shut to make the oriface, you may be able to shut the pilot off, and holding a match to the pilot slowly turn it on until it lights. If the pilot line connects to thermostat for oven pilot as well, there should be a screw to turn with arrow or pin pointing to Nat or LP that changes the pilot line flow with an internal oriface inside thermostat. You only want a small candle flame to prevent soot accumulation above pilot. If it has pilot tubes directing gas from burner back to pilot, the pilot flame should be no higher than the top of the tube height.
    If there is a tag on the range giving BTU of burners, I can give you the oriface sizes to achieve the proper BTU at your 10" W.C. operating pressure.
     
  15. sunmtnforge

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    Coaly-The only tag I am seeing is to the right of the magnetic valve. It says Wedgewood and the model or serial number. The writing is worn off but below that are numbers that were luckily stamped into the metal tag: 24000 9000 18000 not in a row but vertically. Because the (painted?) tag is worn I can't see what it said to explain the numbers. Do these pictures help? DSCN3346.JPG DSCN3347.JPG DSCN3348.JPG
     

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  16. coaly

    coaly
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    Pilots are all adjustable with the small screw on the line where they connect to manifold and T-stat. So you shouldn't have to touch those orifices.
    Can't tell if the top burner orifices are adjustable. It looks like the top burner orifices are adjustable by the threads showing where the orifices are screwed onto the valves. Remove burner from orifice and remove 1 brass orifice (cap) on burner valve. If there is a little needle sticking out of the valve that goes into the orifice hole, simply turn them down until snug so the needle protrudes more. This is the LP setting. Oven would be the same.
    If no needle you will have to change orifice size.
    I would imagine the oven is 24000 (#53 drill size)
    The top burners would be the two smaller orifices unless one burner is smaller on stove top for a simmer burner being the 9000.
    1800 is #55 drill size and 9000 is #64. These drill sizes are for an open orifice without needle that closes the opening to an adjustable size.

    The top plug on thermostat is a test port, and you should WD-40 the capillary line where it is green with corrosion behind t-stat. Carefully polish it with a rough rag or Scotch Brite with the WD to clean. It's just from dissimilar metals where soldered, but keep it clean.

    1). The appliance regulator will probably have a reversable cap you flip over for LP. Most are stamped on each side, so it may be stamped NAT now and when you unscrew the cap it will be stamped LP inside so LP is viable when you put it back on. This increases the spring pressure to open appliance regulator fully so the appliance gets full line pressure from low pressure regulator.

    2). Set LP/Nat screw on thermostat to correct position. (possibly behind knob on this thermostat)

    3). Verify orifice sizes.

    After regulator pressure is set and orifice sizes are correct;
    Close the pilot adjusters for the top burners AND close the pilot adjuster fully for the oven before turning on gas.
    Turn on gas and pressure test. Should hold pressure at 10" WC for 10 min. This shows no leaks in system as well as entire appliance.
    Light pilots by opening each pilot adjuster screw slowly with match held to pilot and adjust pilot burners to correct height.
     
  17. sunmtnforge

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    Coaly-There are 2 orifices per burner on this range. Both front burners are larger than the back burners. The one that feeds the large outer circle has a larger hole and what appears to be a 3 sided (disperser?) inside the tubing, I don't think that is the needle you are referring to. The one that feeds the small interior circle just threads onto open tubing and has a smaller hole. Here are more pictures- I am not sure where you are referring to "the top plug on the thermostat" is my screwdriver pointing to it? Is the screwdriver pointing to the screw I should tighten for the pilot? Broiler on the left and oven on the right side. I have an appliance regulator on the line in to the range I am replacing but I do not see one on this range. I am thinking maybe I have a lot of itsy bitsy different sized holes I have to break off bits in. Oh yeah and that center orifice is for the griddle (probably around the size of the broiler and oven orifices?) DSCN3356.JPG DSCN3361.JPG DSCN3360.JPG DSCN3362.JPG DSCN3358.JPG
     

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  18. coaly

    coaly
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    Yes that is the pilot adjustment and test port.

    The part of the burner that goes from orifice to burner is the mixing tube where air and fuel are mixed. Anything inside it creates turbulence for a better air/fuel mix. Newer ranges have an open tube and will not have that good quality of a blue flame as your burners.
    The needle would be inside the orifice cap, that is a part of the burner valve pointing into the orifice hole. You need to unscrew the orifice from valve to see it, or look into the orifice hole to see the tip. If it is there, when you turn the orifice down tight on the valve it will stick out of the orifice hole a little so the gas has to come around it. That closes the large size for NAT down to LP.
    The BTU totals are total of both burners combined into one. I didn't know you had a griddle, so those BTU numbers are probably rear burners lowest, front burners middle and griddle the highest. It won't matter if you have adjustable orifices. BTU is only needed if you have to make the orifice the correct size yourself.

