I have only warm water coming through the hot water taps. I have an anti scalding valve but it open al the way. All taps in the house are all the same temperature.

Do you have an electric or gas water heater? Does the anti scald device serve the whole house hot water, or just the shower?

The valve serves the whole house and it is gas

So should we assume you have a water heater fired by gas or electric? Try draining water from the drain valve, is it much hotter than the taps?

Do as ballengerb1 suggest. Or run hot water in a tap and feel the hot side water line on top of the water heater before it goes into the tempering device. If its nice and hot, but the oulet of the temp device is just warm, it sounds like you need a new tempering device, or at least a rebuild kit, if one is available for your specific device. Im really leaning toward a faulty temp control. Let us know what you find and we should be able to tell you what's what.

Or a new dip tube. A deteriorated tube will give real hot water for about 1 minute before going slightly warm

Yep, I agree Bob. Lets see what Shosein finds.

The water in the hot water tank is hot, very hot. But the tap are just warm water I haven't had a hot shower in awhile it s a gas heated water tank

I thought I should tell you the hot water tank also heats the furnus it is the reasone the mixing valve is for the entire house

Sure sounds like you need a new mixing valve. However, at this point, I think I would call in the company that installed your system, or at least a company that can work on it. What brand is your system? Is it like a lennox complete heat, or just a boiler that also heats the domestic hot water. Can you post some pics?