Hello everyone.
Here is my problem.
I installed a new water heater in my house around Christmas 2015. After that I had only 1 or 2 warm showers and now I'm lucky if I can get it luke warm. I called bath fitter and had them replace the thermostatic mixing valve that was still covered under warranty. That did not fix the problem. I then went downstairs with the technician to check the pipes around the water heater. Some were hot some were warm and some were cold. Do my dad and I took apart the pipes last night and cleaned out all the lines and reassembled everything. No change in temprature. We then went to the shower and disassembled all the valve workings and reassembled. Now we have less pressure and less than Luke warm water.
My father is a maintenance man for 40+ years and he is stumped. Bath fitter says its out of their hands now and there is nothing more they can do.
Can someone please help with this problem?
I can post more information if needed.

Nothing you have posted gives us any clue as to the cause of the problem, but I wonder what you mean when you say you "cleaned out the pipes" because that sounds like a lot of work that was unnecessary, at least until you found out WHAT was causing the problem.

Gas? Electric?

It's electric. And when I saycleaned out, I mean we cut the pipe on the spot where it went from warm to cold and took a coat hanger and stuck down in the pipe to clean out debris. Last summer there was some work done on water lines on my street leading to a lot of dirt and junk in the pipes. Also, we thought there may have been a calcium build up blocking the flow of warm water. We took off 1 elbow and cleaned on both sides of 2 T- style connections. The shower is directly above the water heater so to give a more accurate picture I will describe the piping. A hot water line comes out of the heater, goes up 3 feet and makes a bend to the left. Then after about 2 feet it has a T where it goes one direction to the bathroom and the other direction to the basement sink and kitchen. We cleaned that T and cut on the shower side of it and cleaned all the pipe between there and the shower. The. Replaced the T and elbows. We removed a little calcium buildup, but I'm still unsure why we have less pressure now.

When you hooked up the new heater, you filled it before you turned breaker on correct? Ususally with most DIY'ers this is the most common mistake with electric water heaters. Have you checked the current at the elements? Thermostat tripping?

The breaker was off before filling and elements are good.

What brand and model of electric water heater did you purchase? Was the box taped shut, glued or stapled. Your water heater is still covered by a warranty. Consider returning it for a new one.

Best Wishes