u/BudWilly

My condo has an on-demand water heater. When I take a shower, it takes about 3 minutes for the water to heat up. My kitchen sink is a different story. Lately, no matter how long I let the water run, it never gets hot. I figured out that if I "prime" my hot water by turning on my shower first, then the water at my sink gets hot. My condo is on the second floor and the heater is on the outside wall about 5 feet from ground level. I'm guessing the heater is about 10 years old. Do I need to replace? Thank you!