Water Heater Failure

How old is the thermocouple? If original to heater, replace with new.

Ditto.

From past experiences with gas fired hot water heaters, the thermocouple is probably bad. It's a 30 minute job (worst case) and doesn't require breaking into the gas lines so you won't need a plumber to mess with the gas. Basically, it is the device that "proofs" the flame for the pilot light or the main burner if electrically ignited.

Try turning off gas, removing pilot nozzle and blowing it out. Just a little bit of dust or contamination can interfere with gas flow.

Could be control valve also.

I had this problem and it turned out to be a baffle or barrier below the burner, designed to prevent the ignition of flammable fumes or vapors (like gasoline). The combustion air has to pass through this and it needs periodic cleaning.

Thermocouples are cheap and available almost everywhere. Make sure you measure the length of your old one before you head to the hardware store. Even if this doesn't fix you up, you've eliminated it as the source of the problem.

Started my career selling Honeywell Water heater Thermostat.

No problem. Remember when you press the "krnuled knob" and light pilot, you have to hold it down for one-minute before the thermocouple tip gets hot enough to stable the pilot. Why? because the thermocouple is made of 2 dissimilar wire welded together so when they get hot there expand and contract in different direction resulting in millivolt current generated enough the activate the pilot stat (and electrical unit under the knob) to magnetize and stick to the end tip(inside) of the thermocouple. when this happens the gas passes on to the pilot burner and the pilot is stable.

Your problem - (a) The tip of the thermocouple has carbon or has shifted from the direct flame of the pilot. Take a sand paper and clean the tip and ensure that it is directly centered with the flame of the pilot.

or

(b) the hole of the pilot burner has clogged and the flow/flame of gas is not sufficient enough to heat the thermocouple. Open pilot tip and clean with thin wire the orifice.

or

(c) there is a draft from underneath and the pilot extinguishes. Cover to ensure that the air draft does not hamper the pilot burning.

Thanks to all .. I didn't anticipate the slightly guilty feeling I got by tossing out this Question & recieving such great responses. The suggestions are sure to result in happier home (just ask my wife). Thanks to CR4 too.

I'll add another suggestion that's probably obvious and that is to make sure there is sufficient combustion air. Thought I had a hot water heater thermocouple problem a few years ago. Thermocouple was part of the burner assembly. Operated fine in the warm months but when forced air gas furnace (with electronic ignition) started in the fall, pilot in nearby hot water heater would occasionally go out. Problem turned out to be insufficient air to hot water heater pilot.

Several good answers already here to fix the problems, but I would like to say that anything using a pilot flame should be replaced/updated as it just wastes gas.....

Maybe the manufacturer makes a replacement igniter unit to make it a bit more modern......and far less wasteful too!!

Actually it doesn't waste gas, it helps keep the water hot due to storage losses. Of course, in the case of a tank-less heater, electronic ignition makes good sense. Oh, by the way, I do enjoy a hot shower even when the electrical service is down due to storms or what-not. Those with electronic ignition hot water heaters get to enjoy cold water bathing in short order.

I leave the pilot light burning on my gas hot air furnace burning year 'round. Why, you would ask?

The pilot light burning in the furnace keeps the heat exchanger "dry" and prevents corrosion of the heat exchanger due to temperature and humidity changes. It greatly improves the life of the one part that tends to fail first in a furnace. That's something that most people don't think about. The cost of the gas for the pilot light is miniscule compared to new furnace or heat exchanger replacement. Plus I don't have to remember to re-light the pilot at the beginning of the heating season. I can't say exactly when the heating season begins, but if my wife turns up the heat and there isn't any, it gets very cold around the homestead if you know what I mean.

You would not be so lucky here, they were banned years ago!!

As to whether they prevent corrosion........surely the heating element is built of metal that does not corrode easily or is protected in some manner with plating or whatever.........

Also using it at least once a day must dry it out (if it got wet, also unlikely without a leak!).......or do you live in a tropical area with extremely high humidity.....? We have generally around 45% and no such problems...

The electrical problems of the igniter can be easily remedied with a relatively small cheap inverter and a good sized LA Battery......that is if you are often in blackouts......we are lucky, only 2 very short blackouts in almost 25 years - at least in the time we have been at home!

Germany's electrical system appears to be very, very stable & we are very lucky in that respect! (But I do have a small inverter for the Central heating pump and the ignition - just in case!! Only used in a test, never in reality.....)

Our present central heating boiler is about 18 years old and was already fitted with electronic ignition......and I would bet real money that we were nowhere near to being the first here to buy one!!!

I have never seen a new heater of any sort with a pilot flame in the almost 30 years I have been in Germany, I think it was probably about 1976 in the UK that I last saw one..........the last one I actually saw of any age, was our previous central heating and that was installed new sometime in the mid '60s.....

I have tested a trick out for our pellets oven (in the event of a blackout!), so that the inverter can cope with the load, is to unplug the heating tube (250 Watt) and use a fire lighter, works really great as the rest does not take much current when starting/running......and the electronics is not clever enough to know that the tube is unplugged!!!

Also, having a (often forgotten?) nacked flame in a house, could prove dangerous in the event of a gas leak, or even a leaking petrol canister nearby or similar.....

Wow. Where were you Sir Robin? This is the first time I seen you though you have nearly 1000 entries. Me ducon. live in same forest, fight against bad king john.

(semi- final results) Thanks to all for their help. After blowing out the pilot area & replacing the thermocouple (I found a test: pull connection to regulator & it should measures [across copper body & tip center] 12 mv after 60 sec. of pilot heating). The thermostat was OK (closed circuit) too. On one occassion after lighting pilot successfully I tapped on the gas valve control regulator just one time - just lightly & the pilot flame went out.... My wife called WHIRPOOL & their tech support said after repeating these tests that the regulator was defective - under warranty apparently - so now I am waiting on service. Thanks again everyone. Carlos