gas hot water heater, pilot light will not stay lit and now will not light, i have natural gas?

Question

have natural gas so i know i am not out of gas

Answer 1

There's some part on it (thermocouple) that went bad, had the same thing happen to me You may have to call for help. The good news is that it's a pretty minor part, so it shouldn't cost much.

Answer 2

I know this problem occurred more than 3 years ago now but it will be a recurring problem for many years to come across the world. Thermocouples used to detect that the gas pilot is alight in hot water heaters and furnaces are not just any old thermocouples, the thermocouple needs to have a very low circuit resistance of about .03-.05 ohms and that's why the internal conductor is such a large gauge (2 mm or more in diameter) and also why the main length of the inner conductor and out conductor are copper. The dissimilar metal that makes up a thermocouple is restricted to only the very end tip in the flame for thermocouples intended for this type of service (gas pilot) and these thermocouples are usually type T (Copper Constantan) which have a typical temperature coefficient of around 40uV/degrees Celsius. It is not sufficient to just measure the voltage with a high impedance voltmeter, the thermocouple must be able to deliver over 1 ampere to 1.5 amperes in the normal circuit. The electromagnet used in gas controls consists of perhaps only 30 turns of heavy gauge wire wound on a high permeability horseshoe shaped core and the hold in current to keep the gas valve ON is usually about 1 ampere! Any oxidation of the soft soldered contact on the end of the thermocouple or the development of a slightly higher resistance joint at the flame end of the thermocouple which is in the flame will result in the failure to operate. In your case because both the controller and the thermocouple were swapped out it will the hard to know but it is almost certainly the thermocouple that was the problem for the above reasons. I hope this helps someone else as this problem will always re-occur as the circuit resistance for normal operation has to be so low, it is easily upset with the slightest change. Better made thermocouples have the constantan wire welded inside the tip but another technique is to simply crimp the centre constantan wire to the tip and these will eventually fail with thermal cycling, failure meaning that the circuit resistance rises above 0.05 ohms.

Answer 3

If the pilot will not light at all, either tha gas supply has been interrupted (you did pay your bill?) or the gas valve has failed. The usual failure mode is not of the gas valve itself -- it is of the thermocouple, the cylindrical gadget that the pilot flame impinges on, and which is connected to the gas valve by a thin copper tube: these die from time to time, and can be easily and cheaply replaced. But if you can get no flame at all, that is not your problem. Replacing a gas valve is not particularly difficult, although it generally involved draining the tank.

Answer 4

Replacing the gas control valve is probably what needs to be done here. There's a one time thermal fuse on the back of the valve that, when blown, usually because of an overheated situation, won't come back on to allow gas to flow anymore, even when the red button is held down. The valve itself is usually quite expensive and as the previous answerer said, involves draining the tank first. The valve itself just unscrews out of the side of the tank and the new one screws back in, of course, but if your unit is over 5 years old, it may be more economical for you to just replace the whole thing. If you do go for replacing the valve, the biggest pipe coming out of the bottom is the main gas line to the burner and is usually a left handed thread.

Answer 5

Your thermocouple (senses heat from pilot light)is probably shot. It should create a small voltage when the pilot light is lit, which then allows the main gas valve to open.

Unless you are fairly experienced with gas valves and gas heaters, I suggest you hire a professional to replace it. Your gas company will be happy to recommend a contractor.

Answer 6

If it would not stay lit then that would be either a dirty pilot or the Thermocouple was bad. But now you say it will not lite at all? That could be a blocked pilot orifice which could be why it wasn't staying lit in the first place.

Answer 7

There usually is a little thinghy which checks whether the flame is actually on, to avoid gas streaming out when the flame is off. This thinghy if broken will result in a broken flame. Get a specialist in to fix it.

Answer 8

do you have an emergency shut off valve? like an earthquake valve? make sure that hasn't been tripped since those will cut off your supply and they you won't be able to relight the pilot. its happened to my parents a few times. You can also call your gas company and they can send someone out to look at your equipment.

Answer 9

you need to prime the line. hold in the pilot light button and light. Now you must continue to hold in the button for about 2 minutes. If you release it to soon, the pilot will go out.

Answer 10

Call the service guy. It could be a thermo switch. These go quite a bit. Had to replace two for furnaces over the last 7 years.