Hi,
This is my first time here and found a wealth of knowledge which made me register and post this.

I had a RHEEM 50 gallon Gas water heater for about 10 years. Our faucets (sinks and bath tubs) have a single control for hot and cold water. Turn clockwise more and more to get hot water and anti-clockwise for cold water. Lately we saw less and less hot water coming in or we have to turn the faucets way to the max to get enough hot water to last a shower. I thought that the water heater was on its last leg and it might be time to replace it instead of calling someone to open it and see what is wrong (maybe a mistake). Anyway, now I have a brand new Whirlpool Gas Water heater installed, but have the same issue.

This makes me believe that it is the pipes and not the water heater. Where do I begin? I read about using vinegar to let it clean the sediment from the pipes, some way to backflush the pipes or even checking the dip tube. I am handy, but probably not handy enough to risk a lot of plumbing work.

What I also found that the cold and hot water pipes coming out of the Water heater are both hot. Should they both be hot? I would expect the cold water pipe to be sending cold water into the heater and would be cold.

Any thoughts?

Thank you !!