My water heater gives me hot water for 15 20 seconds and then it become cold.also when I shut off the cold water inlet I still get water from hot wayer faucet.my water heater is absolutely new.I called the company and they say that there is something wrong with mixing valve. Can you please advise

Hi anilj and Welcome to The Plumbing Page. At AskMeHelpDesk.com. You're responding to a 4 year old dead thread so I gave you one of your own. Look in then upper left hand corner of the first post form the date in the first post before you post, Thanks,

Is there a recirculating system installed? If you don't have a recirculating system I'd be giving a hard look at the dip tube, If the installer soldered directly on the cold water inlet he could have melted the plastic lip on the dip tube allowing it to fall into the tank. Good luck, Tom

How old is your water heater, is this a new installed or old one?

In any case I agree with Tom that it could be the dip tube, Thanks.

John

Hey John,
This is a new installation.
I called the company and they say that there is something wrong with mixing valve.
when I shut off the cold water inlet I still get water from hot wayer faucet. This could be a bad mixing valve or a cross connection somewhere.
Try this. Go around to each one handled tap and shut it off at the stops one at a time. Keep the water heater shut off valve closed. Turn on a hot water faucet. As you shut off each one handle valve you'll come to one that stops the flow of water out of the open faucet. That will be your bad faucet. Good luck. Tom

Sorry Tom I missed that portion, Thanks.

John