Lack of very hot water to some parts of house

[tsstriangle]

Hi there, first time poster here. Would appreciate any and all advice. I'm having a strange issue with our hot water. We have three full bathrooms. All bathrooms share the same lines as the two are next to each and the 3rd is directly on the floor below.

The master bath sinks get pretty good hot water, the master shower gets very hot....but not always. Sometimes it's less hot than others

The second bath only gets lukewarm, same with the faucets.

The third bath is a little warmer, same with the faucets.

The actual water flow out of the hot lines are fine.

The two suspects are failing water heater, or deposits in the water line. But I can't see how either of those are the issue because water IS flowing through the hot line...it's just not very hot in some areas. And that brings us to the water heater, which I imagine it wouldn't be hot in the master shower if it wasn't working. Water heater is gas. Help!

 

[Mr_David]

Tough to evaluate from here. Common problem is a single handle fixture like a tub/shower valve. water maybe flowing through the fixture even when it is turned off.

if you have good ball valve on the cold supply to the water heater and any 2 handle faucets in the house, try this

Turn off water to water heater. open hot side of a 2 handle faucet. water should stop flowing from faucet from faucet.
If not you have water crossing over somewhere in your system.
put your ear to the other fixture and see if you hear the water passing through them