Wehave a new two stage hot water heater electric. We have to turn on two sources to get hot water. As soon as you turn off one faucet, the water gets cooler in the other. We have a big jaccuzzi tub, hard to get enough hot water in it without also running the shower. Never had a two stage before... whats up?

Who installed the water heater? Tankless water heaters require a certain amount of flow to operate correctly. What brand heater is it? Make and model.

It's not tankless, 50 gallon two stage e1f50rd045v, Whirlpool, plumbers installed, just prior to closing on house

Is there a recirc pump on the system. May be best to have the installer back to see what's happening. This sounds strange indeed. Hope one of the others here can shed some lite on your situation. Im not familiar with your water heater, sorry I couldn't help. Please let us know what you find.

Nothing

Cold baths