Gas water heater inop this morning, fix cost nothing.

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Old 05-14-19, 12:38 PM
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Gas water heater inop this morning, fix cost nothing.

This water heater was installed new in 2004 and worked flawlessly until this morning when I got no hot water. I never worked on a water heater so looked up the manual online. Looks like the pilot light was out and that the thermocouple might be bad. Said to remove the burner unit as step 1. Got it out and it was obvious what the problem was. Burner was covered in a thick layer of rust flakes. Surprised it worked at all before. Anyway, I dumped out the rust and put it back together. Got it started again just fine. Repair cost, zero. Just wonder how long it will take to heat up again.

 
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Old 05-14-19, 01:06 PM
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As I recall a 40 gallon tank will take about 30 minutes to heat up. The nameplate might give the recovery rate.

One BTU is the amount of heat energy required to raise one pound of water by 1F. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1F.

A common input is 34,000 BTUs on a 40-gallon tank and 36,000 BTUs on a 50-gallon tank. The higher the BTU input and efficiency, the faster the recovery.

Temperature setting (110?, 120?) minus incoming water temp (50?) is the number of degrees you need to heat.

For illustration purpose say 50 degrees.

50 X 8.33 BTU X 40 gal. = 16,660 BTU.

If 34,000 BTU input: 16660/34000 = .49 hours = 29.4 minutes.

Eat a sandwich then take your shower.
 
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Old 05-14-19, 01:54 PM
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Well, I spoke too soon. Stopped working again. Tested the thermocouple according to the manual and it's not putting out any voltage. Off to Home Depot.
 
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Old 05-14-19, 06:13 PM
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Its not the thermocouple. And dont put a regular one in there..

That couple has a thermistor on it. When the chamber overheats it will trip. The chamber is overheating because the cordierite disk is clogged. The burner is starving for air.

If you change the t couple to a none OEM one you by pass a important safety device. You can DIE!!!!! CO poison from lack of draft.. ETC ETC..

2004, replace the heater. They were a bad design from AO smith . Those series 100's were short lived...

Whats you and your family's life worth????
 
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Old 05-14-19, 06:21 PM
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You're right, not the thermocouple per say but the thermistor is bad. Soldered in a temporary bypass until I get a new pilot assembly.
 
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Old 05-15-19, 04:12 PM
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Thermistor probably not bad. They are resettable when they cool..

Since you bypassed a safety device I will close this thread.

Any ao smith rep carries these on the truck. Call in a pro. Replace the heater!!!!!

You put you and your family's life in jeopardy..

Even after you change that part you will have the same issue. Its the air intake on the heater thats the issue. I will not repeat myself.

You can DIE!!!!

Without you even telling me the water heater make I know its an AO smith or state select series 100 water heater.. Ive been doing this 30 plus years pal... trust me..
 
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