When I open the tap get cold water after 5 minute get the hot water. I asked the water tank rental company they came and said problem with shut off valve not with the tank. Can someone let me know problem with water tank for shut of valve.

Your situation is unclear. When you open the hot tap is the water cold for 5 minutes then gets hot... or... when you open the cold tap is the water cold for 5 minutes then gets hot? Did this problem just start? Has there been any other work done to the plumbing recently? You may need to call a plumber if details aren't available.

When I open the hot water tap for 5 minutes get cold water the after 5 minutes get the hot water. That too sometime goes back to cold water.

Does this happen through the whole house or at only one faucet. If it is happening through the whole house you may have a rotted and broken dip tube inside the hot water tank especially if this problem just started recently. The hot water tank also may not be heating properly. I don't see how a shut off valve could cause this problem but I'm not there to do diagnostics on site.

When I open the hot tap the water is cold for 5 minutes then gets hot, when I open the cold water its always cold water. No pluming was done recently this started of the bloom. Then I thought the problem with water tamk and called the water tank company and they say no problem with tank problem with shut off valve. Want to make before calling the plumber this is shut off valve issue or tank problem.

When I open the hot tap the water is cold for 5 minutes then gets hot, when I open the cold water its always cold water. No pluming was done recently this started of the bloom. Then I thought the problem with water tamk and called the water tank company and they say no problem with tank problem with shut off valve. Want to make before calling the plumber this is shut off valve issue or tank problem.

Thanks for the comments

This happen to whole house at least it takes 5 minutes for hot water come to the tap until we close the tap. Once again when we open the tap after half an hour the problem repates again.