Tip & How-To about Water Heaters

Trouble shooting common gas water heater lighting problems

This covers just the basics on no burner flame or pilot outage issues on standard tank gas water heaters and does not pertain to tankless or instantaneous heaters. As always, safety first; if you do not understand what you are doing, do not attempt to make repairs on your own. This is just a guide to help you figure out what may be wrong.

1) Let's take care of the obvious things first. If you have a propane gas water heater, make sure you are not out of gas! Go to the tank, lift the lid, look at the % gauge. If it's pointing at 5% or less, you may be empty or about to run out of gas. If it says you have plenty of gas, make sure the gauge is not sticking and bang the lid down. If the gauge drops down to 5% or less, order a gas delivery.

2) Remove the panel on the water heater to view the burner. Is the pilot still lit? Yes, then make sure the control knob is in the "ON" position. Also make sure the temp dial is not on "Vacation" setting or set at a very low temp setting. Typical dial settings are at medium "arrow" selection or "A" selection.

3) Is the pilot flame out? If you smell gas, do not attempt to light. Turn gas off at shut off valve on gasline to water heater and call your gas co. Otherwise, follow the manufacturer's lighting instructions on the water heater to relight. Pilot still won't light? Then you may have a dirty pilot orifice that needs cleaned. Or if you were out of gas and just got filled, you may have air in the lines and lighting the pilot will take longer than normal to light. It's best to have the gasman light this when he is there to fill your tank. It's also possible you have a control that is locked out or defective, which will require a serviceman to repair or replace the control.

Let's say you get the pilot flame lit. When you release the button, does it stay lit? No, then you might not have held the button down long enough, Try again. Still goes out? Is the pilot flame a strong blue color and actually making the thermocouple red hot? If so, and it won't stay lit, replace the thermocouple. Or is it a lazy yellow flame? If so, it may have burn't the tip off the thermocouple and it will need to be replaced. This condition is caused by a dirty pilot orifice, which will need to be cleaned with a broach to prevent it from ruining the new thermocouple you install.

4) Ok, let's say you relight the pilot and get the main burner to light as well, but later they both go out again. This only happens, of course, after the service tech has left. With it still off, get a flashlight and look inside the access panel in the area above the main burner? Do you see a lot of black soot build-up? If so, this make be causing your problem. Have your water heater serviced. If no soot, then check for blockage in your vent. Look for a bird nest or even a dead bird. Your vent cap is either going through your roof or through a wall to the outside. You'll need a ladder to check either. If it has bends and elbows, check those out for blockage too.

5) No blockage? Sometimes a vent is installed wrong (like under an eave) or you are getting a strong down draft. Make sure your vent cap is still attached on top of your vent too. Strong winds can blow out the pilot flame.

6) Here's another test you can do, if the pilot and burner shut down. Relight it as you did before and with the burner lit, reinstall the access panel. Now light a match at the draft diverter (standard water heaters have these on top which connect the water heater to the venting) Blow out the match near the edge of the draft diverter and watch where the smoke goes. (Shining a flashlight there also helps you see the smoke better) If it gets pulled into the draft diverter, it's working properly, pulling outside air in. If the smoke gets pushed out, you have a drafting problem. To make matters worse, you are also allowing carbon monoxide into the home. Have your water heater serviced immediately. I also recommend having a carbon monoxide detector located on every level in houses that have gas or oil appliances.

These are just a few ideas to help you figure out your common lighting issues. There are other issues that I did not cover, which may require a repairman. I hope you find these useful. If you still have concerns, please ask away! That's why we are here!

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1 Answer

the pilot won't stay lit on gas hot water tank.


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

Sep 21, 2011 | Water Heaters

1 Answer

The pilot light is out on the water heater. It will not re light using the posting directions. this happened a while ago and I called a tech. They were able to easily fix. There is some little thing that I was not doing. But of course I cannot remember. Any ideas on what to do? Thanks.


Better description is needed. Add a comment.
Do you have tank or tankless water heater?
What brand heater and what model shows on label?
If tank water heater, what does gas control valve look like? Is it electronic?
Open following link to help identify tank-type gas valve.
http://waterheatertimer.org/How-to-adjust-water-heater-temperature.html
Does pilot light start up and not stay lit, or is there no flame whatsoever?
What color is the flame?
Are you using piezo igniter or a match to light pilot?
Is there a power vent sitting on top of unit?
What happens when you get more fresh air to unit?

1) Maybe the thermocouple is bad. Or thermocouple is mis-aligned and not sitting in the flame.

2) Probably the technician should have cleaned the combustion parts.

