Since it has turned cold my flame on cook stove has yellow flame

Is flame clear blue or yellow?
Yellow flame, clean the flame arrestor screen
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html


Flame is blue:
Low gas pressure.
Bad gas control valve.
Dirty combustion parts.
Clean the water heater parts and catch up on maintenance.-
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following links:
http://waterheatertimer.org/How-to-light-gas-water-heater.html
http://waterheatertimer.org/How-to-install-gas-water-heater.html
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html
http://www.thetankatwaterheaterrescue.com/forums/forum3/
Reliance is made by AO Smith company, and air intake located on bottom of unit.
Make sure you have adequate incoming air and vent is working.
Remember, the pilot is located upwards from the viewing sight-glass, so it is sometimes difficult to see pilot.
Pilot flame must burn clear blue, with bits of yellow and red. Yellow flame means inadequate air supply or venting.

Gene
h

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Make sure thermocouple tip is seated inside the burner flame.
Make sure thermocouple is not overtightened. Finger-tight + 1/4 turn.
If the pilot lights, then ECO energy cut off is not tripped, but gas control valve might be bad.
Check color of pilot flame: it should be strong and clear blue.
If pilot flame is weak, or color of flame is yellow-orange: Clean pilot orifice and burner and combustion parts on yearly basis.
Clean air intake screen if applicable.
Increase air supply to water heater. Open a window and see what happens.
Check for adequate draft going up chimney using match under vent hood to see if smoke drafts immediately upwards.
Bleed air out of gas line.
Check gas pressure.

Open following links for troubleshoot resources:
http://waterheatertimer.org/pdf/Pilot-light-will-not-stay-lit.pdf
http://waterheatertimer.org/pdf/Pilot-outage-troubleshooting.pdf
http://waterheatertimer.org/pdf/Vent-spillage-test-atmospheric-gas-water-heater.pdf
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

If it's an Atwood and just recently started burning a yellow, higher flame, look closely at side of fitting where the pilot tube is attached to mounting bracket. You should see a very small hole in the side of that fitting. Take a paper clip, or something as small in diameter, and poke around inside that hole to clean it out, or shut pilot off, and use compressed air, to blow into it, to clean it out. Now re-lite your pilot and see if you have a nice blue flame now. That little hole is your air mixture for the pilot and sometimes debris clogs it, thus causes (rich mixture) yellow/red flame, which will also cause soot build-up in the chamber, or even on outside cover. Let me know if that cures it.

It sounds like there is air in the line, so open the gas line just a little for a few short seconds to let some gas out, after that, keep the one red dial on pilot then turn the other to about medium. Light the pilot by depressing the red button, then once the pilot is lite, continue to hold the red button for about 1 minute, Once that is done slowly release the button and then turn the dial that is set to pilot to on position and give it about 1 hour to heat up

The pilot light is working so you know you have gas but you also know that the gas is not coming on. The pilot flame should be bright blue with the tip of the flame having a ting of yellow. A yellow flame is caused by a dirty pilot tube tip. Split flame is caused by dirt in the pilot tube. If the flame is not hot enough it will not tell the thermocoupler to turn the gas on. If the thermostat has not been moved and is still at the correct setting then I would suspect the thermocouple is bad. The thermocouple is mounted right next to the pilot light. It senses if the flame is hot enough for the gas to come on. If the pilot flame is not touching the coupler then it will not allow the gas to be turned on to the burner. Check the thermocoupler and see if the flame is touching the probe on the end. If not adjust it until the pilot flame is touching the coupler. If the flame is properly adjusted then replace the thermocoupler but shut off the gas supply before doing so. It will look like this.

Thermocouple. cannot be tested get new & replace. They are not expensive

Look and see if your pilots flame is touching the themocoupling ,if it isnt then cleane your pilot orfice.If that dosnt work replace thethermocoupler.I would also check the draw. Hold alit match or a cigerett up to the draft diverter (the air space between your heater and the vent. If it dosent draw the smoke up the vent it meanes your vent is stoped up or you need to raise it.

