This product was recommended by the plumber who installed our new water tank in our oil burner furnace 3 years ago. We use an all-house water filter, and we followed his advice for the furnace in light of what happened to the old water tank and the anode rods. We change the AP431 filter every 6 months. So far, so good. Happy with the product. It’s easy to remove the old one and install the new one.