    *** Nothing in your pictures is showing any antiquity that a current gas company shouldn't be able to convert. Are you sure it's not from the late 50's? Have you been operating it on Natural Gas? It doesn't appear to be as old as your claim having a thermocouple operated safety valve. Oven pilot size is critical to heat the thermocouple correctly. The threads under orifice in oven looks like the orifice can be simply turned down the same as a modern appliance. (adjustable orifice)
    If you are supplying your own fuel to an antique appliance I can help, (you assume all liability) but if this is connected to a supply from a gas supplier check with them for liability and what type certification they require to convert appliances.***

    An appliance regulator is only mounted to the appliance where it is connected to supply line. Any other regulator is a system regulator. It can be single or dual stage, both are designed to supply the correct pressure to appliance. With LP, the system regulator is the only pressure control since the appliance regulator is blocked open by the higher spring pressure. Converted to the Natural position, the appliance regulator keeps a constant low pressure to range if the supply pressure raises for any reason.
     
  19. sunmtnforge

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    Coaly-I was told by the seller that he thought this was a 1948, I don't know. I do not have adjustable orifices. I am confident that I can solder and redrill these if they are not readily available at reasonable cost. I will purchase the necessary bits but I prefer to get the hole sizes correct the first time. Yes I am supplying my own propane to this for a Mother-In-Law and it is the only gas appliance.
    Are the 2 units with the red ends (Robert Shaw) system regulators? They only affect the broiler and the oven. The pilots that heat the thermocouples for the oven and the broiler are both adjustable. Did you see the last thumbnail picture above showing where the orifices were removed? I am assuming the oven and broiler orifices are the same but I have not taken it off yet.
     
  20. sunmtnforge

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    P.S.- on the 2 orifices/burner that I took off, currently the smaller one is now sized to pass a # 76, the larger is plus # 61 (largest pin bit I have)
     
  21. coaly

    coaly
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    Got it.
    Here is a chart that shows Nat. and LP orifice sizes as well as drill diameter in thousandths. Don't worry about the BTU not exactly what you want. The chart is for 11" WC and you may have 10" or a little less during flow, so round up.
    http://andersonforrester.com/conversion-chart/

    The system regulator is at the LP cylinder valve. This reduces vapor pressure in tank to 10 to 11" W.C. (approx. 1/2 psi)
    The appliance regulator would be what the supply line or flexible connector connects to. I see non in the picture of safety valve showing flex connector.

    Are you referring to the safety valve with red button being a regulator? That's why I asked if you used this range with Natural Gas so I would know if you knew how to light it.

    No gas will flow through that valve until the red button is depressed. This manually opens the safety valve allowing gas to flow to oven pilot. (you can see the oven pilot adjustment screw that controls flow through the safety valve to pilot next to t-stat) Adjust pilot flame down before lighting since it is likely adjusted high for Nat. now. Hold match at oven pilot while depressing red button and the pilot should light when the gas gets down to it. Adjust pilot flame while holding button in. The pilot flame heats the upper third of the thermocouple causing dissimilar metals inside the thermocouple to touch. This creates a very low electric current flow up the thin wire to the safety valve. This current flow goes through a coil in the safety valve making an electromaget inside the valve that holds the valve open when you let go. So you have to hold the button 30 seconds to a minute after pilot lights to hold the safety on when you let the button out. If it goes out right away, you didn't hold long enough, or the pilot flame is not hot enough on the thermocouple (dirty pilot is the the usual case) or the thermocouple or coil in valve itself is bad. (min. 25 mv or 1/4 volt) These systems usually outlast the appliance. The parts themselves are not problematic. Usually gas flow or operator error. The red button also has to seat a steel pin against the electro magnet head inside. Some require a strong push before you let go to seat pin on magnet head. The steel pin has to contact the magnet head inside to hold it on when released.
    Us gas men use more electric meters for troubleshooting electric on "gas" systems than gas tools. The reason for the safety valve is if the pilot goes out the thermocouple stops producing voltage to the magnet coil and the gas flow is shut off. If oven thermostat calls for main burner ignition, there is no flow to main burner. With this type pilot, you can't have it burn too weak or too strong. (it will flame cut or melt thermocouple tip)

    If you follow line from the square valve with red label I think you'll find it goes to the oven main burner. That would be the oven control valve. (it gets gas flow from t-stat when calling for heat sensed by capilary tube)

    Look around for a bracket that may hold the orifices you need. They normally came with both for different gasses and may be hidden on a clip type holder somewhere ! On back or behind bottom doors ? It wouldn't surprise me if you found them somewhere on the range screwed onto threaded studs to store them.
     
  22. coaly

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    Some of those valve threads can get corroded so you may want to soak the orifice threads overnight with PB Blaster or penetrant of choice. It's not unheard of to break a valve removing an orifice. You can see how thin the soft brass wall is. Don't force them and work back and forth if necessary as they are removed.
     
  23. sunmtnforge

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    Well, I am very sad to say that I have taken all removable parts off and searched everywhere and underwhere to no avail trying to locate more orifices. The only questionable panel is pictured but does not have an obvious way to remove it, there are 2, on the outside wall that have a keeper at the top and a tab at the bottom. The ones on the inside wall have a screw, and inside appears to be hinge related (in my case broken springs)-refer to pics. DSCN3364.JPG DSCN3365.JPG DSCN3371.JPG DSCN3366.JPG
     
  24. coaly

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    The way orifices are sized in that case is with a tool that comes with an orifice kit that looks like a small center punch which has a round tip. You put the orifice over a metal rod that fits inside it and use the punch around the hole to close it up. They are made of a malleable material that is easily cold worked. Then drill to size. (normally hand drill with pin vise)
    You should be able to get door springs by length. Replace both to keep tension equal.
     

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