Need more hot water in shower

[toolman513]

The shower furthest from the water heater has very little hot water coming out. I have replaced the valve in the shower knob but that did not aleviate the problem. I have plenty of hot water around the house except for this shower, what can I do?

[sloooo]

When you turn the hot water on only, does the water come out at about the same rate as the other showers?

[toolman513]

The water remains the same but as you turn it to the hot side the pressure goes down.

[toolman513]

When you turn the hot water on only, does the water come out at about the same rate as the other showers?

No, the rate is less.

[Phelps]

Did this problem suddenly happen?

When you replaced the cartridge, did you notice any rust chunks/sediment (perhaps even plastic from water heater dip tube) inside the cartridge mixer valve hole? If so, you maybe should have flushed the lines first with the cartridge out, with the aid of an assistant, while you possibly rig opening with a tube over it so that water does not go into wall cavity. And with a clean tub first so you can see if any sediment comes out.

What are your water lines made of?: Galvanized? Galvanized with sections here and there of copper that someone has put in? All copper? Pex?

We know that the water is good exiting the water heater based on what you have said. UNLESS...you are being fooled by what appears to be better volume at other fixtures. If in doubt, confirm the flow rate at the various other hot water faucets and compare. Faucet aerators can make it appear you have more volume than you actually do.

[toolman513]

I did not flush the water line as it was behind the shower wall. The pipes are made of copper. I will try to flush the line and check the aerators just to make sure. I thought the water heater might not be providing enough hot water.

[Phelps]

If your last sentence was true, you would not be getting sufficient hot water ANYwhere.

Let us know how you make out.