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Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 22040
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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Sears Natural Gas hot water heater pilot light going out and

Customer Question

Sears Natural Gas hot water heater pilot light going out and burner going out. New thermocouple new control valve. flame is eratic and orange . Tested thermocouple with voltmeter reaches 29 millivolts
Submitted: 2 years ago.
Category: HVAC
Expert:  airheatman replied 2 years ago.
Sound like either there is a blockage in the pilot tube orifice or gas valve is defective. I would start by removing pilot tube and cleaning the orifice.
Customer: replied 2 years ago.
I've blown through orifice and it seems clear
Expert:  airheatman replied 2 years ago.
Do you have a manometer or pressure gauge to test gas pressure into the valve
Customer: replied 2 years ago.
No but when pilot ignites it looks as big as it always has but just will not stay lit now (was staying lit and able to fire up burner which flame did not have good shape or blue color
Expert:  airheatman replied 2 years ago.
OK so you are saying that the main burner flame is what is erratic, not the pilot?
Customer: replied 2 years ago.
Yes when the burner was able to fire up yes the pilot shape was fine
Expert:  airheatman replied 2 years ago.
Let me ask you this. Is flame stable until blower starts and then jumps around?
Customer: replied 2 years ago.
There's no blower it's just a burner in hot water heater
Expert:  airheatman replied 2 years ago.
Duh. My bad. I am working with someone on a gas furnace also.THis may be a pressure issue then. Did it do exact same with old gas valve? And do you have other appliances that operate on gas and if so any issues with them?
Customer: replied 2 years ago.
yes old valve was going out also. Gas cook stove, refridgerator, freezer, are all working good.
Expert:  airheatman replied 2 years ago.
Does this model have an intake screen that may be dirty?
Expert:  airheatman replied 2 years ago.
http://i.imgur.com/CsMepoi.png
Customer: replied 2 years ago.
have checked screens at bottom of heater and they r clean. when we light pilot, then turn temp setting up till burner lights, it burns blueish and fluttery, then both burner and pilot go out.
Expert:  airheatman replied 2 years ago.
Being that you have already replaced valve, thermocouple and cleaned screen and we are pretty sure pressure is good, not sure of what else may be causing this.I will open to other experts to see if anyone has more ideas.
If no expert can help and you are unsatisfied, we can request a refund of your deposit.
Customer: replied 2 years ago.
ok, but in mean time, could u please make some educated guesses and/or suggestions.
Expert:  Rick replied 2 years ago.
Did you pull the burner and vacuum the air intake port under the burner? did you actually remove the burner and make sure there's nothing floating in the main burner tube that could block the orifice?
Customer: replied 2 years ago.
is that the round opening directly under burner? or all the little square ones?
Expert:  Rick replied 2 years ago.
It's under the burner on the end of the tubing. It has an ~ 1/8" hole in it. Usually has a hex shaped top. The only possible culprits based on your description are: lack of air (clogged intake opening under the burner), something floating in the burner tube that rises to block the orifice opening once the burner fires up or gas pressure issues. You can check the first 2 with common hand tools. You'll need a (pricey) gauge that can read in inches WC (water column) to check the gas pressure. If you don't find anything in the burner tube and you still have the same problem after vacuuming out under the burner then try pulling the gas piping apart. There might be something floating in the gas line. The last one is more likely if teflon tape was used on the pipe joints.
Customer: replied 2 years ago.
I replace thermocoupler then wife replaced valve, i will take apart and check lines. also just vacumed intake under burner and will check the 1/8 hole?
Expert:  Rick replied 2 years ago.
You have to pull the main burner completely out of the unit. It would be best to remove the orifice but that can be a challenge. If you can't get the orifice out then try blowing compressed air into the orifice hole.
Customer: replied 2 years ago.
have burner out. there is a 6" diameter hole with a fixed hard metal screen there of which i vacumed out. still not seeing orfice
Expert:  Rick replied 2 years ago.
Like I said before the orifice is on the end of the supply tube to the burner
Customer: replied 2 years ago.
i blew throght supply tube and there is no blockage, vacummed air supply opening and took off gas line to valve and found no blockages there either. should i now put it back together and see if maybe i sucked out impetimates and it may work?
Expert:  Rick replied 2 years ago.
It's worth a shot. Just to be clear, your description indicates to me that something could be floating around in the tube to the burner not a solid obstruction. When the gas flows enough gets to the burner to light it but then this possible culprit floats up to block that small hole in the orifice. There should be nothing in the burner tube. One other thing comes to mind but it's not very likely. Rheem (makes Kenmore heaters) has a device on some models between the end of the burner tube and the burner. If this device trips it blocks the gas flow but it's a positive shut off. I've never heard of one tripping partially (anything is possible). But if there's nothing between the orifice and the burner this does not apply.
Customer: replied 2 years ago.
its open
Expert:  Rick replied 2 years ago.
OK
Expert:  Rick replied 2 years ago.
I'd put it back together and give it a try
Customer: replied 2 years ago.
lit pilot, adjusted temp, burnner kicked on pretty as ya please, then everything went out. ?????what is going on?
Expert:  Rick replied 2 years ago.
What's the model number of your unit? Did you hear a click when it went out?
Customer: replied 2 years ago.
yes there was a click. Kenmore###-##-####
Customer: replied 2 years ago.
now pilot won't light
Customer: replied 2 years ago.
note: while checking line for obstructions earlier, i also heard a popping like noise when i opened and closed main gas line valve to heater flex line. wondering if that little in line safety check coupling that is right after shutoff valve could be worn out and maybe partially closeing of something that is disturbing gas flow to heater ?
Expert:  Rick replied 2 years ago.
The click is the gas valve shutting down. You said you replaced the thermocouple but this unit has a TCO as part of the pilot assembly. Did you replace the entire pilot assembly part #9003540?
Customer: replied 2 years ago.
yes. ignitor line, thermocoupler, and a silver line which may be the tco. also finnally got pilot and burner to go again, but as soon as burner lit, it all went out again.
Expert:  Rick replied 2 years ago.
I've got nothing else. Except that maybe the reason the TCO tripped the last time is still in place and that caused the new one to trip as well. This could be due to a blocked vent or an over sized burner flame due to excessive gas pressure.