Okay, Im sure Im not gonna know all the sufficient info needed to get the best advice but I will try to be as descriptive as possible. I live in a newer concrete block construction house with 21/2 baths- master bath has large garden tub with typical moen faucet- hot on left cold on right and showers have fancier single lever with glass circlular backing- up is on and right is hot and cold is left dual unit shower. Guest bath has delta turn lever with 12 o clock is mix of hot and cold and 3 o clock is off and 9 o clock is all hot. Kitchen is moen with single lever- up is on and up and over right is cold, left is hot. Water heater (i think) is tankless eco smart with temp set at 140. PROBLEM: sporadic temps - kitchen sink- works great- super hot and consistent. Guest bath- water goes from hot to cold. Master bath- tub with only hot water side turned on only gets slightly hot for a few seconds then goes to luke warm- even cold. Master bath showers get somewhat hot when turned to all hot and is not consistent nor hot enough for my liking- not even close to temp water is in kitchen. The guest bath is only a few feet in distance to kitchen sink and all the fixtures are different leading me to believe its not likely the fixture itself or the heater since its doing great for the kitchen- WHAT COULD THIS BE??? Thanks!!