Water heater or plumbing issue

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Water heater or plumbing issue

Author: dypjj28 (CA)

I got a new GAS water heater 40 gallons last July due to the 15 years old one went dead. Everything worked fine for 4 months until November. Suddenly my ENTIRE house has hot water lasting for 5 to 7 minutes and then turns luke warm. Again, it's the whole house. Water heater installed checked dip tube, replaced thermostat and tried to get buckets of water out. It all looks fine. The only thing is the last few buckets of water gets cooler like 15% cooler. I turned the thermostat to level C, next to the hottest, and does the same thing.

Next, plumber helped me do a test, shutting all hot water from the tank, and turned on every single faucet to the hottest. There were couple bath faucets dripping cold water. So they concluded to replace both faucet mix control valves. They did both, and one is still dripping cold water after we disconnected all hot water supply. I am so crazy about this now not sure it's a plumbing issue or water heater issue (as installer tries to avoid replacing it if it's a plumbing issue)

Also, the only thing I can remember is my furnace/heating guy crawl in my house crawl space and not sure he hit something to trigger the wrong cold water mix?? The reason I think this way is because the problem starter right after that day.....any thoughts will be GREATLY APPRECIATED, as I need to take a quick shower which is manageable but not my 85 years old mom....Thanks thanks thanks!!!

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Re: Water heater or plumbing issue
Author: steve (CA) Feel the water heater outlet pipe when hot water is first being used and then feel again when warm water is coming out of the faucet/shower. See if there's a difference. See if the burner is coming on when water is only warm. With the control set at C, it should be VERY hot coming out of the faucets(maybe 150*).
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Re: Water heater or plumbing issue
Author: dypjj28 (CA) Yes there is difference, it matches the cool down at the faucet, it's from pretty hot to warm hot. Does this mean it's water heater problem since it is directly from the heater? Thx
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Re: Water heater or plumbing issue
Author: steve (CA) If the water exiting the heater that soon turns warm and the burner isn't on, there's a problem with the heater.
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Re: Water heater or plumbing issue
Author: dypjj28 (CA) Thanks, let me start from this direction. Will post once problem identified...
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