Natural Gas fired Water Heater no and low heat issue

[Diesel911]

Note that the Pilot Light was always on but the Water was lukewarm. I really had to drain off a lot or out of the Tank to get the temp low enough to start the main burner. After which even on the hottest temp setting the Water would heat up to lukewarm and then the Burner would not come on again.

Meaning that that at daytime temps the Burner was never going to go on.

I am well used to the non-functioning Thermocouple being the source of the no heat issue but when that happens you cannot keep the Pilot Light on. But, that did not fit the symptoms I was having as the Pilot Light would remain on.

But, the Internet provided a clue.
http://answers.angieslist.com/The-pilot-light-water-heater-lit-burner-light-q132803.aspx

In the text of the sit it casually mentioned that the Thermocouple can keep the Burner from going on even though the Pilot Light is on (I did not know that was possiable). The other cause was if the Thermostat on the Gas Controller was not working right.

I salvaged another Gas Controller from My Mothers Old Water Heater I changed out last Year also thinking I could salvage the Thermocouple. But, no luck there the thermocouple had a chip out of the tip of it.

I really thought the Gas Controller was the problem but the Gas Controller on My own Water Heater was going to be hard to get off so I opted to by a new Thermocouple. It turned out the thermocouple was only $11.26 each.

In short to my surprise installing the new Thermocouple worked and the Water Heater has been working for 2 Days now.

Another thing I learned from the Internet site is if you do not get a Pilot Light when you press down and hold the Star Button the Orifice in the Pilot Light Pilot Tube could be plugged.

This happened a long time ago (1970s) but I found the Gas was not coming out to the Burner and the Pilot Light and there was Gas pressure at the Gas Controller Inlet. I left the Gas Controller on the Water Heater but took it apart. I found some stinky gummy build up plugging off one of the holes inside. After cleaning the Heater worked fine.

The above are solutions that the Plumbers make some big bucks off of.

[Diesel911]

I forgot to ad make sure the Anode in the Tank is not badly eaten away as my Water Heater is dated 1991. If I had not kept the Anode in good condition the Tank would have been eaten through long ago.