The question is? I'll assume you cylinder is the water heater, right?
On the heater (water) you will find or see the red controls and a sheet metal cover over a hole. Remove the cover and this is where you light the pilot light. Press down on the red dial and turn it to pilot. In that position you will be able to press the red button . Geyt a long match or bbq lighter, then, holding down the red button dow for a minute or so and place a match or lighter into yhe area where the lines go The flame will catch the gas and lite the pilot if yo simply move your glame around. When the flame catch on the pilot, continue holding the button down for sveral minutes until the buld the flame isheating gets hot. Then release the buton and turn the main dial to on. The main burner should fire up. If not, and the pilot goes out, repeat the process. The bulb in the pilot flame is a thermocoupler that shuts all gas off if it doesn't detect a pilot flame, so hold the button down longer. If the pilot goes out when you release the button, The thermocoupler is no good and needs replacing. Good Luck_Ned_

The steps involved can vary slightly depending on your furnace model and pilot valve type, so if possible try and find the instructions inside the furnace door cover or in the instruction manual. This is for a gas fired furnace, but applies to any gas-fueled appliance including water heater. Two of the most common types of pilot valve body assemblies either have a red reset button and a gas valve or no reset button and a valve knob that can be depressed. But whichever type you've got, if you have an older model furnace with a standing pilot (flame is lit all the time) then this is the basic procedure.

• Turn you thermostat to 80 degrees or to a setting that will demand heat. Make sure the thermostat is in "Heat" mode.
• Go to the furnace and find the pilot valve. The pilot valve body is a box shaped device into which the main gas line will run and is located near the gas burners. It will usually have a gas **** or valve knob that reads "On, "Pilot" and "Off." Locate this gas **** or knob.
• Turn the knob or gas **** to the "Off" position and wait about 3 minutes for any residual gas to clear away.
• Find the pilot. It's located near the gas burner tube assembly in the furnace.
• Get your match or lighter ready. Sometimes the pilot is hard to reach. If possible, try and use a long fireplace match when you light it. If you don't have a fireplace match then a butane BBQ grill lighter works well too. If you don't have that, then you can fasten a match to the end of a stick when you light the pilot

• If you have a pilot with a red Reset button, turn the gas valve from "Off," to "Pilot."
• If you have a pilot with no red button, turn the knob from "Off" to "Pilot."
• Place the lit match or ignited lighter tip at the pilot and depress and hold the button or depress the knob as appropriate. Depress the button or knob for about 30 seconds. This maintains gas flow to the pilot until the thermocouple gets hot enough to open the main gas valve.
• Once the pilot stays lit, slowly release the button or knob and turn the gas **** or knob from the "Pilot" position to the "On" position. This will ignite the burners and keep the flow of gas supplied as required for the burners as called for by the thermostat.
• If the burners fail to ignite then it may be because the thermocouple did not get hot enough to open the gas valve. Wait a few minutes and then repeat the above procedure. This time hold the red reset button or depress the knob for about 45-60 seconds.
• Once the main furnace burners ignite, adjust the thermostat to the desired setting.
• If you've followed the previous steps on lighting the pilot and it still does not light after, or will not stay lit, then you probably have a problem with the thermocouple or an adjustment needs to be made to the pilot. You'll need a furnace service technician to replace or repair these parts. You may find that the pilot lights, but it is an anemic looking flame. That's a different problem we'll look at in the next section.
  
• If the pilot lights but the flame is a weak yellow flame, it will not get hot enough to heat the thermocouple to its set point allowing the gas valve to open.
  A natural gas flame should be a bright blue with the tip of the flame having just a tinge of yellow. A propane flame should have a bluish green flame with a tinge of yellow at the tip. The flame should be strong enough to hit the thermocouple tip about 1/2 inch from the tip end. If the flame is weak or shaky looking, check to see that a breeze or draft is not blowing on it. Adjusting the Flame
  There is usually a small screw on the pilot valve body that will adjust the flame. You may have to refer to the manufacturer's instructions to find the screw. Turn the screw as needed to adjust the flame throw. Yellow Flame
  A yellow flame is caused by lack of air and incomplete combustion. It can be caused by a dirty pilot tube tip. Split Flame
  This is caused by dirt in the pilot tube. Take a needle or small nail and gently clean the tube. Flickering or Wavering Flame
  A flame that flickers is usually caused by a draft.
  

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