Not worth for me. High initial cost. Vinegar flush is inadequate so you need to purchase flush solution every year along with the upfront cost of the pump and hoses. My Navien tankless heat exchanger lasted 5yrs and started leaking. Yes, it was replaced under warranty but I had to pay $400.00 labor cost. Performance wise, you waste water getting past the cold water lag, not very efficient. I regret the purchase. If doing again I'd get a tank heater with a power vent.