ODER FROM WATER HEATER HOT WATER ONLY - Water Water Heaters

Anode rod will react with harmless bacteria and cause odor in hot water
Troubleshoot and replacement steps following link:
http://waterheatertimer.org/Replace-anode-rod.html

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Usually it has to do with the water supply, if the source is a well, have the water tested. Your local Health Department can direct you to testing companies. I just had my well re-tested, a good series of tests will cost about $100.00.

You didn't say if it's natural or propane gas but it sounds like a gas leak. You should have it checked.

Did you put hot to hot side? And cold to cold side?
Cold water pipe usually has shut-off valve.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#new

Add comment and say brand and type of water heater for possible follow-up

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

tank water heater? if so its because the water is much colder this time of year. water heater has to work harder to heat 40deg. water than 70deg. water in the summer. That also means as you use the hot water from the tank its replaced with very cold water. Causing you to have less hot water. Either get a larger water heater. Or even better go tankless and have never ending hot water and save money at the same time.

Generally tank odors are bacteria reacting with anode rod.
Make sure odor is isolated to water heater, and on hot water line only so you know water heater is best suspect.
Change anode rod.
http://waterheatertimer.org/Replace-anode-rod.html

Your plumber will know all about anode rods and will have tools or impact wrench for removing old anode rod.

Hello STOP!!!!! don't push the reset button any more.You have a ignition/spark problem.You will load the chamber with oil and will cause major problems when it lites off.Replace the ignition TRANSFORMER on the burner.Avalible for (beckett burner) at home depot/lowes.

3 minutes?? does the water run cold then? or just warm?
Is this what the tank you replaced was doing? If so, then you may have: 1 a recirculating pump instant hot water system thats faulty and allowing cold water backflow into hot water piping. 2 A tempering valve that has stuck, allowing cold water into your hot water system.
Or maybe a broken or missing dip tube in your new heater.
If after 3 minutes the water is coming cold out leave that faucet running and go to heater and feel the hot water outlet pipe from the heater. if that pipe is hot then the heater is not the problem. If the hot pipe from the heater is cold the heater is the problem. (Make sure the cold pipe coming into the heater is connected to the Right side marked "cold" !) If there is a tempering valve by the heater: feel the output from the tempering valve, if it is cold and the pipe from the heater to the tempering valve is hot, then the tempering valve is the problem. If all these are OK somewhere in your plumbing system hot and cold may be connected possibly a faucet or showerhead that is shut off at the spout/head, but hot/cold handles are left turned on then cold water can backflow thru hot pipe.

wants flushing through refilled and bleed

try flushing out the hot water heater, they usually get build up in them which can cause smell. if not look for what they call a charcoal filter and install it after the water heater or any filter that will filter oder and taste. 3m makes a nice one and so does CUNO