On Demand electric water heater on a well, works intermittently. Replaced 3 X over 12 years, the problem persists and I'm sick of it. My gut says it's about water pressure/flow, because sometimes you can trick it into working by turning on the sink tap and the shower at the same time. Sometimes that doesn't work either.
The current unit is EcoSmart ECO 11. This services a shower and bathroom sink. Ideas I'm considering- a bigger bladder tank to increase pressure coming in, adding some kind of in-line reducer to increase pressure, adding a mini-tank heater inline after the on-demand. We can't move up in size on the on-demand, as the wiring isn't there to move up. Ideas?