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Ao smith pilot wont light.

sooperbsooperb Member Posts: 5
Hello, I have an AO Smith GCV 40 water heater.

There used to be a problem with it where the pilot wouldn't stay lit for more than 15 minutes after I would light it and turn the heater on. I would keep lighting the pilot manually to get hot water when needed.

One day it took me 10 minutes to light the pilot which was strange as it never took more than 2 minutes at the most. The next day the pilot just wouldnt light but the Piezo igniter was sparking brightly as usual. At this point I decided to finally fix it.

I replaced the thermocouple, the pilot gas line, the igniter line and the igniter switch which is almost everything.

The igniter is still getting a great spark but its almost like the pilot is getting zero gas. I am pressing the pilot button for a minute before clicking the igniter for a whole minute afterwards with the pilot button still depressed and still i am getting no pilot light at all.

Is there something I am missing here?
Please help.


  • unclejohnunclejohn Member Posts: 1,572
    The pilot tubing may be blocked or the air filter is clogged. Yes it has a air filter somewhere.
  • sooperbsooperb Member Posts: 5
    The Pilot tubing is clear for sure. I checked that as soon as I received the new parts to compare with the old ones.

    Theres a filter disc that I vacuumed that's located under the spot where the burner sits. I also cleaned uderneath the heater.

    Does the Thermostat box need to reset or something to allow gas to pass through it freely?
  • Tim McElwainTim McElwain Member Posts: 4,373
    Can you light it with a match? Then you need to take millivolt readings the procedure for that is available here on Heating Help if you are interested in attempting that.
  • Empire_2Empire_2 Member Posts: 2,343
    edited December 2015
    All pilot's have an orifice and it IS more than likely plugged. Nobody cleans them anymore and that is usually the cause of problem outages. The orifice hole is very small and can be cleaned with the single wire from a wire brush. This is the answer without having a pilot orifice bit set.

    Mike T.
  • sooperbsooperb Member Posts: 5
    The orifice hole is clean and clear. In fact the pilot orifice from the replaced assembly was clean and clear also.

    I'm thinking about cleaning the drip leg in hopes the debris blocking the gas from circulating to the valve box.

    If cleaning the drip leg doesnt work then I guess it gonna need a new valve box.

    What could stop the gas from reaching the pilot when the line is clean, the pilot button is depressed for 60 seconds and the igniter is sparking?

    The gas is reaching other heater with no problem. It just seems to not reach the water heater.
  • STEAM DOCTORSTEAM DOCTOR Member Posts: 1,167
    Might be an air issue or could be clogged orifice. Try lighting with burner not under water heater. Be very careful. If it lights then you know that there is an air issue.
  • Robert O'Connor_12Robert O'Connor_12 Member Posts: 724
    You must first establish whether or not the pilot is getting gas at all. Can it be lit with a match? If so, does it stay lit?

    Robert O'Connor/NJ
  • sooperbsooperb Member Posts: 5
    Thank to everyone for the input. I came down stairs to check for gas leaks and decided to try to light it while I was down here and poof, it lit up.

    I dont know why but the gas smell was strong. I turned EVERYTHING off. After a couple days I lit it again with no gas smell.

    The thing now is that when I look into the window the igniter tip is red hot,is that normal?

    Also the heater is screeching loudly and has been geating for a long time now. How long is too long to heat up 40 gallons?
  • Empire_2Empire_2 Member Posts: 2,343
    edited December 2015
    Probably from years of calcium build up is the sound you may be hearing. It will take some time to come up to temp. Q: you stated that the orifice was clean and clear......? How did you determine that if I may ask? Small hole and does not take much to block it from normal usage especially when it get older.
  • sooperbsooperb Member Posts: 5
    Well I knew the assembly was clean and clear because I took the whole thing apart. And you could see through it.

    I even put it back together and used an electric air pump to connect with the other end and blast air through the whole line,orifice and pilot.
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