Just built a brand new house. The problem I dont understand is that we are experiencing reduced water pressure when we operate two fixtures simultaneously. For instance, turn on sink, hot or cold water then flush toilet and flow from faucet is cut in half. When toilet is full and shuts off faucet flow is restored to normal. Same thing happens with toilet and shower or sink and dishwasher. Happens with any combination of water too, such as cold and cold or hot and cold. We do have a tankless water heater and a well. Although at our other house we had a well and a conventional hot water heater and did not have this problem. Could the tankless heater be the issue or is it something else?
cold doesn't flow through the water heater, so if the pressure drop is the same regardless of the combination, it's not the water heater. i would imagine it has something to do with the well or how the water is pumped from the well and possibly can't keep the water pressure up at a certain flow rate.