I installed a tankless hot water heater. It does supply endless hot water. But the pressure is diminished quite a bit I figure it's because I live in a 3 story semi. I went back to the regular hot water heater and kept my tankless also. The pressure is great now. My question is can I direct the tankless hot water directly into the regular HWH instead of cold water feeding into it So it does not have to heat the water as much and possibly cut down some of the gas expense.

Your pressure is likely unchanged but you are seeing a decrees in volume. Tankless heaters frequently throttle the volume to allow time for the heater to work. Sorry you already made this switch back. I would have lower the setting on the tankless which would have boosted the volume a bit. By connecting both types of heater you are not going to save on gas, I think you have created a system that will do the opposite

Thank you. Now that I am stuck with both units, I believe it would do no harm by sending the hot water from the tankless unit into the regular hot water tank so it works less. Am I correct?

Thank you. Now that i am stuck with both units, I believe it would do no harm by sending the hot water from the tankless unit into the regular hot water tank so it works less. am I correct?

I can see no problem in hooking the two heaters in series. It makes a lot less work for the regular water heater. Good luck, Tom

Thank you Tom you confirmed my believe.

You're welcome. Let us know if we can help in the future, Good luck, Tom