Electric water heater problems

I am having problems with my waterheater decreasing the amount of water as I take a shower, meaning the longer the shower is the less hot water I have. Talking to some people I thought it was one of the elements, I tested both meters with the power off and one wire disconnected and they both read infinite to the mounting bolts and around 15 ohms across the terminals. Do these readings sound right, the stuff I read on the web said it should read what I meausred. Any other suggestions the only things I can think of is the thermostats, or there is allot of crud in tank. Is it a good idea to drain the water heater and refill it to get rid of any build up? Also everything I read said to test the thermostats but I can't find any instructions on the procedure to test these. The model is a Richmond Miser model #8V5-2C 220V 50 gallon. Thanks for your help

Don't make yourself nuts with this. Most of the guys in the field cut to the chase on water heater problems. Just yank the elements (make sure you replace with the right sized element) and yank the thermostats and replace it all.

And yes, you should drain the tank regularly. When I drain a tank, once it quits draining, I like to hit the cold a few times to stir up any remaining buildup in the tank. You should service the tank at least yearly. But I know some plumbers who insist on servicing the tank every three months.

If the unit is older than 9 years old, you should go ahead and replace the entire unit. I've seen them last a lot longer. But we use 9-years as a good rule of thumb in the field. I had an old unit in one of my rental houses that was 40-years old.

good luck with it.