My bathroom is 22 feet long with a vanity at each end, the shower is located in the middle. I can get and maintain hot water at each vanity but the shower is only hot for a couple of minutes then turns COLD! Can you explain why this would happen?

Hmmm...

How many gallons does your shower head use per minute? If it is a newer shower head it is probably 2.5 gallons per minute. If it is an older shower head then it could be upwards of 10 or more gallons per minute. You can test the shower head by filling a 5 gallon pail and timing it. Let us know the answer and we'll see what we can think of here.

Otherwise, tell us how old the plumbing is, how old the shower valve is and tell us the manufacturer of the valve. Also, tell me what heats your hot water and what capacity in gallons the tank is and again, we'll see what we can come up with.

Mark