Jack72, you have the same problem I had. My wife wants to take, in her words a 15 minute shower, which is in reality a 45 minute shower. I had already installed a large side arm which gave me a lot of very hot water, but after a time it would get cool. I purchased a 20 plate with 1 inch lines and put it in the cold water line before the water tank and so far, no mater how hard she tries, the one we call crazy, is unable to run me out of hot water. The plate heater is also the last before my pex goes back to the boiler. Sometimes I feel like I over do projects like digging a 4 ft trench for insulated line and pouring a 10 x 20 slab for boiler, and would love to hear about others overdoing, might make me feel a little normal. Hope you never run out of hot water again!