3) Tank-type and tankless water heaters require cleaning on a yearly or semi-yearly basis. This action prevents lighting problems, and help prevent ECO events and that require replacing gas control valve.
Cleaning and general service including cleaning burner, cleaning air intake if that applies, checking for proper venting and vent obstructions, adequate air supply, backdraft, testing thermocouple etc.

4) IF you have tank-type water heater, and do not have electronic gas valve or power vented water heater, the following troubleshoot walk-thru is very good:
http://waterheatertimer.org/pdf/Pilot-outage-troubleshooting.pdf
Example photo showing parts for gas control valve.
http://waterheatertimer.org/images/IMG_9146-gas-control-thermo.jpg

Add a comment for more help

Sep 13, 2011 | Water Heaters

1 Answer

pilot will light, burner lights stays on for a while probably till it reachers temp then pilot goes out, its a rheem gaurdian 40 gal


This covers just the basics on no burner flame or pilot outage issues on standard tank gas water heaters and does not pertain to tankless or instantaneous heaters. As always, safety first; if you do not understand what you are doing, do not attempt to make repairs on your own. This is just a guide to help you figure out what may be wrong.

1) Let's take care of the obvious things first. If you have a propane gas water heater, make sure you are not out of gas! Go to the tank, lift the lid, look at the % gauge. If it's pointing at 5% or less, you may be empty or about to run out of gas. If it says you have plenty of gas, make sure the gauge is not sticking and bang the lid down. If the gauge drops down to 5% or less, order a gas delivery.

2) Remove the panel on the water heater to view the burner. Is the pilot still lit? Yes, then make sure the control knob is in the "ON" position. Also make sure the temp dial is not on "Vacation" setting or set at a very low temp setting. Typical dial settings are at medium "arrow" selection or "A" selection.

3) Is the pilot flame out? If you smell gas, do not attempt to light. Turn gas off at shut off valve on gasline to water heater and call your gas co. Otherwise, follow the manufacturer's lighting instructions on the water heater to relight. Pilot still won't light? Then you may have a dirty pilot orifice that needs cleaned. Or if you were out of gas and just got filled, you may have air in the lines and lighting the pilot will take longer than normal to light. It's best to have the gasman light this when he is there to fill your tank. It's also possible you have a control that is locked out or defective, which will require a serviceman to repair or replace the control.

Let's say you get the pilot flame lit. When you release the button, does it stay lit? No, then you might not have held the button down long enough, Try again. Still goes out? Is the pilot flame a strong blue color and actually making the thermocouple red hot? If so, and it won't stay lit, replace the thermocouple. Or is it a lazy yellow flame? If so, it may have burn't the tip off the thermocouple and it will need to be replaced. This condition is caused by a dirty pilot orifice, which will need to be cleaned with a broach to prevent it from ruining the new thermocouple you install.

4) Ok, let's say you relight the pilot and get the main burner to light as well, but later they both go out again. This only happens, of course, after the service tech has left. With it still off, get a flashlight and look inside the access panel in the area above the main burner? Do you see a lot of black soot build-up? If so, this make be causing your problem. Have your water heater serviced. If no soot, then check for blockage in your vent. Look for a bird nest or even a dead bird. Your vent cap is either going through your roof or through a wall to the outside. You'll need a ladder to check either. If it has bends and elbows, check those out for blockage too.

5) No blockage? Sometimes a vent is installed wrong (like under an eave) or you are getting a strong down draft. Make sure your vent cap is still attached on top of your vent too. Strong winds can blow out the pilot flame.

6) Here's another test you can do, if the pilot and burner shut down. Relight it as you did before and with the burner lit, reinstall the access panel. Now light a match at the draft diverter (standard water heaters have these on top which connect the water heater to the venting) Blow out the match near the edge of the draft diverter and watch where the smoke goes. (Shining a flashlight there also helps you see the smoke better) If it gets pulled into the draft diverter, it's working properly, pulling outside air in. If the smoke gets pushed out, you have a drafting problem. To make matters worse, you are also allowing carbon monoxide into the home. Have your water heater serviced immediately. I also recommend having a carbon monoxide detector located on every level in houses that have gas or oil appliances.

These are just a few ideas to help you figure out your common lighting issues. There are other issues that I did not cover, which may require a repairman. I hope you find these useful. If you still have concerns, please ask away! That's why we are here! Douglas

Sep 02, 2010 | Rheem Water Heaters

2 Answers

The Pilot burner flame is large & yellow


the pilot is getting too much air and is an indicaiot of dirty or air/ fuel ratio imbalance. The pilot is wimpy and the thermocoupler has alot to do with the gas . Make sure your thermocoupler is on the tip of the flame. You may end up replacing it. because it is showing signs of eminnt failure. When it fals your curners won't fire up. Good luck.

Jun 09, 2009 | Bosch AquaStar Propane Tankless Water...

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