Copper tube to cold water inlet on Water Heater is Warm/Hot


Here's the story:
I have a 40gal gas water heater that is only 9 months old - it's a Rheem Fury model 22V40F1.
Within the last few weeks it has been performing very poorly. We used to take showers sequentially and never run out... now we run out after the first and during the first the cold water must be turned down every 3 minutes to maintain a constant warm/hot shower. The water from the kitchen faucet used to be scalding (tons of steam rising like crazy) and now it doesn't even break 115 degrees F. I have not changed the setting on the thermostat since the beginning and it has always been set a tick mark or two above the white mark (which according ot Rheem the white mark is at 120.
I had the plumber who installed it come in to take a look but he wasn't very helpful and passively brushed off my comments and concerns. He basically said (after much prodding) it could be the diptube or the check valve but that rarely happens so we wouldn't check them. Well... enough about the plumber or I'd go off-topic.
I ended up calling Rheem to find what I could do and they gave me a test that I was/am planning to take: 28 gallons of hot water should come out within 10 degrees of the thermostat setting. Well, I went down to the water heater to look it over just to get an idea of what I needed to do for this test. While looking it over I noticed that the copper tube that goes to the cold inlet of the water heater was warm/ hot (I'd say at around 105 degrees F). Any reason this should be?
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normally both inlet and output lines will be hot. the hottest water is in the top of the tank and both lines live in the top of the tank so both will be about the same temp, except inlet line will be cooler during peak demand times
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With a standard shower head flow rate of 2 GPM ,that gives you 14 minutes of shower.

Is it supposed to stick down into the heated water? Then conduction would explain the warmth.Does it cool off when water is being pulled from the tank?
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Jim Yanik
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Thanks, that would explain it then!

Gas
That would be 14 minutes of a hot shower without having to turn down the cold, correct?

I'm sure it's because of the conduction; I haven't tested that yet and may or may not; thanks though.
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wrote:

Imho, sounds like conduction. Because of this heat loss, it's recommended to also insulate the cold water line within 10 feet of the hw.
tom @ www.FreelancingProjects.com
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