Why pilot light on my water heater goes out

I have been having the same problem with my hot water heater and have had several people out to check on it and even have replaced the hot water heater a couple of times. It is in a closet in my garage and works great all year long and when it freezes the pilot goes out. So my solution has been to open the closet door during winter months and I have not had any problems with it since then. I'm not a expert but its obviously not getting enough air in the cold times. Every year I talk about putting door vents on.

If a pilot light goes out after burner is lit there is, more than likely a pressure problem and it is usually at the regulator. I would check the vents on the regulator to make sure that they are not clogged. Wasps love to build nests there. Usually find mud packed in there causing the reg. to fail. In cold weather there can be water in the regulator that has froze. Make sure that the regulator is protected from water and that all vents are facing down. If everything checks out here the next thing can be a clogged pilot burner orifice. These usually need to be replaced these days. You can't just poke a wire through the orifice. Can also be a clogged pilot burner supply line. disconnect the line and blow it out with air. Should be done by a qualified tech. Adjusting the pilot flame up is usually a quick fix and I wouldn't recommend doing it unless a qualified tech is going to check it out after.

Did you check the flame assessor, it might be dirty and needs cleaning. Also, check to make sure nothing is blocking the flow of oxygen to the pilot light and combustion chamber.

Besides the thermocouple that has been replaced, there could be two other reasons for this problem.

1) The pilot orifice could be clogged. To fix this problem, turn off the gas to the furnace and shut off the circuit breaker that provides power to the furnace. Then take a thin piece of wire and poke it into the tiny opening where your pilot flame normally burns. This will push out any debris/ash that may be clogging it.

2) The pilot flame may need to be adjusted higher. Some water heaters have a flame adjustment screw that can be turned to adjust the flame. Refer to your owner's manual but usually this screw can be adjusted by turning it with a screwdriver until there is a steady 1 1/2 inch to 2 inch flame with no yellow in it.

The new thermocouple may be a cheap or a defective one. The small metal tube that sits directly in the flame, with wires that lead back to the gas valve may be having some problems. Get the vent pipe reinstalled. This problem might be due to bad maintenance also. Clean with a brush so that the air flow becomes free.

Your problem is most likely related to corrosion. The new thermocouple is most likely receiving conflicting information due to corrosion on the downstream side. The corrosion is causing a difference in temp which is causing a shut down. Start at the Thermocouple and work backwards keeping in mind the simpliest seemingly insignificant part can cause all your trouble. Its shutting down as a safety feature but none the less a royal pain in the backside.

A couple of things come to mind. First is the angle of the pilot light. Sometimes the pilot light may be bent a little to make the flame more steady. Also check to see that the door is closed to the pilot light chamber and is tight.

If you've had the cover off and on a number of times it can be bent. Is air from the flue blowing back? A flapper can be installed in the flue tube to prevent this. Just sit and watch the entire water heating cycle with the lighting door off. Get down there and actually view what may be happening. Is there a surge of gas pressure when the water heating cycle is through?

Perhaps a check of the gas pressure regulator is in order. Perhaps the pilot light is being blown out when the heating cycle begins. Check the pilot light nozzle for residue which may be clogging it. Honestly, I hate this type of water heater, it is very dangerous because there are several kinds of poisonous gasses involved. please be careful. I personally have an electric water heater, expensive? Yes! Safe? Yes.